FINAL REPORT 
STUDIES OF FRESHWATER INFLOW EFFECTS ON THE 
LAVACA RIVER DELTA AND LAVACA BAY, TEXAS 
To 
Texas Water Development Board 
P.O. Box 13087 Capitol Station 
Austin, Texas 78711 

DECEMBER 1986 THE UNIVERSITY OF TEXAS AT AUSTIN MARINE SCIENCE INSTITUTE PORT ARANSAS, TEXAS 
78373 
TECHNICAL REPORT NO. TR/86-006 
FINAL REPORT 
STUDIES OF FRESHWATER INFLOW EFFECTS ON THE LAVACA RIVER DELTA 
AND LAVACA BAY, TEXAS 
by 
R.S. Jones, Principal Investigator 
JJ. Cullen & R.G. Lane, Nutrient Dynamics and Primary Producers 
W. Yoon and R.A. Rosson, Nutrient Regeneration 

R.D. Kalke, Zooplankton and Benthos, Project Coordinator 
S.A. Holt & C.R. Arnold, Quantification of Finfish and Shellfish 
P.L. Parker, W.M. Pulich & R.S. Scalan, Stable Isotope Studies 
from 
The University of Texas at Austin 
Marine Science Institute 
Port Aransas, Texas 78373-1267 

to 
Texas Water Development Board 
P.O. Box 13087 Capitol Station 
Austin, Texas 78711 

Contract No. lAC (86-87) 0757 
TWDB Contract # 55-61011 

DECEMBER 1986 
The University of Texas Marine Science Institute 
Technical Report No. TR/86-006 

TABLE OF CONTENTS 
EXECUTIVE SUMMARY Compiled by J.J. Cullen & R.S. Jones iii 
CHAPTER I. INTRODUCTION By R.D. Kalke 1.1 
CHAPTER 2. NUTRIENTS, HYDROGRAPHIC PARAMETERS & PHYTOPLANKTON By J.J. Cullen & R.G. Lane 2.1 
CHAPTER 3. BENTHIC RESPIRATION RATE AND AMMONIUM FLUX By W. Yoon & R.A. Rosson 3.1 
CHAPTER 4. ZOOPLANKTON By R.D. Kalke 4.1 
CHAPTER 5. BENTHOS By R.D. Kalke 5.1 
CHAPTER 6. FINFISH AND SHELLFISH By S.A. Holt & C.R. Arnold 6.1 
CHAPTER 7. STABLE ISOTOPE STUDIES 
7.1
By P.L. Parker, W.M. Pulich & R.S. Scalan 
EXECUTIVE SUMMARY 
Board is concerned with
The Texas Water Development (TWDB) 
management of surface freshwater resources. They must plan on water use by 
urban populations, industry, and agriculture. In addition they must also 
consider the needs of Texas bays and estuaries that have evolved to receive 
freshwater input. In order to better understand these needs, the TWDB has 
been conducting and sponsoring research on the freshwater requirements of 
bays and estuaries in both impounded and non-impounded drainage basins. 
The TWDB contracted with the University of Texas at Austin’s Marine 
Science Institute (UTMSI) for one such project. Officials from TWDB and 
UTMSI met and worked out the components of a two year, multidisciplinary 
in
study on selected sites the upper Lavaca-Tres Palacios Estuary and parts of 
Matagorda Bay. Data were collected on 14 sampling trips between November 
1984 and August 1986. The primary goals were to obtain an environmental 
assessment of the upper Lavaca Bay after completion of the Palmetto Bend 
reservoir project on the Navidad River (dam closed in 1980, forming Lake 
Texana); and to document the use of the lower river delta as a nursery area 
for finfish and shellfish. The study had several components that are reported 
as separate chapters within this report. 
The broad objective of this and similar studies is addressed by three 
questions. What happens when freshwater is introduced into the estuary? 
What happens when freshwater is withheld from the estuary? How much 
freshwater must be introduced to forestall the negative effects of withholding 
it? These questions have little meaning unless there is a clear understanding 
of what processes are being studied and what temporal and spatial scales are 
being considered. There is a crucial relationship between the scales of 
physical forcing and biological response that is dependent on the generation 
times and mobilities of the organisms in question (Haury et al. 1979; Lewis and 
Platt 1982). Because the diverse biological components of an estuarine 
ecosystem have vastly different lifespans and capacity for movement, the 
answers to the three questions above would depend in large part on ecological 
perspective. 
A reasonable approach would be to look at the scale of a
temporal year 
and the spatial scale encompassing the drainage basin. Appropriate biological 
components for study would include larger organisms that integrate their 
environment and may have some economic importance: finfish, shrimp, and 
benthic macrofauna. Unfortunately, many of the effects of physical forcing 
(i.e. freshwater input) on higher trophic levels are likely to be indirectly 
expressed through influences on the productivity and taxonomic composition of 
food resources. So, to answer our three questions in the appropriate context 
for management (relatively long term, large scale, higher trophic levels), it is 
necessary to answer the same questions for lower trophic levels on appropriate 
scales for each biological component. In addition, the nature of biological 
coupling between producers and consumers must be determined. For example, 
what is the relationship between primary production and fish production? The 
problem assumes immense proportions. 
Ideally, a study of the freshwater requirements of an estuary would look 
at statistical relationships between state variables (e.g. salinity, chlorophyll, 
zooplankton abundance, fisheries yield) and also the dynamic processes linking 
the variables (e.g. light-limitation of primary production, feeding habits of 
juvenile fish, etc.). This two-year study with approximately bimonthly 
sampling was by necessity constrained. Systematic sampling provided good 
records of a large number of variables over limited temporal and spatial scales 
but process-oriented studies were beyond the scope of the contract. Many 
addressed in
process-oriented questions are now being a project recently 
initiated in San Antonio Bay. 
Individual are summarized below. A assessment
components general 
completes this summary. 
Nutrients. Hydrographic Parameters and Phytoplankton: 
This component of the study was designed to observe spatial and temporal 
patterns of nutrients and phytoplankton in the Lavaca Bay estuary and to 
interpret the observations with respect to the influence of freshwater input on 
primary production. Strong patterns were found, and these were often related 
to the influence of freshwater. Sampling was inadequate to examine properly 
some relationships such as interannual correlations of nutrients and salinity. 
Also, the statistical relationships that are documented cannot be interpreted as 
demonstrations of causality. 
Year 1 (1984-1985) was relatively wet and Year 2 (1985-1986) was 
relatively dry. A salinity gradient, associated with proximity to freshwater 
concentration
input, was evident throughout the study period. Nitrate seemed 
to reflect the importance of freshwater input nutrient dynamics. High
to 
concentrations were associated with low salinities and concentrations were 
very 
low in the dry year. Nitrite and phosphate were also substantially higher in 
the wet year. Pigment concentrations • were significantly higher in the first 
year, consistent with, but not demonstrating higher primary production. Total 
phosphorus was also higher in fresh water. Total Kjeldahl nitrogen (TKN) 
concentrations were higher in the dry second year. Nitrate and nitrite are not 
measured by the Kjeldahl method. Total nitrogen, here defined as TKN + 
nitrate + nitrite, was not significantly different between years. 
indeed influenced
It is concluded that the Lavaca Bay estuary was by 
freshwater. High nutrient concentrations were associated with freshwater 
input and biological utilization of the nutrients was indicated by nutrient 
depletion away from the input and in the dry year as compared to the wet 
The flushing action of freshwater inflow was evident during sampling
year. 
periods when nutrients were high and chlorophyll was relatively low in low-
salinity water. During other sampling periods, chlorophyll was high in the 
freshwater upstream, apparently as a result of biological utilization of nutrient 
input associated with freshwater. These results are consistent with the notion 
that as flow subsides, nutrients are utilized and phototrophic biomass increases 
in the fresher water. Thus, there is no reason to expect stable relationships 
between salinity, nutrients, and phytoplankton in an estuarine system subject 
to episodic perturbations, at least on the time scale of those perturbations. 
Over months or years, though, freshwater input, nutrients and primary 
production are likely to be related. The differences between a wet year and a 
dry year at Lavaca Bay are consistent with the proposition that freshwater 
input has a strong influence on primary production. The relationship has by 
no means been however.
proven, 
Enhanced flushing associated with freshwater input increases turbidity due 
to sediment resuspension and transport. A model of photosynthesis suggests 
that under a wide range of conditions in Lavaca Bay, increased turbidity is 
to reduce
likely water-column photosynthesis (normalized to chlorophyll). 
Nutrients associated with the same freshwater input should stimulate 
thus
of It
productivity by supporting net growth phytoplankton. is possible 
for primary productivity to be sensitive to both light and nutrients. 
the Lavaca
The importance of very small phytoplankton in Bay estuary 
was demonstrated. Because epifluorescence microscopy was not employed in 
in Texas the
this study and previous studies of bays, phytoplankton 
assemblages have not been fully described. Cell counts and biovolume 
estimates from this study are considered to be relatively poor indicators of 
phytoplankton biomass. The counts do contain substantial amounts of 
information on the relative abundance of identifiable taxa and do show that 
small forms, especially cyanobacteria, were quite abundant. 
Freshwater introduced to a rather salty bay system formed a lens over 
the river in June 1986, restricting vertical mixing and promoting anoxia below 
the surface at two river stations. This phenomenon should be considered when 
assessing the impact of intermittent freshwater input to a high-salinity estuary. 
that
Experience with sampling variability suggested wind-induced mixing 
and sediment resuspension can have pronounced influence on observations. For 
made
example, measurements of pigments on successive days (windy vs calm) at 
the upper bay station varied by a factor of nearly 10, presumably due to 
suspension of microphytobenthos. The biomass of microphytobenthos was found 
to be substantial and distributed well below the millimeter of sediment
upper 
where The the 5
net photosynthesis is possible. amount of pigment in upper 
mm of sediment is on the same order as that in the overlying water column. 
The ratio of phosphorus to nitrogen in the water column declined as a 
function of salinity and it appears that phosphorus declined more sharply than 
would be predicted from mixing of different water types (i.e. P was removed 
from the water column) whereas there was no indication of a net demand for 
levels often low and the
nitrogen. Even though inorganic nitrogen were very 
limited the
potential for phytoplankton growth may have been by supply of 
nitrogen, it is possible that the supply of phosphorus could ultimately exert an 
important control on productivity of the system. More study on nitrogen-
phosphorus relationships is clearly warranted. 
Benthic Respiration Rate and Ammonium Flux: 
Two methods were used to assess benthic respiration and nutrient 
regeneration. An experimental approach was employed to measure the changes 
of and ammonium concentration in natural water enclosed in a chamber
oxygen 
over the sediment. These measurements were time consuming and technically 
challenging. They were performed during each sampling period at only one 
station (85). The flux of ammonium from the sediment was also estimated 
indirectly by calculating diffusion out of the sediments based on vertical 
profiles of pore-water ammonium concentration and assumptions about 
diffusivity in the sediments and boundary conditions at the sediment-water 
interface. Ammonium in the pore-waters was determined at most stations. 
Through the seasons, dissolved oxygen concentration was higher in 
relatively wet Year 1 as compared to the dryer Year 2. The percent oxygen 
saturation also followed a similar pattern. 
Benthic respiration was monitored during chamber experiments. Benthic 
respiration rate was not significantly related to temperature or to salinity 
during the two year period. 
Results from benthic chamber experiments showed that ammonium flux 
from the sediments for Year 2 was than Year 1 for all months
greater except 
March 1985 when a very large peak of 2000 mg-at N m was measured. 
Ammonium flux was found to be from the water column into sediments rather 
than from sediments to the water column or was not significantly different 
from zero on three sampling trips in Year 1. Rough calculations show that the 
demand for nitrogen in the water column is on the same order
the regenerated 
of magnitude as the benthic flux typically measured in the chambers. 
The vertical pattern of porewater ammonium was unusual in the wet Year 
1; maximum concentration often in the 1 at as has
was upper cm, not depth 
been regularly observed during similar studies. This unusual pattern of 
ammonium in the sediments may have been related to nutrient loading, 
resultant production, and deposition of nitrogen. During Year 2, when 
freshwater input was less and nutrient and chlorophyll concentrations were 
lower than in Year the reservoir of ammonium in the few cm of
1, upper 
sediment declined and pore water ammonium concentrations generally increased 
with sediment depth. The reservoir of ammonium in the sediments was thus 
much greater during year 1, when freshwater input was greater. Because other 
forms of dissolved nitrogen were not measured and transformations of nitrogen 
species were not assessed, it is difficult to draw firm conclusions from the 
data on porewater ammonium. Even though the pool size of total nitrogen in 
surface sediments and the main processes related to ammonium remineralization 
are unknown, we can state that the ammonium pool in surface sediments 
seemed to be responsive to freshwater inflow. 
A substantial discrepancy existed between . calculated and measured 
ammonium flux. This discrepancy was due to excessively high calculated fluxes 
resulting from the arbitrary assumption made when ammonium concentration 
was maximal in top sediment section. Therefore, ammonium flux measured 
reliable estimate than calculated
from the chamber experiment is a more 
(theoretical) flux in this study. 
calculated show
Although neither measured nor flux a significant 
flux related to
relationship to temperature, and measured was not significantly 
salinity, calculated flux did decrease as salinity increased at station 85. 
Higher ammonium concentration of top sediment pore waters in Year 1 (wet 
year) relative to those in Year 2 (dry year) seems to be responsible for such a 
relationship. 
Zooplankton: 
Zooplankton occurrence and abundance in upper and lower Lavaca Bay 
were affected by freshwater events and seasonality. Flood events in the 
estuary resulted in the physical displacement of estuarine zooplankton with a 
population of freshwater species. In most cases it seemed that the 
displacement was transient and salinity increases allowed estuarine species to 
recolonize quickly. 
Although freshwater inflows were higher in Year 1 than Year 2, there 
was no difference in the standing crop between the two years. Seasonal 
cycles in the upper bay are difficult to discern because of sporadic freshwater 
input and displacement of populations. The seasonal highs of standing crop 
occurred during one of the summer months in each year. 
Zooplankton dry weight biomass generally followed zooplankton standing 
crop measurements. Biomass measurements in Year 2 indicated that the 
estuary was organized into zones grading from low salinity areas, with low 
zooplankton biomass and presumably low productivity, to a zone of higher 
salinity and a higher biomass of marine species. There was an intermediate 
zone where estuarine species predominated. This was also the zone of highest 
zooplankton standing crops. This middle-bay region, which moved some with’ 
periodic freshwater events, had relatively stable salinities and represented a 
buffer between the low salinity regime and the marine zone. The extent to 
which marine species range into the middle and upper bay is dependent on the 
salinity gradient established by freshwater inflow. It is concluded that the 
distributions of freshwater, estuarine and marine zooplankton species were 
quite responsive to physical forcing associated with freshwater input. 
The body length of the dominant estuarine zooplankter, Acartia tonsa, 
was measured systematically. There was a significant positive correlation 
between body length and salinity. Two distinctly different populations of this 
species may occur in the same estuary or else the size variations are due to 
other environmental factors. Secondary productivity was not assessed 
during 
this study. 
Benthos: 
Very little change was seen in the concentrations of benthic organisms 
between Years 1 and 2. The vertical distribution of infauna in the sediment 
was typical for this type of estuary. Highest concentrations of organisms were 
found in the upper 3 cm. Numbers declined with depth to the lowest 
concentrations at 10-20 cm. 
Although abundances changed little between years, benthic biomass did 
show a pattern, with an overall increase in biomass for Year 2. Biomass, 
unlike individual abundance, increased with depth. The largest biomass 
measurements were in the 10-20 cm stratum. The molluscs, Mulinia lateralis 
and Macoma mitchelli, had an overwhelming effect on these patterns of benthic 
biomass. 
Any relationship between freshwater input and benthic biomass will 
the nature of the effect (e.g. enhanced survival and growth, or
depend on 
perhaps restricted recruitment) and the generation times of the benthic 
organisms. Influences of freshwater input on recruitment might show up 
months later in the biomass of a cohort whereas effects of freshwater inflow 
on or survival should reflect conditions over an extended
growth average 
period, possibly offset by a lag. Simple correlations between infaunal biomass 
and short-term stream flow are not to be expected, except in special cases. 
The only species which were affected by inflow on a short were the
term 
aquatic chironomid larva which had a lagged response to inflow and the 
polychaete, Hobsonia florida. 
Finfish and Shellfish: 
The purpose of this component was to provide data on the utilization of 
the Lavaca River delta as a nursery habitat for finfish and selected macro-
invertebrates. 
the
As is typical of fish populations, a small number of species comprised 
bulk of the population. The seven most abundant species accounted for 75% of 
the total number of individuals collected. Cluster analysis yielded a significant 
temporal grouping of three "seasons". These seasonal distribution patterns 
were relatively consistent between the two years despite significant differences 
in salinity. Spatial patterns were a minor factor in groupings shown by cluster 
analysis. 
It is concluded that the primary factor influencing changes in fish species 
composition in the Lavaca River delta is the sequential arrival and departure 
of postlarval and juvenile fishes and invertebrate species. Salinity effects 
were seen only as a minor perturbation within these major temporal patterns. 
The data show that the Lavaca River delta is utilized extensively as a 
area by most estuarine dependent species which are of commercial or
nursery 
recreational importance in the Gulf of Mexico. There are also numerous other 
species utilizing the delta as a nursery area, many of which are important 
components in the food web leading to commercial or recreational species. 
The seasonal pattern is, therefore, a reflection of spawning times of 
these species utilizing the delta as a nursery. In general, the "seasons" 
include the juveniles of winter spawners in March-June and the spring and 
early summer spawners in July-October, The low number of species spawning 
in late summer are reflected in the relatively low diversity of the November-
February period. 
Stable Isotopes: 
The objective of the stable isotope studies was determine the
to extent 
of utilization of river-transported organic matter by the biota of the 
system. 
This was to be accomplished by applying a mixing model to infer carbon 
13 
sources based on different 8 C characteristics of organic carbon from marine 
and terrestrial sources. The model indicated that substantial river-transported 
C3~higher plant organic carbon is being taken up and assimilated by organisms 
13
• 
the Lavaca
m Bay ecosystem. Strong correlations between 8 C and distance 
of collecting station from the river were shown by sedimentary total organic 
matter, total infauna, total bivalves and net zooplankton; moderate correlations 
and Acartia weak
were shown by total fish, total shrimp lonsa; correlations 
matter.
were shown by dissolved and particulate organic 
from showed less
As might be expected, samples Matagorda Bay always 
higher plant influence than did Lavaca Bay samples. This difference is 
probably a good measure of the importance of river transported organic matter. 
Fish as a group seemed to be related to phytoplankton in both bays while 
shrimp showed a definite river/higher plant signal. Acartia tonsa, an estuarine 
copepod, reflected a higher plant based food-web, possibly based on a detrital­
microbial pathway. 
13 
While 8 C data provides no information on the number of animals 
abundance
utilizing a given source of carbon, when combined with and 
distribution data from other studies, it permits an assessment of the relative 
importance of organic carbon from different sources. The study area was 
found to have diverse food-webs with animals utilizing both the river and bay 
as sources of nutrition. 
Comments and Conclusions 
This was not a process-oriented study but many insights into processes 
were obtained. The results of the study have stimulated many suggestions for 
future research. Some have been incorporated into a follow-up program in San 
Antonio Bay. 
A few topics deserve mention. Primary productivity (including 
photosynthesis as a function of light) should be measured regularly. A special 
effort should be made to assess any physiological differences associated with 
salinity and perhaps nutrient input. Primary production by the 
microphytobenthos should be assessed as well as the effects of resuspension. 
Almost nothing is known of the proximate fate of primary productivity nor the 
relative importance of different paths of nutrient regeneration, even though 
very close coupling of growth and grazing of phytoplankton is indicated. 
Filter feeding by benthic macrofauna, including patchily-distributed oysters, 
be important. Further work should be done on methods to measure
might very 
fluxes at the sediment-water interface. Rates of nutrient transformations 
should be measured as well as pools and fluxes of dissolved organic nitrogen. 
Secondary production should be estimated and related to freshwater input via 
primary production. Growth rates of fish should be estimated to evalute the 
estuary as a nursery. Stable isotope studies should use two tracers to reduce 
analytical ambiguity. 
While keeping in mind the large quantity of useful information that was 
obtained during this study, it is useful to examine some of the limitations, too. 
The sampling scheme that was chosen for this study determined the types of 
relationships that could be effectively observed. The temporal scale (1-2 
months between samplings) was too coarse to observe the dynamic relationships 
between nutrient injections and uptake by phytoplankton. Also, it was not 
possible to quantify the importance of sediment resuspension in redistributing 
the autotrophic community. Analytical problems plagued measurements of 
benthic nutrient regeneration to the extent that modification of sampling 
frequency is not a priority. The sampling schedule seemed to be appropriate 
for documenting the influence of freshwater, especially flood events, on the 
distributions of zooplankton. However, measurements of standing crops of 
zooplankton do not convey a compreshensive description of secondary 
productivity. Relatively slow-growing benthic infauna were sampled fairly well 
(with notable exception of oysters), but the length of the record (2 years) was 
' 
too short to document many possible relationships between freshwater input 
and the benthic community. Because mechanisms of freshwater influence are 
not specified, it is difficult to know what correlations and what lag periods 
should be expected. The sampling frequency was adequate to document the 
seasonal utilization of the river delta by fish and it was shown that the 
distribution of fish was not very sensitive to changes in salinity. The 
importance of freshwater to the estuary as a nursery was not assessed 
comprehensively, however, because growth rates and survival were not 
determined. Stable isotope studies are inherently immune from some problems 
of sampling scales, because the organisms integrate their own environment on 
scales appropriate to them. Highly mobile organisms might frustrate some 
analyses, because their movements prior to sampling cannot be specified. 
One approach to assessing the influence of freshwater on an estuary 
would be to obtain a very long time series (20 or more years) of finfish and 
shellfish abundance and correlate the data with freshwater inflow and other 
pertinent parameters. Analysis might not be straightforward because of 
unnatural external influences. Also, the influences of physical forcing would 
be data would be value
not described mechanistically. The set of great 
nonetheless. 
Despite some inherent limitations, this study was successful in describing 
many responses of an estuarine system to freshwater input. Directions for 
further study were clearly indicated. 
REFERENCES 
Haury, L.R., J.A. McGowan and P.H. Wiebe. 1979. Patterns and in
processes 
the time-space scales of plankton distributions. In: J.H. Steele, (ed.), 
Spatial Patterns in Plankton Communities. Plenum. 
Lewis, M.W. and T. Platt. 1982. Scales of variability in estuarine ecosystems. 
In; V. Kennedy (ed.). Estuarine Comparisons. Academic. 
CHAPTER I 
INTRODUCTION 
A two year study to monitor the effects of freshwater inflow on 
selected sites in the upper portion of the Lavaca-Tres Palacios Estuary and 
conducted November
parts of Matagorda Bay was from 1984 through August 
1986. Increasing freshwater demands for industry, municipalities, agriculture, 
and recreation have made provision of sufficient freshwater inflow to maintain 
maximum production in Texas bays and estuaries a major One means
concern. 
of allocating freshwater among competing users is the construction of dams on 
the rivers which supply Texas estuaries; e.g. the Navidad River which was 
dammed in May 1980 to form Lake Texana. This reservoir was constructed to 
supply water for industrial and municipal use and was not intended for flood 
control. Major floods are allowed to pass through the flood gates and 
inundate the marsh system associated with the Lavaca-Navidad River delta. 
The upper Lavaca Bay and Matagorda Bay (Fig. 1.1), located at 
latitude 28°40’ North and longitude 96°36’ West, is part of one of the seven 
major estuaries along the Texas coast. Lavaca Bay is a shallow estuary with a 
maximum natural depth of about 2.4 m and a surface area of about 16,576 ha. 
The perimeters of the upper bay shorelines are lined with patchy Spartina and 
the surrounding low salinity marshes are vegetated mainly with Juncus 
downriver and Phragmites upriver. The majority of freshwater inflow into 
upper Lavaca Bay comes from the Lavaca and Navidad Rivers, while lesser 
contributions come from Venada, Garcitas and Placed© creeks. Circulation 
between the upper and lower bay is modified by the presence of highway
state 
35 the remains of the old and the presence of 
causeway, causeway, 
Chickenfoot Reef which extends from the west side of the bay parallel with 
the Marine influence enters through Pass Cavallo and the 
causeway. 
Matagorda Ship Channel. 
Two small tertiary bays or lakes are associated with the Lavaca 
River. Redfish Lake (Station 603) is approximately 4.8 km (3 miles) and Swan 
Lake (Station 613) is approximately 1.6 km (1 mile) north of Lavaca Bay (Fig. 
1.1). Redfish Lake is about 194 ha (0.75 and Swan Lake is about 259 
ha (1 Both lakes are shallow with a maximum depth of about 1.2 m. 
The salinity of Redfish Lake is usually similar to the river’s while the salinity 
in Swan Lake is more estuarine due to its proximity to and its connection to 
Lavaca Bay via Catfish Bayou. Parts of the study area description were 
derived from previous work by Gilmore et al., 1976. 
Historically, upper Lavaca Bay has been mainly supplied with 
freshwater from the Lavaca and Navidad Rivers. The forty-five year daily 
flow for the Lavaca River is 334 cubic
average feet/second and the forty year 
daily flow average for the Navidad River is 572 cubic feet/second (U.S. 
Water Data
Geological Survey Report). Daily mean stream flow into Lavaca 
Bay from 1975 through 1986 is illustrated in Figure 1.2. Freshwater inflow 
rates from gauge 08164000 on the Lavaca River near Edna, Texas indicates that 
the average daily flow rate for Year 1 of this study was 357 cubic feet/second, 
50% higher than the daily average of 177 during Year 2. Since the closing of 
the dam on the Navidad River in May, 1980 the freshwater inflow has
pattern 
been altered, although it has not deviated much from the historic flow rate of 
572 cubic feet/second. The average stream flow from January 1983 through 
1986 demonstrates cyclic inflow from year to year (Fig. 1.3). A wet cycle 
3 
in to 1this
occurred in 1983 followed by a dry year 1984 prior Year of study 
which was another wet Initial filling of Lake Texana from May 1980' 
year. 
through December 1982 resulted in negligible input from the Navidad; 
Freshwater releases beginning in December 1982 through December 1983 on a 
monthly basis resulted in a daily mean flow of approximately 1,250 cubic 
feet/second, which is above average. January 1984 through December 1985 was 
a drier period with sporadic discharges in January, May, and October 1984 
averaging 340 cubic feet/second/day. From January 1985 through December 
1985 increased inflow was noted with releases occurring every month except 
May, August and September 1985. The daily average flow rate for this period 
was 662 cubic feet/second. Flow rates were down from January 1986 through 
December 1986 with releases only in May, June, and September, 1986, resulting 
in a daily average of 282 cubic feet/second. Lavaca River streamflow was 
averaged for 14 and 28 days prior to and including the first sampling day of 
each trip and correlated with mean salinity data using Pearson Correlation 
Coefficients. The 14 day x flow was significantly correlated with salinity (r = 
-0.55474*) while the 28 day x flow was not significant; therefore the 14 day x 
flow was used to calculate freshwater inflow effects on the benthos in Chapter 
5. An example of the x 14 day inflow and its relation to x salinity is shown 
in Figure 1.4 for November 1984 through August, 1986. 
The objectives of this study were to examine the environmental 
effects of altered freshwater inflow into upper Lavaca Bay resulting from the 
Palmetto Bend Project on the Navidad River and to document the use of the 
Lower River Delta as a area for finfish and shellfish. The study had
nursery 
several components; (1) primary producers and nutrient dynamics, (2) benthic 
nutrient regeneration, (3) zooplankton, (4) benthos, (5) finfish and shellfish 
and (6) natural isotopic studies of organic input in Lavaca Bay. 
Fourteen sampling trips were conducted which included the following 
months: November 1984, January, March, April, May, June, July, August, 
October and December 1985, and February, March, June and August 1986. Year 
1 of the was from November 1984 through 1985 and Year 2 was
study August 
from October 1985 through August 1986. Each sampling trip involved two days 
in Lavaca Bay. The first day’s sampling included zooplankton, ichthyoplankton, 
trawls, chemistry, nutrients, hydrographic parameters, and phytoplankton. 
Benthic respiration chambers and primary production experiments aboard the 
R/V KATY, benthic cores, seine and sled samples were collected on the second 
day. Stations in the lower bay were sampled on the return trip to Port 
Aransas aboard the R/V KATY. 
The first eight trips focussed mainly on stations located in the 
upper part of the bay north of state highway 35. The sampling sites in Figure 
1.1 included stations 45 and 65 603, 613, 623 85
(river sites), (lake sites), 
(river delta) and 633 (upper bay). Two additional stations, 1505 and 1905 were 
sampled for nutrients, hydrography, and phytoplankton. Benthic respiration 
chambers were deployed only at station 85. 
the last 8 stations and south
During trips 1,2, 3, 1505, 1905 35-36 
of highway 35 were added for zooplankton. Stations 65, 613 and 623 for 
isotope analyses were discontinued and stations 1505, 1905 and 35-36 in the 
lower bay were added to increase coverage over a greater salinity range. 
Support vessels included the R/V KATY, a 58’ fiberglass trawler 
which was anchored at station 85 for laboratory space and berthing, a 21’ Skip 
Jack, and a 16’ Boston Whaler. 
ACKNOWLEDGEMENTS 
Our appreciation is offered to the following collaborators for their 
field sampling efforts, laboratory work up, and cooperation in making this 
project successful: Amy Whitney, Hugh Mclntyre, Carolyn Miller, Don Pierson, 
Zhu Mingyuan and Chris Schneider (Nutrient Dynamics and Primary 
production), Judy Lee (Nutrient Regeneration), Lynn Tinnin, Julie Findley and 
Wen Lee (Zooplankton and Benthos), Dee Fajardo, Li Maotang, Wen Lee 
(Finfish and Shellfish), Richard Anderson and Della Scalan (Isotopes and Marsh 
Plant Input), Hayden Abel, Noe Cantu, Don Gibson, John Turany, Billy 
Slingerland (Boat Crew), and Helen Garrett (Word Processor Operator). Special 
Paul and
thanks also are due Dr. Ed Buskey, Dr. Montagna Dr. Terry Whitledge 
for technical input and assistance on construction of several of the chapters. 
RobLaneprovided aconsiderableamountofdatamangaementforthisproject. 
REFERENCES 
N. 1976.
Gilmore, G.H., J. Dailey, M. Garcia, Hannebaum, J. Means. A study of 
the effects of fresh water on the plankton, benthos, and nekton 
assemblages of the Lavaca Bay System, Texas. Tex. Pks. Widlf. 
Dept., Coastal Fish., Div. Tech. Rep. to the Tex. Wat. Dev. Bd., 113 
P­
Figure 1.1. Map of Lavaca Bay study area, with sample stations indicated. 
7 
1985 
through' 

1975 from year 
by 
Bay 
Lavaca 
into flow River 


Lavaca-Navidad 

daily 
Average 

1.2. Fig. 
8 

January 

from month 
by 
Bay 
Lavaca 
into flow River 
1986.



Lavaca-Navidad 

August daily 
throughAverage 1983 
1.3. 

Figure 
9 
its 1984 each 377, and with 

trip November 926, 
424,

sampling corresponding
from 63, 
ft/sec.
month 
cu 

each follows: 
byto 15

streamflows 

are
prior stations as and average 1984 258, 
all
average 
32, 
for day 
43,

day October 
14 
The in
salinity14 521, 
streamflow 1986. starting 33, 
average 19, 
August trip 349,
to
River 
97, 
Lavaca relation through sampling 1913, 
1.4. 
Figure 
CHAPTER 2 
NUTRIENTS, HYDROGRAPHIC PARAMETERS 
AND PHYTOPLANKTON 
1984 1986

-
INTRODUCTION 
This component of the study was designed to observe spatial and temporal 
patterns of nutrients and phytoplankton in the Lavaca Bay estuary and to 
interpret the observations with respect to the influence of freshwater input on 
primary production. Strong patterns were found, and these could often be 
related to the influence of freshwater. Sampling was inadequate to examine 
properly some relationships such as interannual correlations of nutrients and 
salinity. Also, the statistical relationships that are documented cannot be 
interpreted as demonstrations of causality. It is thus inappropriate to make 
generalizations about some patterns which seem obvious. Nonetheless, the data 
allow instructive comparisons between a wet year and a dry year and between 
sites along a salinity gradient. 
METHODS 
Sampling sites and schedules are described in the introduction. Data 
described below were obtained concurrent with zooplankton and nekton 
sampling. Upon occupation of the station, air temperature, wind, and cloud 
-
cover were recorded, followed by determination of Secchi depth. A Hydrolab 
sonde (Hydrolab, Austin, TX) was used to measure pH, conductivity, 
temperature, and dissolved oxygen at the surface. The same measurements 
were often made at one or more depths below the surface. A water sample of 
about 2 liters was taken by submerging a clean, rinsed polycarbonate bottle 
just below the surface. This sample was used for the measurements of 
nutrients, organic material, pigments and phytoplankton. Duplicate samples 
were taken at each site, separated by about 20 minutes. 
During the 1984-1985 sampling year, salinity was calculated from 
conductivity on the basis of laboratory calibrations of the Hydrolab sensor. A 
dilution series of seawater was prepared and salinity was determined on a 
Beckman Pers. and
oceanographic salinometer (A. Amos, comm.) compared 
statistically to conductivity as measured by the sensor. The empirical formulas 
(Table 2.3) are sensor-specific and not intended for general application. 
During the 1985-1986 sampling year, salinity was calculated from temperature-
compensated conductivity using the practical salinity scale (UNESCO, 1978). 
Note that measurements of salinity below 2-3 ppt in an estuarine environment 
may be neither accurate nor particularly meaningful (Mangelsdorf, 1967) and 
that salinity should be reported in dimensionless units, not ppt as we have 
done in this report. The determination of salinity is discussed in a TWDB 
interoffice memorandum (G. Powell, March 3, 1986). 
Dissolved nutrients were measured on filtered and frozen samples. 
Immediately after sampling, water was filtered through a 47mm glass-fiber 
with
filter and, after appropriate rinsing of the containers filtrate, poured into 
a carefully cleaned 265 ml polycarbonate bottle for storage on dry ice and 
then in a freezer. Ammonium (phenol-hypochlorite method, in duplicate), 
phosphate, nitrate (cadmium reduction) and nitrite were determined as in 
Parsons et al, (1984). Filtration and freezing of samples is preferable to 
transporting whole water to the laboratory. The tenfold-higher concentrations 
the
of ammonium found in a prior study of region (Gilmore et al., 1976) are thus possibly attributed to artifact. Our method of filtering and freezing prior 
to analysis is better than those used previously but they are not optimal; it is 
generally held that ammonium measurements on frozen samples are unreliable 
and that can used for critical of
only fresh samples be measurements 
ammonium concentration. Uncertainty associated with freezing may be on the 
order of .5 ug-at/1 (.007 mg/1 N/l), not much of a problem in the context of 
this study. 
Total Kjeldahl Nitrogen was determined by W. M. Pulich, Jr. on whole-
water samples poisoned with HgCl2 and stored at 2°C. Total phosphate 
(persulfate digestion in an autoclave) was measured, usually in triplicate, on 
whole-water samples stored at 2°q. For unknown reasons our measurements of 
total phosphate tend to be about twice as high as those reported by Gilmore 
et al. (1976) for the Lavaca Bay region in 1973-1975. 
Samples were collected on Whatman GF/F filters (o.7um nominal 
retention) and extracted in 90% acetone for duplicate fluorometric 
determinations of chlorophyll a and pheopigment (Parsons et al., 1984). Values 
for chlorophyll and pheopigment from the progress report for 1984-85 have 
been corrected for a calibration error. Pheopigments are reported in 
chlorophyll equivalents. Because of interference from pigments such as 
chlorophyll b (Lorenzen and Jeffreys, 1980) and problems associated with 
incomplete extraction of some taxonomic forms in acetone (Holm-Hansen and 
Riemann 1978), pigment data should be viewed with some caution. When 
comparing these pigment data with other studies, pore size of filters should be 
noted, as significant proportions of phytoplankton biomass can pass filters of 
um pore size and larger. 
for with
Samples phytoplankton enumeration were preserved Lugol’s 
solution and settled for observation with an inverted microscope at IOOx and 
400 x magnification. Representative cell dimensions for each common form was 
recorded and biovolume calculated by geometrical approximation. Cell counts 
reported here are higher than what might be found in earlier studies because 
the abundant and very small (<sum) forms were counted. There is a systematic 
difference between the counts for Year 1 and Year 2 attributable to 
differences in the counts for extremely small phytoplankton. This is because 
the two operators had different "thresholds" for counting the smallest cells. 
Therefore the two years cannot be legitimately compared for total cell counts 
or biovolume. Although many small phytoplankton can be discerned with the 
inverted microscope, a technique such as epifluorescence microscopy is needed 
for accurate assessment of autotrophs in the o.sum-2um range (Johnson and 
Sieburth 1979). Methods used in this study have probably yielded 
underestimates of the smallest phytoplankton in Year 2 as well as in Year 1, 
even though some heterotrophic bacteria may have unavoidably been confused 
with cyanobacteria in the counts from Year 2. 
The data were subjected to a variety of statistical analyses, including 
linear regression, one-and two-way analysis of variance (parametric and 
nonparametric), nonparametric correlation, Tukey’s HSD test, and the Mann-
VVhitney U test. Missing values and violations of the assumptions of 
parametric statistics plagued the analysis, and thus the statistical presentation 
is limited. The results presented here were generated by SYSTAT for the 
the
Macintosh (Wilkinson, 1986), except regressions, which were generated by 
Cricket Graph. 
G.
Field sampling was performed by Amy Whitney, Hugh Maclntyre, and 
Sung R. Yang. Ancillary experimental work was carried out by Zhu Mingyuan 
and Richard Davis. Don Pierson and Zhu Mingyuan supervised analytical work 
early in the study. Enumeration of phytoplankton was done by Amy Whitney 
in Year 1 and Barbara Cullen in Year 2. 
RESULTS 
Annual Pattern 
A graphic presentation of the data demonstrates very clearly the 
dominant patterns during the study. Year 1 (1984-1985) was relatively wet and 
Year 2 (1985-1986) was relatively dry. A salinity gradient, associated with 
proximity to freshwater input, was evident throughout the study period (Fig. 
2.2). Nitrate concentration (Fig. 2.8) seemed to reflect the importance of 
freshwater input to nutrient dynamics. High concentrations were associated 
with low salinities and concentrations were very low in the dry year, and at 
the bay stations as compared to the upriver stations. The general picture is 
one of freshwater input having a very important influence on nutrient 
concentrations. A more detailed examination of the data provides additional 
insight and some information on biological utilization of the nutrients 
associated with freshwater input. 
To examine the relationships between freshwater input, nutrient dynamics 
and primary production on a scale appropriate to fisheries, it would be useful 
to compile a long record and correlate annual averages of salinity, nutrient 
concentrations and biological responses. We only have two years to work 
with, one wet and one dry, we cannot confidently ascribe statistically 
significant differences between years to freshwater influence. It is useful to 
compare the two years nonetheless. 
Stations 1505 and 1905 "were least influenced by freshwater and most 
afflicted with missing values, they were excluded from the statistical’ 
comparison of Year 1 vs Year 2 (Mann-Whitney U test. Table 2.1). Comparison 
of the from the remaining stations (Table 2.1) showed substantial
parameters 
differences between that are in most cases evident in graphical
years 
in
presentation (Figs. 2.1-2.13). The water was indeed fresher Year 1 (pc.001) 
and the concentrations of dissolved nutrients, excluding ammonium, were 
substantially higher in the wet year (pc.001), as was total phosphate. Pigment 
concentrations were significantly higher in the first year, consistent with, but 
not demonstrating, higher primary production. Total Kjeldahl nitrogen (TKN) 
did not behave the same as other measures of nutrient loading: concentrations 
were higher in the second year. Nitrate and nitrite are not measured by the 
Kjeldahl method. Total nitrogen, here defined as TKN + nitrate + nitrite, was 
and
not significantly different between years. Nitrogen phosphorus dynamics 
are discussed below. 
It is reasonable to expect that enhanced flushing associated with 
freshwater input would increase turbidity due to sediment resuspension and 
transport. The relationship was obvious to the sampling party and is 
represented by the differences in Secchi depth between Year 1 and Year 2 
(Fig. 2.5). If phytoplankton biomass is held steady or is flushed away, 
increased turbidity from freshwater input will reduce water-column primary 
productivity. If the nutrient load associated with the freshwater input (Figs. 
2.18, 2.19) is converted to biomass, though, productivity on an areal basis will 
depend on the relationship between turbidity and nutrient load. If physical 
forcing is reduced, particulates can settle out of the water, leaving dissolved 
nutrients in a more water column and setting the for
transparent stage 
model of
enhanced primary productivity. A comprehensive light-nutrient 
relationships is beyond the scope of this study. Light and nutrient limitation 
of productivity are briefly discussed below. 
Seasonal Pattern 
The most obvious seasonal pattern was in temperature (Fig. 2.1), which is 
certain to influence rates of biological utilization. Many of the other 
measured parameters showed significant variation between months (i.e. sampling 
periods; Table 2.2), but simple seasonal variation is difficult discern, in
to 
large part because inferred freshwater input did not show a simple annual 
cycle. 
For example, freshwater events in November 1984 and July 1985 were 
scarcely noticeable in the record of nitrate concentration (Figs. 2.2, 2.8), 
whereas similar patterns of salinity were associated with relatively high 
concentrations of nitrate during the spring of 1985 and December 1985. 
Temperature alone cannot explain the contrast, as waters were cool (about 
15°C) in November 1984 and near 30°C in July 1985. Perhaps biological 
demand for nutrients builds up during the summer and fall and declines sharply 
in the winter. Measurements of chlorophyll are consistent with such an 
explanation. In November 1984 and July 1985, chlorophyll concentrations were 
higher upriver (Fig. 2.12), indicating that biological utilization of freshwater-
associated nutrients had occurred. When high nitrate concentrations were 
observed in low-salinity water during the spring of 1985, chlorophyll was more 
concentrated downriver, indicating that flushing of the bay system can force a 
temporal and spatial separation of nutrient input and biological utilization. 
Such a simple explanation cannot be supported by the data on hand because we 
have no information on the temporal development of nutrient-salinity 
relationships on the scale of days after a runoff event. The low-nutrient/high 
be to
biomass/low-salinity pattern of November 1984 might due primarily the 
long interval (3-4 weeks) between a major freshwater event and sampling as 
compared to the high-nutrient/low-biomass/low-salinity pattern that would be 
found as the bay was being flushed out by runoff. 
We conclude that available data are insufficient to resolve questions 
concerning seasonality in nutrient utilization, not only because of the 
complexity of the relationships but because the patterns of nutrients as related 
to salinity are almost certainly strongly affected by the time of sampling after 
a freshwater input event. 
Spatial Patterns 
Compared to the range of replicate determinations, differences between 
the most
station means in study area were clearly significant for parameters 
(see Figs. 2.1-2.14). Seasonally consistent differences between stations can be 
discerned with two-way analysis of variance (Table 2.2). When spatial patterns 
across the environmental gradient differ according to sampling period (as was 
clearly the case for chlorophyll: compare November 1984 and early spring 
1985), interpretation of results must be modified. Because the data record is 
too short to resolve statistically any consistent temporal differences in the 
spatial patterns of nutrients and suspended or dissolved organic material, we 
cannot specify where and when nutrients are utilized maximally in the upper 
estuary. It seems clear, however,-that the influence of nutrient input on the 
lower bay is largely indirect, as high concentrations of nutrients are confined 
to the sites closest to sources of freshwater. 
Nutrient Interactions 
It is sometimes desirable to try to specify a single factor which limits 
production in a given aquatic ecosystem. Nitrogen is commonly identified as 
such a factor, i.e. the limiting nutrient. The simplified picture is that 
production will be proportional to the supply of nitrogenous nutrients and 
independent of other variables. If the supply of the nitrogen exceeds a 
threshold, some other nutrient, such as phosphate, might limit production, or 
perhaps biomass levels will increase to the point that light limits 
photosynthesis. Experimentally, the N-limited system should respond to added 
nitrogen alone and should be insensitive to other nutrients or increased light 
availability in the absence of added nitrogen. To be valid, controlled 
matter.
experiments should be on the ecosystem scale, clearly not a simple 
During this study, in higher salinity water, the concentrations of 
nitrogenous nutrients were often near the limit of detection whereas levels of 
dissolved phosphate were low but detectable—high enough to support additional 
algal growth if nitrogen were available (Figure 2.20). The pattern is consistent 
with nitrogen-limited primary production in the estuary. Experimental evidence 
to support this conclusion is lacking, however. One might also wonder why 
nitrogen should limit production in an environment where nitrogen fixation 
might make an important contribution to nutrient dynamics. 
The question of nutrient limitation on the ecosystem scale can be 
addressed by mass-balance analyses (Smith, 1984, Smith et al. 1984). It is 
argued by S. Y. Smith that if a system has a net demand for phosphorus and 
exports nitrogen, it must be limited by P rather than nitrogen. Smith has 
discussed oligotrophic environments in which the data indicate that N is not 
limiting. The nature of the Lavaca Bay estuary is such that the assumptions 
of the mass-balance analysis are not satisfied (see Smith, 1984), but it is 
instructive nonetheless to discuss patterns of N and P during the study. 
Dissolved phosphate, nitrate, and total P concentrations were lower in the 
dry year and in higher-salinity water, consistent with biological utilization of 
N and P and net deposition of P in the estuary (Figs. 2.20, 2.21). Total 
Kjeldahl nitrogen (organic N and ammonium) weakly shows an inverse pattern, 
apparently reflecting the conversion of nitrate to organic nitrogen and little or 
no net deposition of N in the study area. Accordingly, total N (nitrite + 
nitrate + TKN) shows no consistent relationship with freshwater but the ratio 
(Total P/Total N) declines rather sharply with salinity (Fig. 2.21). Little is 
known as to what determines the chemical composition of the salty end-
member of the estuarine water, so non-conservative behavior of phosphorus has 
been clearly demonstrated. Thus, the patterns of N and P observed during this 
study do not justify any firm generalizations. Nonetheless, the apparent 
relationship between the two nutrients is provocative. It can be inferred from 
the relationship between N and P that any losses of N associated with the loss 
P of
of to the system (i.e. by deposition organic material) are more than 
compensated by processes which act on N but not P, for example nitrogen 
fixation. The relatively high concentration of TKN in the dry second year is 
consistent with this scenario. 
Denitrification can be an important loss term in the estuarine nitrogen 
cycle. At the Lavaca Bay study site, denitrification as well as organic 
deposition was apparently compensated. 
A net demand for P in a system does not demonstrate P limitation. 
but
Nitrogen may limit primary production proximately, phosphorus input, if 
restricted, might ultimately limit production in the system. If freshwater input 
were restricted to the extent that dissolved inorganic P concentrations 
declined to near the limit of detection, one might expect to see some 
the the Lavaca
fundamental changes in dynamics of Bay estuarine system. 
Focussed study on nitrogen-phosphorus relationships could be fruitful. 
Light-Nutrient Interactions 
If only primary production is considered, the subject of light-versus 
nutrient limitation can be approached. The distinction is not as simple as it 
sounds. Consider a well-mixed water column typical of the upper Lavaca Bay 
where the depth is equal to the 1% light level. The average light intensity is 
21% incident (assuming uniform extinction of light with depth). Primary 
productivity is dependent on incident light and sensitive to changes in the 
of the water A model and
clarity (Fig. 2.22). simple of light primary 
productivity demonstrates that light limits primary productivity at times in 
many parts of Lavaca Bay (Tables 2.31, 2.32). 
as not
Light-limitation of primary productivity, described above, does 
exclude nutrient-limitation. Concentrations of nitrate and ammonium were 
in Lavaca and that
generally very low Bay there were indications an increase 
in chlorophyll concentration was one of the responses to nutrient input. It is 
thus reasonable to suggest that the net increase of phytoplankton is limited by 
nitrogen even if it is not possible to assess the nutrient-limitation of 
phytoplankton growth rates. Independent of changes in light, an increase of 
phytoplankton biomass in a well-mixed water column will lead to a nearly 
proportional increase in production (note that light absorption by 
phytoplankton accounts for a small percentage of light extinction in the muddy 
waters of Lavaca Bay). Primary productivity can thus be limited by light and 
nutrients. 
Phytoplankton 
The quantitative importance of very small phytoplankton in marine and 
estuarine systems has only recently been fully appreciated due to the advent of 
epifluorescence microscopy (Johnson and Sieburth 1979; Krempin and Sullivan 
in
1981). Because epifluorescence microscopy was not employed in this and 
previous studies of Texas bays, the phytoplankton assemblages have not been 
fully described. It is thus not surprising that relationships between chlorophyll 
and phytoplankton abundance were not clear: correlations between cell counts 
and chlorophyll were in both as were the correlations between
poor years 
biovolume and chlorophyll. Cell counts were a poor estimator of phytoplankton 
biomass because cell size is not considered. We suspect that the poor 
relationship between biovolume and chlorophyll is due in large part to 
uncertainty in counting and sizing the smallest phytoplankton and also in the 
highly variable chlorophyll content of microalgae (Cullen 1982). The cell 
counts and biovolume estimates from this study are rather poor indicators of 
phytoplankton biomass. The counts do show that small forms are important 
and do contain a substantial amount of information on relative abundance of 
identifiable taxa during the course of the study. An overview of the 
that
taxonomic trends (Figs. 2.16, 2.17; Table 2.30) demonstrates cyanobacteria 
dominated the autotrophic community. Small coccoid cyanobacteria, solitary and 
in small colonies, were by far the most abundant. Clearly, more appropriate 
methods should be employed to look at the autorophs in this estuarine 
community. Epifluorescence microscopy should be employed and extraction of 
pigments into other solvents, as compared to acetone, should be studied. 
Temporal and Spatial Variability 
A proper analysis of temporal and spatial variability in the Lavaca Bay 
estuary would take years and thousands of samples. On the basis of the data 
collected during this study, a few qualitative statements can be made. 
By sampling at the surface, we made the implicit assumption the water 
column was vertically uniform. Profiles made with the Hydrolab sonde at each 
station and thorough at station 85 (Davis, 1986) indicate that the
measurements 
waters in the shallow bay system were almost always mixed top-to-bottom. 
Some stratification was commonly observed at the river stations, however. 
Freshwater introduced to a rather salty bay system formed a lens over the 
river in June 1986, restricting vertical mixing and promoting anoxia below the 
surface at stations 45 and 65. This phenomenon should be considered when 
assessing the impact of intermittent freshwater input to a high-salinity estuary. 
The presentation of the data implies subliminally that each measurement 
is representative of a particular site over the time scale of a month or more. 
Of this has not been demonstrated nor do we believe it to be true.
course, 
Duplicate measurements separated by 20 minutes are very similar, so small 
scale variability is probably not important. Over the course of a day, 
chlorophyll concentration was observed to vary as much as twofold (Figs. 2.23, 
2.24; Davis 1986). Our experience with day-to-day variability is that wind-
induced mixing and sediment resuspension can have a pronounced influence on 
observations. For example, on 3 June 1986, 10:1Oh, the air was calm at 
station 85. Chlorophyll concentration at the surface was 1.67 /xg/1 (Table of 
Chlorophyll values). The wind was blowing on the next day and the 
concentration of chlorophyll at the surface ranged from about 11 to 15 /rg/1 
over the day (Davis, 1986; Fig. 2.24). 
Primary Productivit 
This study was constrained to measure concentrations of organisms and 
rather such
materials than rate processes as primary productivity. Only with a 
systematic program of rate measurements would it be possible to assess 
directly the influences of freshwater input on primary productivity. Even with 
a good understanding of that link, it would be difficult to describe 
mechanistically the ultimate effects of freshwater input on higher trophic 
levels. 
Several experiments were performed at station 85 to examine processes 
associated with primary production. Some results have been presented (Davis, 
1986) but the analysis is not complete. In the results that we have considered 
to date (e.g. Fig. 2.25, Table 2.33), photosynthetic rates normalized to 
chlorophyll compared favorably to healthy cultures. We have seen no other 
indication of severe nutrient limitation of photosynthesis by microalgae. 
Studies of benthic and water-column primary productivity are presently 
underway in the San Antonio Bay estuary. 
The biomass of the microphytobenthos is substantial and distributed well 
below the upper millimeter of sediment where net photosynthesis is possible 
(H.L. Maclntyre, unpubl.). This algal biomass appears to act as a reservoir of 
photoautotrophic potential capable of significant primary production during 
The benthic stations is
resuspension. seasonal pattern of pigments at two 
amount
presented in Fig. 2.26 (H.L. Maclntyre, in prep.). The of pigment in 
the upper 5 mm of sediment is on the same order as that suspended in the 
water column. Novel measurements of photosynthesis vs irradiance on benthic 
samples have demonstrated that the benthic pigments are photosynthetically 
active (Fig. 2.27). The effects of sediment resuspension and the associated 
inoculum of autotrophs on water-column primary productivity are currently 
being studied as part of a research program in the San Antonio Bay. 
CONCLUSIONS 
Measurements of salinity showed that the Lavaca Bay estuary was 
influenced by freshwater. High nutrient concentrations were associated with 
freshwater input and biological utilization of the nutrients was indicated by 
nutrient depletion away from the input and in the dry year as compared to the 
wet year. The flushing action of freshwater inflow was evident during 
sampling periods when nutrients were high and chlorophyll was relatively low 
in low-salinity water. Our results are consistent with the notion that as flow 
subsides, nutrients are utilized and phototrophic biomass increases in the 
fresher water. Thus, there is no reason to expect stable relationships between 
salinity, nutrients and phytoplankton in an estuarine system subject to episodic 
perturbations, at least on the time scale of those perturbations. Over months 
or years though, freshwater input nutrients and primary production are likely 
to be related. The differences between a wet and a at Lavaca
year dry year 
•
Bay are consistent with the proposition that freshwater input has a strong 
influence on primary production. The relationship has by no means been 
proven, however. 
The 
ratio of phosphorus to nitrogen in the water column declined as a 
function of salinity. There is a large amount of scatter in the data, but it appears that phosphorus declined more sharply than would be predicted from 
mixing of different water types (i.e. P was removed from the water column)’ 
whereas there was no indication of a net demand for nitrogen. Even though 
inorganic nitrogen levels were often very low and the potential for 
phytoplankton growth may have been limited by the supply of nitrogen, it is 
possible that the supply of phosphorus could ultimately exert an important 
control on productivity of the system. More study on nitrogen-phosphorus 
relationships is clearly warranted. 
REFERENCES 
Cullen, J.J. 1982. The deep chlorophyll maximum: comparing vertical profiles of 
chlorophyll a. Can. J. Fish. Aquat. Sci. 39:791-803. 
Davis, Richard F. 1986. Measurement of primary production in turbid waters. 
M.A. Thesis. University of Texas at Austin. 
Gilmore, G., J. Dailey, M. Garcia, N. Hannebaum and J. Means. 1976. A study 
of the effects of freshwater on the plankton, benthos, and nekton 
Technical to the
assemblages of the Lavaca Bay System, Texas. Report 
Texas Water Development Board. 113 
pp. 
Harris, G.P., G.D.Haffner and 8.8. Piccinin. 1980. Physical variability and 
phytoplankton communities: 11. Primary productivity by phytoplankton in 
a physically variable environment. Arch. Hydrobiol. 88:393-425. 
Holm-Hansen, O. and B. Riemann. 1978. Chlorophyll a determination: 
improvements in methodology. Oikos 30:438-447. 
Krempin, D.W. and C.W. Sullivan. 1981. The seasonal abundance, vertical 
distribution, and relative microbial biomass of chroococcoid cyanobacteria 
at a station in southern California coastal waters. Can. J. Microbiol. 
27:1341-1344. 
Lorenzen, C.J. and S.W. Jeffrey. 1980. Determination of chlorophyll in 
seawater. Unesco tech, papers in Mar. Sci. 35. 20 pp. 
Mangelsdorf, P.C. Jr. 1967. Salinity measurements in estuaries. In: G.H. Lauff 
(ed.), Estuaries. Publ. No. 83, Amer, Assoc. Adv. Sci., Wash. D.C. pp. 71­
79. 
Parsons, T.R., Y. Malta and C.M. Lalli. 1984. A manual of chemical and 
biological methods for seawater analysis. Pergamon. 
Smith, S.V. 1984. Phosphorus versus nitrogen limitation in the marine 
environment. Limnol. Oceanogr. 29:1149-1160. 
Smith, S.V., W.J. Kimmerer and T.W. Walsh. 1986. Vertical flux and 
biogeochemical turnover regulate nutrient limitation of net organic 
production in the North Pacific Gyre. Limnol. Oceanogr. 31:161-167. 
1978.
Unesco. Background papers and supporting data on the practical salinity
, 
scale 1978. Unesco tech, in Mar. Sci. 37.
papers 
Wilkinson, L, 1986. SYSTAT: The System for Statistics, Evanston, IL: 
SYSTAT, Inc. 
Figure 2.1. Temperature measurements made during the Lavaca Bay study, 
1984-86. Error bars represent range of duplicate samples taken 
about 20 minutes apart. Hydrographic parameters were not 
determined in duplicate during the first 
year. 

Figure 2.2. Salinity measurements made during the Lavaca Bay study, 1984­
1986. Error bars represent range of duplicate samples taken 
about 20 
minutes apart. Hydrographic parameters were not 
determined in duplicate during the first year. 

Figure 2.3. pH measurements made during the Lavaca Bay study, 1984-1986. 
Error bars represent range of duplicate samples taken about 20 
minutes apart. Hydrographic parameters were not determined 
in duplicate during the first year. 
24 
Figure 2.4. Dissolved oxygen measurements made during the Lavaca Bay 
study, 1984-1986. Error bars represent range of duplicate 
samples taken about 20 minutes apart. Hydrographic parameters 
were not determined in duplicate during the first year. 

Figure 2.5, Secchi depth measurements made during the Lavaca Bay study, 
1984-1986. Error bars represent range of duplicate samples 
taken about 20 minutes apart. Hydrographic parameters were 
not determined in duplicate during the first year. 

Figure 2.6.  Ammonium  measurements  made  during  the  Lavaca  Bay  study,  
1984-1986.  Units  are  mg  N/liter.  Error  bars  represent  range  
of duplicate samples taken about 20 minutes apart.  


Figure 2.7. Nitrite measurements made during the Lavaca Bay study, 1984­
1986, Units are mg N/liter. Error bars represent range of 
duplicate samples taken about 20 minutes apart. 

Figure 2.8. Nitrate measurements made during the Lavaca Bay study, 1984­
1986. Units are mg N/liter. Error bars represent range of 
duplicate samples taken about 20 minutes apart. 

Figure 2.9.  Phosphate  measurements  made  during  the  Lavaca  Bay  study,  
1984-1986.  Units  are  mg  P/liter.  Error  bars  represent  range  
of duplicate samples  taken about 20 minutes apart.  


Figure 2.10.  Total  Kjeldahl  nitrogen  measurements  made  during  the  Lavaca  
Bay  study,  1984-1986.  Units  are  mg  N/liter.  Error  bars  
represent  range  of  duplicate  samples  taken  about  20  minutes  
apart.  


Figure 2.11. Total phosphate measurements made during the Lavaca Bay 
study, 1984-1986. Units are mg P/liter. Error bars represent 
range of duplicate samples taken about 20 minutes apart. 

Figure 2.12.  Chlorophyll  a  measurements  made  during  the  Lavaca  Bay study,  
1984-1986.  Error  bars  represent  range  of  duplicate  samples  
taken about 20 minutes apart.  


2.13. made the Lavaca
Figure Pheopigment measurements during Bay study, 
1984-1986. Units are fig chlorophyll equivalents/liter. Error 
bars represent range of duplicate samples taken about 20 
minutes apart. 

Figure 2.14. Phytoplankton cell counts and biovolume estimates made during 
the Lavaca Bay study, 1984-1985. Error bars represent range 
of duplicate samples taken about 20 minutes apart. 
46 
Figure 2,15. Phytoplankton cell counts and biovolume estimates made during 
the Lavaca Bay study, 1985-1986. Error bars represent range 
of duplicate samples taken about 20 minutes apart. 

Figure 2.16 Relative abundance of phytoplankton taxa during the Lavaca 
Bay study, 1985-86. All stations combined. 
50 
Figure 2.17. Relative total biovolume of phytoplankton taxa during the 
Lavaca Bay study, 1985-1986. All stations combined. 
52 
Figure 2.18. Total phosphorus (mg P/l) vs light extinction during the Lavaca 
Bay study. Y 1 = 1984-85, Y 2 = 1985-86. The extinction 
-
coefficient, k (m *), was estimated from secchi depth assuming 
that the depth of 1% surface irradiance is 3x the secchi depth. 
The equation is k = secchi depth/1.54. Regression lines are 
included to show the trends in each 
year. 
54 
Figure 2.19. Chlorophyll (/ig/1) + NO3 (/iM/2) vs light extinction during the 
Lavaca Bay study. Chlorophyll + NO3 is a very rough estimate 
of the potential for light-dependent primary productivity in 
terms of nitrogen. In phytoplankton, 1 fig Chi a corresponds 
“
roughly 0.5 /imole cell nitrogen (C:Chl 50; C:N “7). Y 1 = 
1984-85, Y 2 = 1985-86. The extinction coefficient, k, was 
estimated as in Fig. 2.18. Regression lines are included to 
show the (weak) trends in each One extreme value from
year. 
Sta. 623 in March 1985 has been excluded. 
56 
and Lavaca
Figure 2.20. Phosphorus nitrogen in Bay 1984-1986. Upper 
graph: x dissolved phosphate (mg P/l), filled boxes total 
-
phosphate (mg P/l). Lower graph: x nitrate (mg N/l); filled 
-
boxes total Kjeldahl nitrogen (mg N/l). Note that high 
phosphorus values between 23-30 ppt are from station 1505 and 
1905. Human perturbation of sediments in and near the 
channel is a suspected influence. 
58 
Figure 2.21. Phosphorus (mg P/l) and nitrogen (mg N/l) in Lavaca Bay 1984­
1986. Note that phosphorus values between 23-30 ppt are
high 
from station 1505 and 1905. Human perturbation of sediments 
in and near the channel is a suspected influence. 

Figure 2.22. Light-limitation of primary productivity as a function of water 
clarity and incident irradiance, scaled to that which saturates 
From Table 2.31
photosynthesis. (Cullen, unpubl.). This figure 
shows that when the depth of the mixed layer is greater than 
the 1% level > unit
light (k/z 4.61), photosynthesis per 
chlorophyll in the mixed layer is light-limited. 
62 
Figure 2.23.  Chlorophyll  (filled  diamonds)  and  pheopigment  (open  triangles)  
at  Station  85  at  the  surface  on  April  9,  1986.  From  Davis,  
1986.  

64 
Figure 2.24.  Chlorophyll  (filled  diamonds)  and  pheopigment  (open  triangles)  
at  Station  85  at  the  surface  on  June  6,  1986.  From  Davis,  
1986.  

66 
Figure 2.25. 	Photosynthetic performance of phytoplankton at station 85 in April 1986. From Davis (1986). Photosynthesis vs. irradiance was determined for samples from the surface and
(triangles) bottom (1.4 m; filled diamonds). -These data and other 
measurements showed that the water column was uniform with 
respect to phytoplankton biomass and physiological capacity and that rates of photosynthesis were inconsistent with severe 
nutrient-limitation of growth rate. Data such as these can be 
used to model light-limitation of primary production and to estimate daily primary production in a turbid estuary (Davis el al., in prep.). 
Figure 2.26. Pigments associated with the microphytobenthos at stations 613 
and 623. Data collected by H.L. Maclntyre. Pigments 
determined fluorometrically after extraction in acetone. 
Pigment data collected in this manner must be intrepeted 
cautiously. These figures show that benthic pigment can vary 
consistently between stations and that the amount of pigment 
in the upper 5 mm of sediment is similar in magnitude to the 
amount in the overlying water. 
69 
Figure 2.27. Photosynthetic performance of the microphytobenthos. 
Photosynthesis vs irradiance for two adjacent samples of 
sediment, 0-1 mm. Autotrophic potential is demonstrated. 
Similar results have been obtained for sections of sediment 
deeper than 5 mm. (Maclntyre, in prep). 
71 
Table 2.1 
-
LAVACA BAY 1984 1986 
vs Year 2
Comparison of Year 1 Nonparantetrie Hann-Whitney U Test (stations 1505and 1905excludedfromthisanalysis) 
1984 -1985  1985 -1986  
Median  Median  Significance  
Air Temperature (*C)  24.0  27.6  X X  
Water Temperature (*C)  24.0  25.5  ns  
Salinity (ppt)  2.50  9.13  « * II  
Secchi Depth (cm)  24.5  47.3  XXX  
pH  8.10  8.22  X  
Dissolved Oxygen (mg/l)  9.00  8.80  ns  
Ammonium (mg/l)  .004  .007  ,10>p>.05  
Nitrite (mg/l)  .001  .000  XXX  
Nitrate (mg/l)  .017  .001  XXX  
Phosphate (mg/l)  .035  .008  HUM  
Total Kjeldahl Nitrogen (mg/l)  .400  .585  M  
Total Phosphate mg/l)  .217  .115  XXX  
Chlorophyll  a (pg/l)  9.84  6.34  X X  
Pheopigment (pg/l)  4.60  2.68  * * *  

The symbols indicate the probablility level. No correction for multiple testing has been applied 
* <.05 
** <.01 **» <.001 
Table 2.2 
-
LAVACA BAY 1984 1986 
2-Way Analysis of Variance (nonparametric) 
By Months By Stations 
1984-85 1985-86 1984-85 1985-86 
1 
i 
*** *X 
*
Temperature; ns + 
j
1 

’* *•* ¥X X#r¥
SalinityI 
i 

• 
ns
Secchi Depth . 10>p>.05 X x ns 
pH 
* X nsns 
¥X XXX 
+
Dissolved Oxygen ns 
** X** 
—
Ammonium ns 
*** 
Nitrite ns ns ns 
'*¥.* X
Nitrate ns ns 
..
Phosphate . 10>p>.05 (+) +++ 
** * 
—
Total Kjeidah! Nitrogen .10>p>.05 ns 
+
ns ns
Total Phosphate X X 
ns +
Chiorophyli a . ;0>p>.05 
+
Pheopigment ns ns ns 
means the quantity is higher at the stations more affected by freshwater, means the quantity is lower at the stations more affected by freshwater. The number of symbols indicates the probability level, correcting for making two tests for each analysis 
X <.05 X X <.01 
XXX .001 
Table 2.3 74 
Lavaca Bay 
CONDUCTIVITY AND SALINITY 1984 1985

-
Measurements on the day of Nutrient Sampling 
Note;valuesfrom 1905and1505inAprilarequestionable. 
mmho/cm 
November January March April May June July August 
45 4.8 .6 2.5 6.1 .5 1.5 1.3 6.0 
603 5.8 / 1.2 1.1 t 2.0 2.7 9.0 
# 
65 6.5 1.8 1.2 1.1 1.5 A O 4.4 17.0
‘-t.U 
613 13.1 7.5 5.5 1.8 4.5 3.7 13.0 23.0 
623 14.9 20.0 8.4 2.8 2.8 10.0 14.0 23.0 
633 12.5 2.2 1.6 13.5 1 1.0 22.0 

85 12.5 21.5 10.0 3.6 6.8 16.0 15.0 26.0 
1505 21.9 30.5 
1905 10.9 31.7 

Salinity a gorithm; S (ppl)= a*(Cb) v/here C is conductivity 
(determined by log regression of conductivity 
a b vs salinity in laboratory calibration) 
Up to March 0.3708 1.129 
After March 0.4321 1.119 

Salinity ppt 
November January March April May June July August Average S.d. 
45 2.2 .2 1.0 3.5 .2 7 .6 5.2 1.42 1.28 
r­
603 2.7 .0 .5 .5 .3 1.5 0. 1 1.40 1.69 
65 3.1 .7 .5 .5 .7 2.5 2.3 10.3 2.55 3.29 
613 6.6 3.6 2.5 .8 2.5 1.9 7.6 14.4 5.02 4.48 523 7.9 10.9 4.1 1.4 1.4 5.7 8.3 14.4 6.75 4.57 533 6.4 1.0 .7 8.0 6.3 13.7 6.03 4.62 
1.8 3.7 9.6 8.9 16.6 7.98 4.78 
1505 13.7 19.8 
1905 6.5 20.7 

85 6.4 11.8 5.0 
Average 4.83 4.55 2.86 i .33 1.35 4.18 5.05 1 1.10 4.39 
2.46 5.45 .98 1.30 3.56 3.55 5.14 4.36
s.d. 2.37 
(note: stations 1505 and 1905 excluded from averages) 
-
Table 2.4 
Lavaca Bay 
HYDROGRAPHIC PARAMETERS 1984 1985


Temp.'C  
November  January  March  April  May  June  July  August  Average  s.d.  
45  14.9  6.8  15.2  24.8  26.3  26.5  32.3  31.3  22.22  9.00  
503  14.7  C C  16,1  24.8  27.0  27.0  70 A .V  31.0  no oa Z. .Z.  n oc y  
65  15.5  5.2  16.1  22.5  26.0  27.3  31.8  30.3  21.82  8.99  
613  16.3  6.0  17.8  24.3  26.5  27.5  30.5  30.5  22.39  8.48  
623  14.6  5.5  16.5  17.5  27.0  30.0  28.8  30.0  21.35  6.79  
633  17.0  21.0  25.6  28.0  28.3  28.5  24.75  4.73  
85  14.9  6.3  16.3  20.3  25.0  28.0  28.8  29.8  21.14  8.28  
1505  16.5  20.8  31.0  22.77  7.45  
1905  15.1  16.4  22.7  30.5  21.18  7.05  
Average  15.11  6.03  16.42  22.06  26.17  27.75  30.42  30.18  22.M  
S.d.  .61  .59  .72  2.41  .69  1.13  1.51  .91  7.84  
Dissolved Oxygen, mg/l  
November  January  March  April  May  June  July  August  Average  s.d.  
45  9.2  13.5  9.2  8.6  6.8  7.5  11.0  9.0  9.35  2.09  
603  9.1  14.4  9.8  10.4  7.2  8.5  11.0  9.0  9.93  2.15  
65  9.4  13.6  9.4  10.8  8.6  8.4  ! 0.6  7.4  9.78  1.91  
613  5.9  16.2  10.6  10.4  10.4  9.1  8.5  9.2  10.41  2.47  
623  9.0  16.6  13.0  8.4  7.8  8.1  7.5  8.2  9.83  3.25  
633  10.6  8.0  7.2  7.7  7.3  7.8  8.09  1.27  
85  9.2  15.8  9.1  9.2  8.0  7.2  6.5  7.7  9.09  2.89  
1505  8.2  8.4  6.3  7.63  1.16  
1905  10,2  8.5  8.5  6.1  8.33  1.69  
Average  9.29  15.02  9.82  9.19  8.00  8.06  8.31  8.33  9.37  
s.d.  .43  1.36  1.45  1.06  1.22  .66  2.05  .73  2.31  
* St 45 is 8/17  

Table ?.5 
Lavaca say HYDROGRAPHIC PARAMETERS 1984 1985
-
. 
pH  
November  January  March  April  May  June  July  August  Average  s.d.  
45  8.3  8.3  8.0  8.0  7.6  7.9  8.1  8.00  .23  
603  8.6  8.4  8.5  8.2  6.9  7.9  8.1  6.06  .56  
65  8.4  8.5  8.1  7.9  7.3  7.9  8.1  8.02  .37  
613  8.3  8.4  6.2  6.5  8.4  7.9  8.1  8.24  .19  
623  8.4  7.2  8.9  7.4  8.0  7.9  8.1  7.97  .56  
633  8.8  8.0  7.7  8.0  8.1  8.08  .41  
85  8.2  9.0  8.4  8.1  8.2  8.0  8.1  8.26  .35  
1505  7.9  6.4  7.5  7.93  .45  
1905  cdro  8.0  8.3  7.2  7.95  .52  
Average!  8.34  8.27  8.29  8.07  7.72  7.91  7.35  8.09  8.07  
c  1 A •* **  .59  .34  .32  .51  .02  o * .L 1  .02  .40  
Secchi Depth,  cm  
November  January  March  April  May  June  July  August  Average  s.d.  
45  60  20  23  23  19  36  17  34  29.0  14.3  
603  50  20  30  18  16  31  23  31  24.9  6.3  
65  41  20  18  18  25  42  31  35  28.8  9.9  
613  18  45  22  13  27  31  23  30  26.1  9.7  
623  52  50  39  15  16  13  24  28  29.6  15.6  
633  30  14  10  13  25  27  19.6  8.5  
85  45  90  36  13  27  16  47  47  40.1  24.2  
Average  41.0  40.8  28.3  16.3  20.0  26.0  27.1  53.1  28.6  
s.d.  15.2  27.6  7.7  3.6  6.5  11.9  9.7  6.8  14.4  

Table 2.6 
Lavaca Bay 
-
1984 1985
DISSOLVED AMMONIUM 
Replicate A mg/l  
Station November  January.  March  April  May  June  July  August  
45 .011  .075  .040  .002  .004  .004  .007  .003  
603 .007  .044  .009  .001  .003  .002  .004  .002  •  
65 .006  .085  .016  .001  .002  .002  .003  .004  
613  .012  .006  .000  .000  .000  .003  .002  
623  .006  .003  .000  .003  .022  .005  .003  
633  .003  .000  .014  .010  .004  .002  
85 .013  .007  .006  .001  .015  .052  .007  .021  
1505  .000  .001  .015  .019  .032  
1905 .004  .001  .014  .042  .050  .075  
Replicate B mg/l  
Station November  January  March  April  May  June  July  August  
45 .006  .075  .030  .000  .004  .012  .005  .001  
605 .013  .039  .013  .000  .002  .002  .002  .002  
65 .009  .085  .017  .000  .003  .001  .003  .001  
613 .009  .013  .007  .000  .000  .000  .002  .006  
623 .019  .005  .008  .000  .002  .015  .003  .003  
635  .002  .000  .004  .013  .003  .008  
85 .007  .005  .004  .001  .011  .042  .002  .003  
1505  
1905 .004  
Mean mg/l  
Station November  January  March  April  May  June  July  August  Average  s.d.  
45 .008  .074  .035  .001  .004  .008  .006  .002  .017  .024  
603 .010  .042  .011  .001  .002  .002  .003  .002  .009  .013  
65 .008  .084  .017  .000  .002  .001  .003  .002  .015  .028  
613 .009  .013  .006  .000  .000  .000  .002  .004  .004  .004  
623 .019  .006  .005  .000  .002  .019  .004  .003  .007  .00?  
633  .003  .000  .009  .011  .004  .005  .005  .005  
85 .010  .006  .005  .001  .012  .047  .004  .012  .012  .015  
1505  .000  .001  .015  .019  .032  .013  .013  
1905 .004  .001  .014  .042  .050  .075  .031  .029  
Average .010  .037  .012  .001  .005  .016  .010  .015  .011  
s.d. .005  .033  .011  .001  .005  .017  .012  .019  .017  
Mean pg­at/l  
Station November  January  March  April  May  June  July  August  Average  s.d.  
45 .59  5.26  2.47  .09  .28  .58  .41  46  1.23  1.75  
603 .72  2.96  .79  .04  .17  .12  .19  .14  .64  .96  
65 .55  6.01  1.18  .03  .16  .09  .19  .16  1.05  1.97  
613 .62  .90  .45  .02  .05  .00  .17  .29  .31  .32  
623 1.38  .42  .39  .01  .17  1.33  .27  .21  .52  .49  
633  .19  .02  .67  .81  ,25  .36  .38  .34  
85 .71  .42  .36  .10  .83  5.37  .31  .85  .87  1.05  
1505  .02  .09  1.06  1.38  2.26  .96  .94  
1905 .26  .04  .97  2.99  3.55  5.38  2.20  2.07  
Average .69  2.66  .83  .04  .38  1.15  .75  1.09  .75  
c ri 77  9 7R  7R  (\A  75  i 9n  R5  1 77  1 77  

Table 2.7 Lavaca Bay NITRITE 1984 -1905 
Replicate A mg/l  
Station November  January  March  April  May  June  July  August  
45 .000  .004  .005  .009  .012  .002  .004  .001  
603 .000  .006  .005  .005  .003  .001  .001  .001  .  
65 .000  .008  .006  .008  .002  .001  .000  .001  
613  .005  .004  .007  .000  .001  .001  .001  
623  ,007  .023  .006  .001  .002  .001  .001  
633  .007  ,012  .001  .001  .000  .001  
85 .001  .002  .011  .006  .001  .003  .000  .001  
1505  .015  .000  .001  .000  .000  
1905 .001  .010  .000  .000  .000  .000  
Replicate B mg/l  
Station November  January  March  April  May  June  July  August  
45 .000  .004  .006  .008  .012  .002  .004  .001  
603 .001  .006  .005  .005  .003  .001  .001  .001  
65 .000  .007  .005  .009  .002  .001  .000  .001  
613 .000  .005  .004  .005  .001  .001  .001  .001  
623 .001  .004  .035  .007  .001  .001  .001  .001  
633  .014  .008  .009  .001  .001  .000  .001  
85 .001  .001  .007  .007  .001  .003  .000  .000  
1505j  
1905 .000  
Mean mg/l  
Station November  January  March  April  May  June  July  August  Average  s.d.  
45 .000  .004  .006  .009  .012  .002  .004  .001  .005  .004  
603 .000  .006  .005  ,005  .003  .001  .001  .001  .003  .002  
65 .000  .007  .005  .008  .002  .001  .000  .001  .003  .003  
613 .000  .005  .004  .006  .000  .000  .001  .001  .002  .002  
623 .001  .005  .029  .006  .001  .002  .001  .001  .006  .010  
633  .007  .010  .001  .001  .000  .001  .004  .005  
85 .00!  .002  .009  .007  .001  .003  .000  .001  .003  .003  
1505  .015  .000  .001  .000  .000  .003  .007  
1905 .001  .010  .000  .000  .000  .000  .002  .004  
Average .001  .005  .009  .009  .002  .001  .001  .001  .004  
s.d. .001  .003  .009  .003  .004  .001  .001  .000  .005  
Mean pg­at/l  
Station November  January  March  April  May  June  July  August  Average  s.d.  
45 .00  .31  .40  .61  .85  .12  .27  .06  .33  .28  
603 .03  .41  .37  .37  .21  .08  .07  .06  .20  .16  
65 .01  .53  .39  .59  .12  .05  .02  .05  .22  .24  
613 .01  .37  .29  .44  .03  .00  .06  .04  .15  .17  
623 .10  .39  2.05  .45  .07  .12  .06  .04  .41  .70  
633  .53  .74  .08  .10  .02  .04  .25  .35  
85 .05  .11  .63  .48  .09  .22  .02  .04  .21  .23  
1505  1.08  .00  .06  .02  .02  .24  .47  
1905 .04  .71  .00  .02  .02  .02  .14  .26  
Average .04  .35  .66  .61  .16  .09  .06  .04  .26  
s fl .04  22  62  .19  .27  .06  .08  .02  .35  

Table 2.8  79  
Lavaca  Bay  
NITRATE  1984  1985  
Replicate A mg/l  
Station November  January - March  April  May  June  July  August  
45  .004  .487  .633  .458  .315  .002  .172  .001  
603  .003  .480  .490  .219  .139  .001  .001  .001  •  
65  .002  .584  .470  .316  .128  .002  .001  .002  
613  .341  .141  .118  .012  .000  .000  .003  
623  .063  .364  .296  .159  .015  .001  .000  
633  .235  .220  .568  .010  .000  .000  
85  .001  .059  .328  .324  .213  .064  .001  .000  
1505  .099  .006  .005  .002  .002  
1905  .000  .218  .006  .005  .002  .000  
Replicate  B mg/I  
Station  November  January  March  April  May  June  July  August  
45  .001  .493  .604  .462  .292  .038  .164  .001  
603  .001  .490  .514  .192  .145  .001  .001  .000  
65  .002  .577  .496  .331  .139  .006  .001  .002  
613  .002  .559  .129  .171  .010  .001  .000  .001  
623  .000  .033  .501  .316  .212  .014  .000  .000  
633  .245  .236  .441  .015  .001  .000  
65!  .001  .053  .266  .369  .265  .029  .000  .000  
1505  
1905  .001  
Mean  mg/l  
Station November  January  March  April  May  June  July  August  Average  s.d.  
45  .003  .490  .618  .460  .304  .020  .168  .001  .258  .237  
603  .002  .485  .502  .205  .142  .001  .001  .000  ,167  .208  
55  .002  .581  .483  .323  .133  .004  .001  .002  .191  .231  
613  .002  .350  .135  .145  .011  .000  .000  .002  .061  .124  
623  .000  .048  .433  .306  .185  .015  .001  .000  .123  .166  
633  .240  ,229  .505  .013  .001  .000  .164  .194  
85  .001  .056  .298  .346  .239  .046  .000  .000  .123  .142  
1505  .099  .006  .005  .002  .002  .023  .043  
1905  .000  .218  .006  .005  .002  .000  .039  .082  
Average  .001  .335  .387  .259  .170  .012  .019  .001  .148  
s.d.  .001  ,220  .165  .107  .160  .017  .057  .001  .188  
Mean pg­at/l  
Station  November  January  March  April  May  June  July  August  Average  s.d.  
45  .19  34.97  44.17  32.87  21.69  1.43  12.02  .10  18.43  16.96  
603  .13  34.61  35.86  14.67  10.12  .06  .06  .02  11.94  14.89  
65  .14  41.47  34.47  23.10  9.53  .28  .06  .16  13.65  16.50  
613  .14  24.98  9.65  10.35  .80  .00  .00  .14  5.75  8.84  
623  .02  3.45  30.91  21.89  13.23  1.05  .04  .00  8.82  11.88  
633  17.14  16.35  36.05  .90  .06  .00  11.75  13.85  
85  .08  4.00  21.27  24.73  17.08  3.30  .03  .00  8.81  10.16  
1505  7.11  .41  .35  .11  .13  1.62  3.07  
1905  .04  15.59  .46  .35  .11  .02  2.76  5.83  
Average|  .11  23.91  27.64  18.52  12.15  .86  1.39  .06  10.54  
<r fi 1  OR  1 c . 7/1  1 i  70  7 f, 1  1141  1  94  4 flQ  D7  13.43  

Table 2.9 
Lavaca Bay DISSOLVEDPHOSPHATE 
-
1984 1985 
Replicate A mg/l  
Station November  January  March  April  May  June  July  August  
45* .045  .177  .035  .071  .070  .038  .054  .015  
603 .022  .170  .027  .045  .045  .066  .017  .023  .  
65 .034  .182  .024  .043  .023  .052  .010  ,043  
613  .131  .008  .017  .005  .031  .015  .038  
623  .052  .003  .052  .028  .056  .01?  .035  
633  .007  .050  .053  .035  .015  .035  
85 .044  .034  .023  .052  .018  .038  .010  .040  
1505  .013  .000  .016  .010  .030  
1Q05  .003  .008  .016  .002  .025  
Replicate B mg/l  
Station November  January  March  April  May  June  July  Auaust  
45 .025  .200  .034  .073  .080  .040  .052  .015  
603 .026  .183  .024  .036  .043  .068  .015  .020  
65 .027  .193  .023  .034  .025  .026  .010  .043  
613 .046  .150  .010  .024  .005  .028  .012  .043  
623 .037  .040  .003  .041  .020  .061  .017  .013  
633  .010  .045  .048  .038  .020  .043  
85 .042  .016  .022  .052  .020  .042  .012  .103  
1505  
1905j  
Mean mg/l  
Station November  January  March  April  May  June  July  August  Average  s.d.  
45 .035  .189  .034  .072  A7C, .V < V  .039  .053  .015  .064  .053  
603 .024  .177  .026  .041  .044  .067  .016  .021  .052  .051  
65 .031  .187  .023  .038  .024  .039  .010  .043  .049  .055  
613 .046  .141  .009  .021  .005  .029  .014  .040  .038  .044  
623 .037  .046  .003  .046  .024  .059  .017  .024  .032  .019  
633  .008  .048  .050  .036  .017  .039  .033  .016  
85 .043  .026  .023  .052  .019  .040  .011  .071  .036  .023  
1505  .013  .000  .016  .010  .030  .014  .011  
1905  .003  .008  .016  .002  .025  .011  .010  
Average .036  .128  .018  .037  .028  .038  .017  .034  .041  
s.d. .009  .070  .011  .019  .024  .016  .014  .021  .041  
Mean pg­at/l  
Station November  January  March  April  May  June  My  August  Average  s.d.  
45 1.13  6.09  1.11  2.33  2.43  1.25  1.71  .48  2.07  1.70  
603 .78  5.70  .83  1.31  1.42  2.16  .52  .69  1.67  1.65  
65 .98  6.03  .75  1.24  .77  1.25  .32  1.37  1.59  1.78  
613 1.49  4.53  .29  .67  .16  .95  .44  1.29  1.23  1.42  
623 1.18  1.49  .09  1.50  .77  1.90  .56  .77  1.03  .62  
633  .26  1.54  1.62  1.18  .56  1.25  1.07  .53  
85 1.39  .84  .73  1.69  .61  1.29  .36  2.30  1.15  .73  
1505  .41  .00  .53  .32  .97  .44  .35  
1905  .11  .24  .53  .08  .81  .35  .31  
Average 1.16  4.11  .58  1.20  .89  1.23  .54  1.10  1.33  
s.d. .30  2.27  .36  .62  .77  .52  .46  .68  1.32  

Table 2.10 
Lavaca Bay TOTAL KJELDAHL NITROGEN 1984 1985
-
Replicate A mg/l  
Station  November  January.  March  "April  May  June  July  August  
45!  30  .12  .32  .37  .14  .25  .51  .34  
603  .28  .15  .10  .52  .10  .58  .62  .98  
65  .26  .17  .26  .u'9  .19  .46  .98  
613  .34  .20  .40  .67  .30  .72  .76  .54  
623  .12  .26  .42  7C .JyJ  .16  .94  .74  1.05  
633  .80  .71  .45  1.04  1.00  1.08  
85  .25  .90  .45  .41  .24  .77  .76  1.11  
1505  .31  .50  .67  .93  .77  
1905J  -12  .33  .18  .85  .76  1.13  
Replicate  B mg/l  
Station  November  January  March  April  May  June  July  August  
45  .22  .13  .26  .41  .20  .09  .65  
603  .24  .18  .15  .46  .10  .36  .73  .75  
65  .22  .18  .33  .63  .30  .36  .65  .35  
613  .29  .18  .36  .59  .20  .56  1.09  .60  
623  .18  .24  .54  .50  .29  .67  .85  .96  
633  .53  .75  .29  .73  .99  1.12  
85  '“**7  OO .UZ  .37  .45  .16  ,59  ,95  .98  
1505  
1905  
Mean  mg/l  
Station November  January  March  April  May  June  July  August  Average  s.d.  
45  .26  .13  .29  .39  .17  .17  .58  .34  .291  .155  
603  .26  .17  .13  .49  .10  .47  .66  .87  .394  .277  
65  .24  .18  .30  .76  .25  .41  .65  .67  .430  .257  
613  .32  .19  .38  .63  .25  .64  .93  .57  .488  .250  
623  .15  .25  .48  .43  .23  .81  .80  1.01  .517  .314  
633  .69  .73  .37  .89  1.00  1.10  .795  .263  
85  .24  ,86  .41  .43  .20  .73  .86  1.05  .596  .310  
1505  .31  .50  .67  .93  .77  .636  .240  
1905  .12  .33  .18  .85  .76  1.13  .562  .410  
Average  .226  .294  .368  .551  .249  .626  .796  .832  .500  
s.d.  .065  .268  .168  .161  .114  .254  .164  .275  .299  
Mean  pg­at/l  
Station  November  January  March  April  May  June  July  August  Average  s.d.  
45  18.6  8.9  20.7  27.9  12.1  12.1  41.4  24.3  20.76  11.04  
603  18.6  11.8  8.9  35.0  7.1  33.6  48.2  61.8  28.13  19.79  
65  17.1  12.5  21.1  54.3  17.5  29.3  46.4  47.5  30.71  18.39  
613  22.5  13.6  27.1  45.0  17.9  45.7  66.1  40.7  34.62  17.84  
623  10.7  17.9  34.3  30.4  16.1  57.5  56.8  71.8  36.92  22.39  
633  49.3  52.1  26.4  63.2  71.1  78.6  56.79  18.78  
85  17.1  61.4  29.3  30.7  14.3  52.1  61.1  74.6  42.59  22.16  
1505  22.1  35.7  47.9  66.4  55.0  45.43  17.14  
1905  8.6  23.6  12.9  60.7  54.3  80.7  40.12  29.27  
Average  16.17  21.01  26.27  39.34  17.78  44.68  56.87  59.44  35.74  
r* ri  /1 aa  10 n  1 1  OQ  1 1  SA  R  1S  1R  IS  11  79  IQ RS  71  37  

-
TOTAL PHOSPHATE 1984 1985 
Table 2.11 
Lavaca Bay 


Replicate A mg/l  
Station  November  January,  March  April  May  June  July  August  
45  .22  .36  .23  .30  .17  .37  .16  
603  .25  .35  .32  .28  .19  .28  .20  
65  .30  .24  .27  .14  .22  .16  
613  .21  .27  .32  .22  .14  .22  .17  
623  .28  .33  .31  .26  .24  .18  
633  .07  .33  .48  .29  .22  .19  
85  .11  .05  .31  .22  .21  .13  .13  
1505  .1 1  .07  .13  .09  .09  
1905  .05  ,08  .16  .08  .06  
Replicate B mg/l  
Station  November  January  March  April  May  June  July  August  
45  .20  .37  .27  .30  .22  .35  .16  
603  .24  .39  .29  .27  .20  .26  .21  
65  .36  .25  .26  .11  .20  .21  
613  O 1  .25  .33  .21  .17  .22  .18  
623  .19  .37  .26  .22  .25  .18  
633  .23  .31  .39  .26  .20  .19  
85  .20  .12  .30  .21  .22  .11  .11  
1505  
1905  
Mean  mg/l  
Station  November  January  March  April  May  June  July  August  Average  s.d.  
45  .21  .37  .25  .30  .19  .36  .16  .263  .079  
603  .24  .37  .31  .28  .20  .27  .20  .266  .059  
65  .33  .24  .26  .13  .21  .18  .226  .070  
613  .21  .26  .32  .22  .16  .22  .17  .222  .054  
623  .24  .35  .29  .24  .24  .18  .256  .060  
633  .15  .32  .43  .27  .21  .19  .264  .106  
85  .16  .09  .30  .21  .22  .12  .12  .174  .076  
1505  .11  .07  .13  .09  .09  .098  .024  
1905  .05  .08  .16  .08  .06  .086  .042  
Average |  .205  .217  .300  .237  .188  .200  .152  .224  
s.d.  .042  .122  .039  .100  .051  .082  .043  .086  
Mean  pg­at/l  
Station  November  January  March  April  May  June  July  August  Average  s.d.  
45  6.8  1 1.8  8.2  9.6  6.2  11.6  5.2  8.47  2.55  
603  7,8  11.9  9.9  9.0  6.3  8.6  6.6  8.59  1.91  
65  10.7  7.9  8.5  4.1  6.7  5.9  7.28  2.25  
613  6.8  8.4  10.4  7.0  5.0  7.0  5.6  7.17  1.73  
623  7.6  11.2  9.2  7.9  7.9  5.7  8.25  1.93  
633  4.8  10.5  14.0  8.7  6.8  6.3  8.50  3.43  
85  5.1  2.8  9.7  6.9  7.1  3.9  3.9  5.60  2.44  
1505  3.5  2.2  4.3  2.9  2.9  3.15  .79  
1905  1.6  2.6  5.1  2.6  2.0  2.76  1.35  
Average  6.60  7.01  9.66  7.65  6.06  6.44  4.90  7.21  
s d  1 36  3 Q.3  1 27  3 21  1 64  2.65  1.38  2.79  

Table 2.12 
Lavaca Bay CHLOROPHYLL a 1984 1985
-
Replicate  A pg/l  (Corrected algorithm)  
Station 45 603 65 613 623 633 85 1505 1905  November 21.0 9.7 12.4 9.9 7.7 3.8  January 3.1 .9 9.2 8.6 11.2 8.6  March 1.9 15.2 18.1 44.2 101.3 56.5 6.5  April 9.1 20.0 19.4 38.2 16.0 13.8 20.4 13.8 15.8  May 16.0  June 16.2 16.1 13.8 17.9 11.4 9.5 7.7 7.6 6.6  July 23.8 34.7 14.5 3.5 9.9 3.5 3.9 3.8  August 18.8 20.4 32.4 10.0 1.2 4.1 4.6 3.9 3.4  
Replicate B  pg/l  
Station 45 603 65 613 623 633 85  November 20.6 14.2 13.1 9.1 6.4  January 3.6 .9 9.1 8.1 18.4 15.5  March 2.1 14.6 18.2 46.7 94.5 35.3 7.3  April 10.6 1.2 23.1 34.3 8.4 15.2 23.8  May 17.8  June 16.6 15.6 15.9 18.4 10.2 7.9 8.0  July 23.1 41.9 15.7 17.6 4.1 9.8 4.5  August 17.4 18.3 31.1.­8.8 1.1 4.6 3.4  
Mean pg/1  
Station 45 603 65 613 623 633 85 1505 1905  November 20.8 11.9 12.8 9.5 7.0  January 3.3 .9 9.2 8.3 14.8 12,1  March 2.0 14.9 18.1 45.4 97.9 35.9 6.9  April 9.8 20.0 21.2 36.2 12.2 14.5 22.1 13.8 15.8  May 16.9  June 16.4 15.8 14.8 18.2 10.8 8.7 7.8 7.6 6.6  July 23.4 38.3 15.7 16.0 3.8 9.6 4.0 3.9 3.6  August 18.1 19.4 31.7 9.4 1.1 4.4 4.0 3.9 -3.4'  Average 15.42 17.32 17.66 20.45 23.44 14.66 10.1 1 7.29 7.42  s.d. 8.15 11.71 7.32 14.12 35.23 11.72 6.44 4.68 5.25  
Average s.d.  12.41 5.43  8.11 5.42  31.59 31.78  18.41 9.32  11.88 4.23  13.20 12.10  10.61 10.32  15.51  15.39  

Lavaca Bay PHEOPIGMEHTS 1984 1985

-
Table 2.13 84 

Replicate  A  pg/l  (Corrected algorithm)  
Station 45 503 55 615 623 633 85 1505 1905  November tj./ 7.5 6.6 8.4 6.0 1.3  January 5.7 5.8 7.4 2.7 3.3 2.5  March 2.7 10.2 8.6 12.8 11.7 8.7 3.1  April 5.9 10.5 10.2 13.0 1.6 6.9 7.8 3.6 4.7  May 7.1  June 7.6 3.6 5.6 4.0 11.8 12.1 10.6 3.3 2.7  July 11.3 11.4 5.6 5.6 3.9 3.3 1.9 .9 .7  August 5.7 6.0 14.6 3.8 1.6 2.6 2.3 .9 1.0  
Replicate B  pg/l  
Station November 45 5.7 603 9.8 65 7.3 613 8.5 523 633 85 5.7  January 5.0 5.2 9.0 2.7 2.6 2.9  March 2.9 10.5 7.5 9.7 13.1 8.0 2.7  April 5.3 7.1 10.9 12.3 1.0 7.8 8.5  May 6.6  June 6.7 4.3 5.1 3.6 ' 10.4 10.3 11.3  July 12.7 10.3 7.4 5.7 3.3 3.6 2.0  August 4.7 6.4 13.7 3.8 1.6 3.1 2.1  
Mean  pg/l  
Station November 45 5.7 603 8.6 65 7.0 613 6.5 623 633 85 5.8 1505 1905  January 5.3 5.5 6.2 2.7 2.9 2.7  March 2.8 10.3 8.0 11.3 12.4 8.4 2.9  April 5.6 8.8 10.5 12.6 1.3 7.4 8.1 3.6 4.7  May 6.8  June 7.1 3.9 5.4 3.8 11.1 11.2 10.9 3.3 2.7  July 12.0 10.9 6.5 5.6 3.6 5.4 2.0 .9 .7  August 5.2 6.2 14.1 3.8 1.6 2.8 2.2 .9 1.0  Average 6.25 7.76 8.54 6.90 5.49 6.65 5.19 2.19 2.27  S.d. 2.77 2.63 2.90 3.63 4.73 3.34 3.17 1.49 1.54  
Average s.d.  7.12 2.22  4.57 2.14  8.02 3.76  6.96 3.55  6.61 3.46  5.07 3.94  4.21 4.10  6.28  3.56  

-
Table 2.14 
Lavaca Bay 
PHYTOPLANKTON CELL COUNTS 1984 1985


Replicate A  cells/ml  •  
Station November 45 32524 603 14823 65 22876 613 15523 623! 14006 6j4 85 13352 1505| I905j  January 4305 9545 9181 9026 14395 15717  March 3968 28945 25936 52832 254455 24588 8501 13020  April 3968 28945 25936 52832 254435 24588 850! 13020  May o83 37270 54777 52754 56201 5356 20114 36360 34314  June 214717 726216 182851 610216 11230 88 /0 8384 10634  July 124883 212029 255731 206972 24536 15648 15095 12320 9643  August 173669 203237 56723 51043 28011 40772 78/5 16690 50316  
Replicate  B cells/ml  
Station 45 603 65 613 623 633 85 1505 1905  November 45985 23382 24471 14589 9921 20593  January 4694 6640 11230 18052 15772  March 5354 23913 24588 78898 194678 24691 13889  April 8429 63878 64693 -66604 56541 54703 32291  May 31201 22201 30454 46296 40616 18324 21205  June 54116 653465 319250 546216 17075 24834 12252  July 118270 251712 289700 50731 20619 j2/8-p 51746  August 123561 145347 66060 56334 27000 44974 8170  
Mean  cells/ml  
Station 45 605 65 613 623 633 85 1505 1905  November 39255 19102 23673 15056 11963 16973  January 4500 9545 7911 10128 14395 18052 14745  March 3661 26429 25262 65865 224556 24639 13889 8501 13020  April 6199 56411 45414 59718 155486 29645 32291 8501 13020  May 15792 29736 42616 49525 49409 1 1840 20658 38360 34314  June 134417 689841 251050 578217 14153 24834 10551 8384 10634  July 121576 231871 272716 128852 22578 24216 23420 12320 9843  August 148615 174292 61391 53686 27505 42873 8024 16690 50316  Average 59252 154653 91254 120l31 65006 25157 17569 15459 21858  S.d . 69365 228660 106572 184903 86209 11127 7744 11685 16683  
Average s.d.  21004 10081  1 1325 10081  45091 73604  45188 61317  32472 16816  191342 272574  94155 103799  64822 59868  74043  127737  

Table 2.15 Lavaca Bay 

PHYTOPLANKTON  BIOVOLUME  1984 - 1985  
Replicate A  pl/i  
Station 45 605 65 613 623 633 85 1505 1905  November 4.90 1.81 1.48 2.63 1.59 1.70  January 1.23 3.34 2.35 2.65 7.20 12.43  March .71 4.65 5.06 10.34 88.14 4.92 1.50 4.21  April 3.43 16.94 8.57 17.42 12.96 4.46 16.90 84.73 43.32  May .05 4.49 7.65 5.73 6.88 .58 2.03 4.83 7.19  June 12.42 35.94 9.64 38.69 1.72 1.85 4.32 12.12  July 15.55 18.01 23.10 12.33 2.18 1.94 4.16 .98 .72  August 21.32 17.02 4.98 3.86 2.92 2.93 .97 1.89 1.47  
Replicate B pl/l  
Station 45 603 55 613 623 633 85 1505 1905  November 11,00 3.31 1.91 2.84 .34 2.67  January 1.08 1.72 1.56 31.60 8.87  March .59 4.83 6.26 11.17 69.96 4.60 4.20  April 1.30 15.62 10.37 15.48 17.35 5.06 5.05  May 4.72 3.03 5.11 5.61 5.70 1.99 2.57  June 3.12 35.58 16.62 30.95 2.24 3.58 2.55  July 15.90 27.34 29.20 2.97 2.34 2.11 3.29  August 10.81 9.74 4.76 3.45 2.18 6.20 1.38  
Mean pl/l  
Station 45 603 65 613 623 OClU 85 1505 1905  November 7.95 2.56 1.69 2.74 1.22 2.18  January 1.16 3.34 2.04 2.10 7.20 31.60 10.65  March .65 4.74 5.66 10.76 79.05 4.76 4.20 1.50 4.21  April 2.36 16.28 9.47 16.45 15.15 4.76 10.97 84.73 43.32  May 2.39 3.76 6.38 5.67 6.29 1.29 2.30 4.83 7.19  June 7.77 34.76 13.13 34.82 1.98 3.58 2.20 4.32 12.12  July 15.73 22.68 26.15 7.65 2.26 2.03 3.74 .98 .72  August 16.07 13.38 4.87 3,65 2.55 4.56 1.18 1.89 1.47  Average 6.76 12.69 8.67 10.48 14.46 7.51 4.68 16.38 11.50  S.d. 6.75 11.49 7.93 10.80 26.65 8.28 4.56 33.52 16.13  
Average s.d.  3.06 2.72  8.30 2.72  12.84 26,49  22.61 20.47  4.45 2.31  12.74 13.84  9.10 10.06  5.51 5.91  9.80  14.61  

Table 2.16 
Lavaca Bay 
-
1985 1986 (Pratical Sanity from Hydrolab Conductivity) 
Salinity 
Replicate  A. ppt  
Station 45 603 65 613 623 633 85 1505 1905  October December February 4.7 o .U 5.3 9.9 1.1 8.7 6.9 1.4 8.7 15.9 4.9 15.6 19.6 8.1 10.6 15.2 8.0 6.2 20.8 8.0 13.1 26.9 16.8 14.4 29.1 20.4 18.0  April 13.4 17.1 17.1 20.8 24.2 23.2 23.9 27.7 28.4  June .5 7.5 1.0 16.4 20 1 19.1 19.1 26.7 26.7  Auqust 3.9 3.9 9.4 10.9 9.6 6.7 10.9 23,9 26.0  
Replicate B, ppt  
Station 45 603 65 613 623 633 85 1505 1905  October December February 4.1 Q 9.9 1.1 6.9 1.4 16.3 4.9 19.8 8.1 16.7 8.5 20.2 8.3 28.4 18.5 14 29.3 20.1 18  Aprii 13.4 17.4 15.1 21.1 24.2 23.2 23.9 28.1 26.4  June *7 . t 7.7 1.0 16.4 20.4 19.2 18.7 26.7 27.4  Auqust 3.9 3.9 9.4 10.9 9.9 9.0 11.2 24.6 26.3  
Mean, ppt  
Station 45 603 55 613 623 633 85 1505 1905  October December February 4.4 .9 5.3 9.9 1.1 8.7 6.9 1.4 8.7 16.1 4.9 13.6 19.7 8.1 10.6 16.0 8.3 6.2 20.5 8.2 13.1 28.7 18.7 14.4 29.2 20.3 18.2  April 13.4 17.2 16.1 20.9 24.2 23.2 23.9 27.9 28.4  June .6 7.6 1.0 16.4 20.3 19.1 18.9 26.7 27.0  Auqust 3.9 3.9 9.4 10.9 9.8 8.9 11.0 24.2 26.1  Average 4.51 7.37 6.52 12.67 14.55 13.09 14.84 23.41 24.87  s.d. 4.66 5.76 5.74 6.58 7.76 7.36 7.40 5.45 4.34  
Average s.d.  16.82 8.52  7.97 7.00  7.29 6.88  21.70 5.06  15.29 9.70  12.01 7.70  13.51  9.00  

Table 2.17 
Lavaca Bay 
-
WATER TEMPERATURE 1985 1986 
Replicate  A  *C  
Station 45 605 65 615 625 533 85 1505 1905  October December February 26.1 12.8 20.0 25.7 11.3 21.0 27.2 12.5 21.0 26.8 10.0 20.4 26.8 10.5 21.0 25.3 10.2 20.5 25.0 10.6 20.0 25.5 12.7 18.5 25.6 13.0 18.8  April 25.5 26.0 25.5 26.5 26.0 24.5 24.5 21.7 22.0  June 27.8 28.4 28.0 28.6 28.7 28.5 27.4 27.8 28.0  August 30.0 30.5 29.6 29.7 29.2 28.6 28.2 28.0 27.0  
Replicate B, "C  
Station 45 603 55 613 623 633 85 1505 1905  October December February 26.3 12.5 26.5 11.2 27.1 12.5 26.7 10.0 26.7 10.5 25.2 10.4 25.3 10.6 25.5 12.5 19.0 25.6 12.6 18.4  April 25.5 26.0 25.5 26.5 26.5 24.5 24.5 21.8 22.0  June 28.0 28.6 23.0 28.7 23.7 28.5 27.4 28.0 28.2  August 30.0 30.5 29.7 30.0 29.3 28.7 28.2 28.8 28.7  
Mean.  'C  
Station 45 603 65 513 623 633 85 1505 1905  October December February 26.2 12.7 20.0 26.1 11.3 21.0 27.2 12.5 21.0 26.8 10.0 20.4 26.8 10.5 21.0 25.3 10.3 20.5 25.2 10.6 20.0 25.5 12.6 18.8 25.6 12.8 18.5  April 25.5 26.0 25.5 26.5 26.3 24.5 24.5 21.8 22.0  June 27.9 28.5 28.0 28.7 28.7 28.6 27,4 27.9 28.1  August 30.0 30.5 29.7 29.9 29.3 28.7 28.2 28.4 27.9  Average 24.0 24.2 24.2 24.0 24.0 23.2 22.9 22.5 22.5  s.d. 6.2 6.9 6.3 7.4 7.1 6.0 6.5 5.8 5.7  
Average s.d.  26.1 .7  11.5 1.1  19.9 1.0  24.7 1.7  28.2 .4  29.2 .9  23.5  6.3  

Table 2.18 
Lavaca Bay 
-
SECCHI DEPTH 1985 1986 
Replicate  A. cm  
Station 45 603 65 613 V-D CN ro 533 85 1505 1905  October December February w 35 84 50 35 52 65 34 60 60 44 78 64 39 45 71 44 80 67 36 66 92 80 91  April 80 62 64 45 18 40 50 32 35  June 50 50 5! 45 62 66 60 50 47  August 50 34 46 42 26 19 34 45 43  
Replicate B.  cm  
Station 45 603 65 5)3 623 633 85 1505 1905  October December February 65 35 46 28 64 33 64 44 51 41 66 45 66 41 90  April 75 65 64 48 28 45 40 19 37  June 47 51 48 48 54 54 63  August 49 31 47 42 21 22 37 45 45  
Mean,  cm  
Station .b.CD 603! 65j 613 623 533 85 1505 1905  October December February cr> O' 36 84 48 32 52 65 34 60 52 44 76 58 40 45 69 45 80 67 39 66 91 80 91  April 78 54 64 47 23 43 45 26 36  June 49 51 50 47 58 60 62 50 47  August 50 33 47 42 24 1 36 45 44  Average 56.0 45.6 52.4 50.9 40.8 50.2 50.9 56.6 49.7  s.d. 17.1 12.3 11.9 i 5 .D 16.1 19.5 13.6 27.4 20.8  
Average s.d.  67.0 13.3  38.2 5.1  68.1 14.6  47.1 18.1  52.9 6.4  37.7 10.1  50.4  16.7  

Table 2.19 
Lavaca Bay pH 1985 -1986  
Replicate A  
Station 45 603 65 613 623 633 85 1505 1905  October December February 7.8 8.1 8.6 8,2 8.3 8.5 8.2 6.2 8.5 8.3 8.5 8.5 8.2 8.4 8.5 6.0 6.4 6.5 8.2 8.3 8.4 8.2 3.4 8.8 8.3 8.4 8.2  April 8.4 8.3 8.3 8.2 8.1 6.0 8.2 8.3 8.5  June 8.0 8.4 7.6 8.1 8.1 8.1 8.1 6.0 8.1  August 8.7 8.8 8.6 8.6 7.9 8.1 8.5  
Replicate 8  
Station 603 65 513 bzo 633 85 1505 1905  October December February 77 8.1 8.2 8.3 8.2 8.2 ¦’ 8.3 8.4 o.2 8.4 8.0 8.4 8.2 8.4 8.4 8.5 6.4 8.6  April 8.4 8.3 8.3 8.2 8.2 8.0 8.2 8.3 8.3  June 6.0 8.4 7.6 8.1 8.1 8.2 8.2 o.O 8.1  August 8.7 8.8 8.6 8.6 7.8 7.9 8.5  
Mean  
Station 45 603 65 613 623 633 85 1505 1905  October December February 7.8 8.1 8.6 8.2 8.3 8.5 8.2 8.2 8.5 8.3 8.4 8.5 8.2 8.4 8.3 8.0 8.4 8.5 8.2 8.4 8.4 8.2 8.4 8.6 8.3 8.4 8.4  April 8.4 8.3 8.3 8.2 8.1 8.0 8.2 8.3 8.3  June 8,0 8.4 7.6 8.1 8.1 8.1 8.1 8.0 8.1  August 8.7 8.8 8.6 8.6 7.9 8.0 8.5  Average 8.23 8.39 8.19 8.33 8.15 3.13 8.29 8.31 8.28  s.d. .35 .22 .34 .17 .19 .21 .13 .23 .18  
Average s.d.  8.13 .17  8.32 .11  8.48 .16  8,23 .12  8.05 .20  8.42 .35  8.25  .24  

Table 2.20 
Lavaca Bay DISSOLVED OXYGEN 1985 1986
-
Replicate  A. mg/l  
Station 45 603 65 613 623 633 85 1505 1905  October December February 9.7 9.9 9.5 10,2 10.5 9.7 12.0 10.2 9.8 10.6 11.1 7.5 8.7 11.1 9.0 8.4 11.2 9.2 8.3 11.5 8.8 7.6 10.7 9.0 7.7 10.5 8.8  April 9.5 9.1 6,9 9.2 9.0 8.3 8.2 8.3 8.0  June 8.2 8.4 8.2 10.3 7.4 7.3 7.8 7.8 7.9  August 7.4 8.7 8.0 8.7 7.1 7 6 7.5 7.5 6.7  
Replicate B. mg/l  
Station 45 603 63 613 623 633 85 1505 1905  October December February 9.5 9.8 10.2 10.7 12.2 10.2 10.4 11.2 10.2 ll.l 6.6 10.9 8.2 10.6 8.3 11.2 8.6 t t 10.4 0.6  April 9.5 8.5 3.6 8.9 8.9 8.1 8.7 8.2 8.1  June 8.2 8.8 5.5 10.4 7.5 7.5 7.9 7.6 7.4  August 7.7 8.8 7.7 8.7 7.3 7.4 7.5 7.5 6.7  
Mean, mg/l  
Station 45 603 65 613 623 653 65 1505 1905  October December 9.6 9.9 10.2 10.6 12.1 10.2 10.5 11.2 9.4 11.1 6.5 1 1.1 8.3 11.0 8.0 10.9 7.8 10.5  February 9.5 9.7 9.8 7.5 9.0 9.2 8.8 8.8 8.8  April 9.5 8.6 8.9 9.1 8,9 8.2 8.4 8.3 8.0  June 6.2 6.6 8.4 10.4 7.4 7.4 7.8 7.6 7.6  August 7.5 8.8 7.9 8.7 7.2 7.5 7.5 7.5 6.7  Average 8.98 9.41 9.50 9.73 8.83 8.59 8.61 8.54 8.23  s.d. .93 .86 1 .53 1.18 1.46 1.34 1.25 1.21 1.23  
Average s.d.  9.37 1.40  10.69 .47  8.98 .62  8.67 .49  8.17 .89  7.69 .66  8.93  1.28  

-
Table 2.21 Lavaca Bay DISSOLVED AMMONIUM 1985 1986

Replicate  A mg/1  
Station  October December February  April  June  August  
45  .001  .011  .012  .001  .041  .013  .  
603  .001  .006  .006  .001  .001  .030  
65  .000  .005  .006  .001  .029  .003  
613  .000  .007  .012  .003  .014  .008  
623  .001  .008  .008  .001  .014  .007  
633  .002  .006  .029  .02!  .004  .014  
85  .010  .024  .016  .005  .010  .025  
1505  - .006  .001  .021  .028  .012  ,041  
1905  .002  .002  .009  .011  .051  .013  
Replicate  B mg/I  
Station  October December February  April  June  August  
45  .001  008  .006  .000  .040  .004  
603  .007  .004  .005  .001  .012  .010  
65  .000  .005  .007  .001  .032  .015  
613  .000  .007  .011  .001  .014  .007  
623  .004  .007  .016  .003  .013  
633  .002  .003  .028  .014  .011  .008  
85  .004  .011  .008  .003  .010  .006  
1505  .003  .006  .019  .032  .005  .007  
1905  .004  .002  .011  .014  .047  .011  
Mean mg/i  
Station  October December  February  April  June  August  Average  s.d.  
45  .001  .009  .009  .001  .040  .009  .012  .014  
603  .004  .005  .006  .001  .007  .020  .007  .008  
65  .000  .005  .005  .001  .031  .009  .009  .0 ! 1  
613  .000  .007  .011  .002  .014  .003  .007  .005  
623  .002  .007  .012  .002  .014  .007  .007  .005  
635  .002  .004  .029  .018  .008  .011  .012  .010  
85  .007  .017  .012  .004  .010  .017  .011  .007  
1505  .005  .003  .020  .030  .009  .024  .015  .013  
1905  .003  .002  .010  .012  .039  .012  .013  .013  
Average  .003  .007  .013  .008  .019  .013  .010  
s.d.  .003  .005  .007  .010  .014  .010  .010  
Mean  pg-at/l  
Station  October December February  April  June  August  Average  s.d.  
45  .08  .66  .62  .04  2.89  .64  .82  1.02  
603  .27  .34  .46  .08  .47  1.45  .51  .59  
65  .01  .36  .44  .08  2.20  .64  .62  .79  
613  .01  .47  .81  .14  .99  .57  .50  .36  
623  .18  .53  .84  .14  .97  .50  .53  .37  
633  .13  .31  2.04  1.26  .54  .78  .84  .70  
85  .50  1.24  .84  .31  .73  1.21  .80  .51  
1505  .34  .25  1.42  2.14  .63  1.72  1.08  .92  
1905  .20  .17  .72  .89  2.78  .85  .93  .95  
Average  .19  .48  .91  .56  1.36  .95  .74  
s.d.  .20  .36  .53  .71  .99  .71  .73  

-
Table 2.22 Lavaca Bay DISSOLVED NITRITE 1985 1986

Replicate  A mg/l  
Station  October December February  April  June  August  
45  .003  .002  .000  .000  .004  .001  
603  .000  .002  .000  .000  .001  .001  
65  .000  .001  .000  .000  .004  .001  
613  .000  .001  .000  .000  .000  .000  
523  .000  .000  .000  .000  .000  .001  
653  .001  .000  .000  .002  .000  .001  
85  .000  .001  .001  .000  .000  .001  
1505  .000  .000  .001  .001  .001  .001  
1905  .000  .001  .000  .001  .001  .001  
Replicate  B mg/l  
Station  October December February  April  June  August  
45  '  003  .002  .000  .000  .003  .001  
603  .001  .002  .000  .000  .001  .001  
65  .000  .002  .000  .000  .004  .001  
613  .000  .000  .001  .000  .000  .000  
623  .000  .000  .000  .000  .000  .001  
633  .001  .000  .001  .001  .000  .001  
85  .000  .000  .000  .000  .000  .000  
1505  .000  .000  .000  .001  .000  .001  
1905  .000  .000  .001  .001  .002  .000  
Mean mg/l  
Station  October December February  April  June  August  Average  s.d.  
45  .003  .002  .000  .000  .003  .001  .002  .001  
603  .001  .002  .000  .000  .001  .001  .001  .001  
65  .000  .001  .000  .000  .004  .001  .001  .001  
613  .000  .001  .000  .000  .000  .000  .000  .000  
625  .000  ,000  .000  .000  .000  .001  .000  .000  
633  .00!  .000  .001  .002  .000  .001  .00!  .00!  
85  .000  .001  .001  .000  .000  .000  .000  .000  
1505  .000  .000  .000  .001  .000  .001  .000  .000  
1905  .000  .001  .001  .001  .002  .000  .001  .000  
Average  .001  .001  .000  .000  .001  .001  .001  
s.d.  001  .001  .000  .001  .002  .000  .001  
Mean pg-at/l  
Station  October December February  April  June  August  Average  s.d.  
45  .19  .17  .02  .02  .24  .05  .11  .10  
603  .04  .17  .00  .00  .06  .04  .05  .06  
65  .03  .09  .00  .02  .30  .04  .08  .11  
613  .03  .05  .03  .02  .02  .02  .03  .02  
623  .03  .02  .02  .02  .00  ,04  .02  .02  
633  .05  .00  .05  .13  .02  .04  .05  .05  
85  .01  .06  .10  .02  .00  .03  .03  .03  
1505  .01  .01  .03  .06  .03  .05  .03  .02  
1905  .03  .04  .04  .04  .11  .03  .05  .03  
Average  .05  .07  .02  .03  .09  .04  .05  
s.d.  ,06  .07  .03  .04  .11  .01  .06  

Table 2.23 Lavaca Bay DISSOLVED NITRATE 1985-1986 
Replicate A mg/I  
Station  October December February  April  June  August  
45  .172  .226  .001  .002  .136  .008  
503  .002  .157  .002  .000  .000  .002  
65  .001  .161  .000  .002  .127  .002  
613  .000  .052  .000  ,000  .000  .003  
623  .000  .028  .001  .000  .001  .001  
633  .063  .002  .005  .011  .001  .002  
85  .000  .063  .003  .003  .001  .000  
1505  .000  .005  .003  .010  .002  .001  
1905  .000  .019  .001  .009  .003  .003  
Replicate 5  mg/I  
Station  October December February  April  June  August  
45  .172  .222  .003  .000  .143  .001  
603  .001  .162  .001  .000  .001  .020  
65  .000  .151  .001  .006  122  .000  
613  .000  .043  .001  .001  .001  .001  
623  .001  .039  .001  .001  .000  .001  
633|  .071  .000  .006  .011  .000  .002  
65  .000  .037  .002  .005  .001  .001  
1505j  .000  .018  .003  .011  .001  .00i  
1905  .001  .016  .002  .009  .004  .001  
...  
Moan  mg/I  
Station  October December February  April  June  August  Average  s.d.  
45  .172  .224  .002  .001  .139  .004  .090  .096  
603  .001  .159  .001  .000  .001  Oil  .029  .061  
65  .001  .156  .001  .004  .124  .001  .048  .069  
513  .000  .048  .001  .001  .001  .002  .009  .018  
623  .000  .034  .001  .000  ’  .001  .001  .006  .013  
633  .067  .001  .005  .011  .000  .002  .015  .025  
85  .000  .050  .005  .004  .001  .001  .010  .020  
1505  .000  .01 1  .003  .010  .001  .001  .005  .005  
1905  .000  .017  .002  .009  .004  .002  .006  .006  
Average  .027  .076  .002  .004  .030  .003  .024  
s.d.  .057  .078  .002  .004  .056  .005  .052  
Mean  p§ -at/l  
Station  October December February  April  June  August  Average  s.d.  
45  12.25  16.01  .15  .05  9.96  .31  6.46  6.82  
603  .09  1 1.39  .09  .00  .05  .76  2.06  4.37  
65  .04  11.13  .08  .29  8.89  .07  3.41  4.92  
613  .02  3.41  .05  .04  .05  .13  .62  1.31  
623  .03  2.39  .06  .03  .04  .05  .43  .93  
633  4.77  .09  .39  .78  .03  .16  1.04  1.77  
85  .02  3.56  .19  .27  .04  .06  .69  1.40  
1505  .02  .81  .23  .73  .11  .08  .33  .39  
1905  .03  1.23  .13  .61  .25  .12  .40  .44  
Average  1.92  5.56  .15  .31  2.15  .19  1.71  
s.d.  4.06  5.59  .12  .31  4.01  .32  3.72  

Table 2.24 
Lavaca Bay 
DISSOLVED PHOSPHATE 1985-1986 

Replicate A mg/l  
Station  October December February  April  June  August  
45  .007  .064  .030  .014  .065  .014  
,  
603  .002  .053  .013  .007  .027  .007  
65  .004  .038  .013  .012  .075  .012  
613  .001  .013  .009  .002  .015  .002  
623  .002  .018  .004  .007  .005  .007  
633  .003  .005  .013  .007  .010  .007  
85  .003  .020  .009  .005  .007  .005  
1505  .003  .000  .011  .005  .002  .005  
1905  .002  .008  .009  .002  .005  .002  
Replicate 5  mg/l  
Station  October December  February  April  June  August  
45  .007  .064  .025  .014  .062  .014  
603  .002  .048  .035  .009  .032  .009  
65  .003  .046  .016  .012  .070  .012  
613  .002  .013  .009  .005  .010  .005  
623  .002  .015  .004  .005  .005  .005  
633  .003  .010  .009  .007  .005  .007  
65  .002  .015  .006  .005  .010  .005  
1505  .003  .003  .009  .002  .002  .002  
1905  .002  .008  .002  .005  .002  .005  
Moan mg/l  
Station  October December February  April  June  August  Average  s.d.  
45  .007  .064  .028  .014  .064  .014  .032  .024  
603  .002  .051  .024  .008  .030  .008  .021  .018  
65  .003  .042  .015  .012  .072  .012  .025  .025  
613  .001  .013  .009  .004  .012  .004  .007  .005  
623  .002  .017  .004  .006  .005  .006  .006  .005  
633  .003  .008  .011  .007  .007  .007  .007  .003  
S5  .003  .018  .008  .005  .009  .005  .008  .005  
1505  .003  .003  .010  .004  .002  .004  .004  .003  
1905  .002  .008  .005  .004  .004  .004  .004  .003  
Average  .003  .024  .012  .007  .023  .007  .013  
S.d.  .002  .021  .009  .004  .026  .004  .016  
Mean  pg -at/l  
Station  October December February  April  June  August  Average  s.d.  
45  .23  2.05  .89  .46  2.05  .46  1.02  .79  
603  .08  1.64  .78  .27  .97  .27  .67  .56  
65  .11  1.35  .47  .38  2.33  .38  .84  .81  
613  .04  .41  .28  .11  .40  .11  .23  .16  
623  .05  .53  .13  .19  .16  .19  .2!  .16  
633  .10  .25  .36  .23  .24  .23  .23  .10  
85  .08  .57  .24  .15  .28  .15  .25  .17  
1505  .09  .08  .32  .11  .08  .11  .13  ,10  
1905  .07  .25  .17  .11  .12  .11  .14  .08  
Average  .10  .79  .40  .22  .74  ,22  .41  
s.d.  .05  .69  .29  .12  .84  .12  .53  

-
Table 2.25 Lavaca Bay TOTAL KJELDAHL NITROGEN 1985 1986

Replicate A mg/l  
Station  October  December February  April  June  August  
45  .26  .17  .55  .90  .40  .67  
603  .67  .22  .36  .44  1.01  
65  .25  .16  .30  1.33  .60  .49  
613  .65  .30  .69  .85  .58  
623  1.09  .17  1.17  .78  .60  
653  .27  .26  .50  .77  .75  .72  
85  .54  .12  .71  .91  .74  .64  
1505  .76  .1 1  .77  .67  .44  .45  
1905  .51  .44  .73  1.05  .42  .52  
Replicate  B mg/l  
Station  October  December February  April  June  August  
45  .27  .03  .54  .92  .53  .74  
603  .78  .09  O 1  .31  .94  
65  .15  .14  .21  1.20  .72  .56  
613  .52  .18  .90  .68  .55  
623  .31  .04  1.46  .84  .62  
633  .53  .33  .82  .77  .70  
65  .87  .22  .65  .84  .30  .62  
1505  .62  .10  
c*oin  uoCO  .29  .63  
Mean mg/l  
Station  October  December February  April  June  August  Average  s.d.  
45  .27  .10  .55  .91  .37  .71  .482  .286  
603  .73  .15  .84  .38  .98  .613  .324  
65  .20  .15  .26  1.27  .76  .53  .526  .412  
613  .59  .24  .80  .77  .57  .590  
625  .95  .11  1.32  .81  .6!  .758  .453  
655  .40  .50  .25  .60  .76  .71  .584  .215  
85  71  .17  .68  .88  .77  .63  .638  .246  
1505  .69  .11  .39  .34  O'*# .ZZ  07  .490  .268  
1905  .55  .37  .68  .53  .21  .26  .574  .219  
Average  .563  .187  .559  .956  .629  .651  .584  
s.d.  .252  .106  .183  .226  ,199  .150  .301  
Mean  pg -at/1  
Station  October December February  April  June  August  Average  s.d.  
45  18.93  7.14  38.93  65.00  26.07  50.36  34.40  20.46  
603  51.79  11.07  59.64  26.79  69.64  43.79  23.15  
65  14.29  10.71  18.21  90.36  54.29  37.50  37.56  29.43  
613  41.79  17.14  56.79  54.64  40.36  42.14  15.87  
623  67.86  7.50  93.93  57.86  43.57  54.14  30.93  
633  28.57  21.07  17.86  56.79  54.29  50.71  41.69  15.36  
85  50.36  12.14  48.57  62.50  55.00  45.00  45.60  17.54  
1505  49.29  7.50  27.50  23.93  15.71  16.07  35.00  19.11  
1905  38.93  26.07  48.57  37.50  15.00  18.57  41.03  15.64  
Average]  40.20  13.37  39.93  68.30  44.96  46.47  41.69  
s.d.  16.00  7.60  13.10  16.16  14.18  10.75  21.52  

Table2.26 
Lavaca Bay 
-
1986
TOTAL PHOSPHATE 1985 
Replicate A mg/i  
Station October December February  April  June  August  
45 .15 .24 .10  ,12  .12  .12  
603 .14 .26 .11  .13  .11  .13  
65 .13 .23 .06  .11  .14  .11  
613 .10 .16 .08  .1 1  09  11  
623 .13 .11 .12  .24  .07  .24  
633 .10 .13 .07  .17  .06  .17  
85 .09 .18 .07  .17  .07  .17  
1505 .10 .07 .07  .18  .11  .18  
1905 .09 .11 .10  22  .10  .22  
Replicate 5 mg/l  
Station October December February  April  June  August  
“451 .18 .25 .10  .11  .12  .11  
603 .13 .30 .12  .14  .11  .14  
65 .16 .27 .10  .1 1  .15  .11  
613 .10 .15 .09  .1 1  .08  .1 1  
623 .12 .13 .14  .26  .07  .26  
633 .10 . 13 .05  .18  .05  .18  
85 .12 .18 .06  .14  .07  .14  
1505 .10 .06 .06  .28  .08  .28  
1905 .10 .10 .10  ...26  .12  .26  
Mean mg/i  
Station October December February  April  June  August  Average  s.d.  
45 .16 .24 .10  .11  .12  .11  .143  .052  
603 .14 .28 .11  .14  .11  .14  .151  .061  
65 .14 .25 .08  .11  .13  .11  .138  .058  
613 .10 .16 .08  < « . ( 1  .09  .11  .108  .026  
623 .13 .12 .13  .25  .07  .25  .158  .071  
633 .10 .13 .06  .17  .05  .17  .116  .05!  
85 .10 .16 .07  .15  .07  .15  .120  .047  
1505 .10 .06 .07  .23  .10  .23  .132  .081  
1905 .10 .11 .10  .24  .11  .24  .151  .069  
Average .119 .170 .090  .169  .095  .169  .135  
s.d. .025 .071 .024  .060  .028  .060  .059  
Mean jig-at/l  
Station October December February  April  June  August  Average  s.d.  
45 5.25 7.84 3.22  3.69  4.00  3.69  4.62  1.67  
603 4.36 8.92 3.67  4.38  3.50  4.38  4.87  1.96  
65 4.56 8.06 2.70  3.51  4.33  3.51  4.44  1.86  
613 3.26 5.07 2.72  3.55  2.77  3.55  3.49  .84  
623 4.05 3.95 4.13  8.05  2.26  8.05  5.08  2.30  
633 3.24 4.31 1.98  5.64  1.73  5.64  3.76  1.65  
85 3.31 5.76 2.14  4.93  2.17  4.93  3.88  1.53  
1505 3.31 2.08 2.14  7.39  3.13  7.39  4.24  2.60  
1905 3.19 3.46 3.28  7.83  3.61  7.83  4.87  2.24  
Average 3.84 5.50 2.89  5.44  3.06  5.44  4.36  
s.d. .79 2.30 .77  1.94  .90  1.94  1.91  

Table 2.27 
Lavaca Bay 
-
1985 1986
CHLOROPHYLL a 
Replicate  A  pg/l  (corrected algorithm)  
Station  October December  February  April  June  August  
45  24.88  8.99  14.04  7.11  4.69  21.66  
603  15.85  14.67  7.92  5.57  11.20  29.18  
65  14.95  14.52  9.72  8.45  4.90  13.23  
513  16.00  12.22  5.97  7.56  11.50  9.85  
623  5.31  4.20  28.87  14.15  3.98  5.54  
633  5.02  2.39  4.44  5.32  1.49  10.08  
85  10.42  5.80  1.96  11.03  1.80  6.77  
1505  10.77  5.91  2.88  12.98  9.57  9.06  
1905  6.14  7.67  6,29  12.14  9.49  10.56  
Replicate B  pg/l  
Station  October December February  April  June  August  
45  16.27  11.40  11.55  7.59  4.49  73 R4  
603  18.33  19.30  7.33  6.24  12.75  28.25  
65  IU. *  16.76  8,85  9.45  4 03  12.79  
613  13.36  12-.24  8.74  7.25  16.32  10.59  
623  7.94  6.88  24.90  13.41  4.23  6.85  
633  5.09  2.59  2.48  6.98  1.56  10.23  
65  2.16  11.28  1.55  9.44  
1505  8.06  6.52  4.85  11.52  10.61  9.03  
1905  8.91  7.52  6.59  12.35  9.14  1 1.10  
Mean  pg/l  
Station  October December February  April  June  August  Average  s.d.  
45  20.57  10.20  12.79  7.35  4.59  22.75  13.04  7.21  
603  17.09  16.99  7.63  5.91  11.97  28.71  14.72  7.98  
65  15.56  15.64  9.28  8,95  4.46  13.01  11.15  4.23  
513  14.68  12.23  7.35  7.41  13.91  10.27  10.97  3.30  
623  6.63  5.54  26.88  13.78  4.10  6.19  10.52  8.38  
633  5.05  2.49  3.46  6.15  1.53  10.15  4.81  3.02  
65  10.42  5.60  2.06  11.16  1.67  8.10  6.22  4.13  
1505  9.42  6.21  3.87  12.25  10.09  9.05  8.48  2.96  
1905  8.52  7.59  6.44  12.25  9.32  10.74  9.14  2.03  
Average  12.09  9,39  8.86  9.47  6.85  13.22  9.96  
s.d.  5.50  4.97  7.36  2.90  4.51  7.29  5.91  

Table 2.28 
Lavaca Bay PHEOPIGMEHT 1985 
-
1986 
Replicate  A pg/l  (corrected algorithm)  
Station  October December February  April  June  August  
45  3.12  3.87  3.94  1.81  3.48  4.65  
603  4.18  5.19  3.34  2.17  4.09  4.92  
65  3.65  4.03  2.98  2.60  2.99  5.02  
613  3.31  3.23  3.38  3.60  4.97  3.05  
623  3.08  2.92  7.29  6.52  2.48  4.58  
633  2.23  3.04  3.52  2.99  2.55  6.09  
85  2.18  2.12  2.51  3.67  2.46  3.56  
1505  2.77  2.49  3.58  3.22  3.47  2.57  
1905  2.66  3.88  4.15  3.45  3.28  2.69  
Replicate  B pg/i  
Station  October December February  April  June  August  
45  3.12  3.87  3.94  1.81  3.48  4.65  
605  4.16  5.19  3.34  2.17  4.09  4.92  
65  5.65  4.03  2.98  2.60  2.99  3.02  
613  3.31  3.25  3.38  3.80  - 4.97  3.03  
623  3.08  2.92  7.29  6.52  2.48  4.53  
633  2.23  3.04  3.32  2.99  2.55  6.09  
85  2.18  2.12  2.51  3.67  2.46  3.56  
1505  2.77  2.49  3.56  3.22  3.47  2.57  
1905  2.66  3.68  4.15  3.45  3.28  2.69  
Mean  pg/l  
Station  October December February  April  June  August  Average  s.d.  
45  3.12  3.87  3.94  1.81  3.48  4.65  3.48  .92  
603  4.16  5.19  3.34  2.17  4.09  4.92  3.98  1.05  
65  3,65  4.03  2.96  2.60  2.99  3.02  3.21  CA •JO  
613  3.31  3.23  3.38  3.80  4.97  3.03  3.62  .68  
623  3.08  2.92  7.29  6.52  2.46  4.58  4.48  1.93  
633  2.23  3.04  3.32  2.99  2.55  6.09  3.37  1.32  
85  2.18  2.12  2.51  3.67  2.46  3.56  2.75  .65  
1505  2.77  2.49  3.58  3.22  3.47  2.57  3.02  .45  
1905  2.66  3.88  4.15  5.45  3.28  2.69  3.35  .58  
Average  3.02  3.42  3.83  3.36  3.31  3.90  3.47  
S.d.  .63  .90  1.34  1.32  .81  1.17  1.08  

Table 2,29 
Lavaca Bay 
PHYTOPLANKTON 1985-1986 

(Note thatUnits for Cell Numbers are Cells/pl) 
Phytoplankton  Cell Numbers, cells/pl  
Station  October December February  April  June  August  Average  s.d.  
45  580  510  1240  1280  1490  1210  1052  405  
603  247  569  2380  654  3710  2450  1668  1382  
65  1230  901  3020  624  1350  9800  2821  3520  
613  762  1500  1130  656  948  7730  2121  2764  
623  757  611  1390  1040  606  11900  2717  4509  
633  289  1190  663  191  1970  9350  2276  3527  
85  590  881  933  420  641  13700  2861  5313  
1505  128  246  448  285  477  6080  1277  2356  
1905  124  309  213  745  825  5610  1304  2129  
Average  523  746  1269  655  1335  7537  2011  
s.d.  365  411  909  346  1014  4141  3041  
Phytoplankton  Biovolume, pl/l  
Station  October December February  April  June  August  Average  s.d.  
45  7.9  11.1  26.5  4.2  12.9  6.1  11.4  8.0  
603  20.1  4.4  18.9  1.7  10.6  7.9  10.6  7.6  
65  94.9  6.8  52.2  1.9  1.5  53.5  35.1  38.1  
613  20.1  11.6  3.0  1.2  1.5  20.0  9.6  9.0  
623  16.0  3.9  6.0  3.3  2.1  32.3  10.6  11.8  
633  12.4  14.0  3.0  0.6  6.9  24.6  10.2  8.7  
85  16.3  15.9  1.6  1.7  1.4  30.6  11.3  11.8  
1505  40.5  2.8  11.2  1.8  4.2  15.5  12.6  14.6  
1905  4.5  20.1  3.9  2.5  3.0  19.1  8.8  8.4  
Average  25.8  10.1  14.1  2.1  4.9  23.3  13.4  
s.d.  27.8  6.0  16.6  1.1  4.3  14.5  16.7  

1985-1906 (all stations combined) 
Table 2.30 Lavaca Bay PHYTOPLANKTON TAXONOTHC COHPOSITION 

Relative fraction of total concentration (cells/ ml)  
Taxon  October  December February  April  June  August  Average  
Cyanophytes  .826  .733  .828  .850  .911  .919  .844  
Diatoms  .006  .003  .009  .001  .001  .000  .003  
Chlorophyles  .121  .197  .140  .125  .080  .070  .122  
Cryptophyles  .003  .002  .001  .001  .000  .000  .001  
Dinoflagellales  .001  .000  .000  .000  .000  .000  .000  
Flagellates & Monads  .043  .064  .021  .023  .008  .010  .028  
Monthly relative fraction:  .127  .175  .256  .217  .035  .191  1.00  
«  
Relative fraction of total biovolume (|il/ml)  
Taxon  October  December February  April  June  August  Average  
Cyanophytes  .666  .530  .942  .529  .605  .700  .662  
Diatoms  .106  .199  .021  .098  .168  .030  .104  
Chlorophytes  .034  .094  .011  .087  .062  .051  .057  
Cryptophytes  .003  .014  .002  .017  .010  .005  .009  
Dinoflagellales  .159  .017  .014  .122  .059  .009  .063  
Flagellates & Monads  .033  .143  .009  .146  .092  .201  .104  
Monthly relative fraction:  .208  .077  .454  .031  .031  .200  1.00  

Table 2.31 
John Cullen Light-Limitation 
Model 

(photosynthesis Model from Platt et aL 1980. J. Mar. Res. 38; 687-701) 
-
Model of photosynthesis: Pi = Ps*(l exp((-a*l)/Ps))*exp((-b*l)/Ps) Definition of saturating light: Is Ps/a
= 
=
Scaling of photosynthesis; P' Pi/Ps 
= 
1/ls
Scaling of light; 1' Scalingofattenuationcoefficient:k' k/z wherezisdepthofthewell-mixedlayer
= 
=­
Scaled Photosynthesis equation: P' (1 exp(-l'))*exp((-b*r)/a) 
6 April 1986 1200h 
water column avg. Ps 23.95 
from MA thesis .072

alpha 
of R.F. Davis: beta .0034 Is 333 pmol/rrT2/s lo 586 
(cloudy) 
k 2.4 rrT-1 water depth 1.7 m k' 1.41 
P 1.76 
Table of relative photosynthesis in a mixed layer as afunctionofincidentlightandwaterclarity 
Across: Extinction coefficient k\ 
=
(water column depth IX light depth when k' = 4.61) Down: I' lo/ls (Incident light/Saturating light)
= 
Correcting for Respiration. Relative to Reference Rate from Sampling Date 
k' --> 
r .5 1.0 1.5 2.0 4.0 6.0 10.0 20.0 40.0 
.5 .55 .41 .30 .22 .02 -.07 -.14 -.19 -.22 
1.0 1.07 .87 .71 .57 .23 .08 -.05 -.15 -.20 
1.5 
1.39 1.19 1.00 .83 .39 .19 .01 -.12 -.18 

2.0 
1.60 1.41 1.21 .53


1.03 .28 .07 -.09 -.17 
4.0 1.82 1.76 1.63 1.47 .86 .52 .21 -.02 -.14 
8.0 1.62 1.71 1.73 1.68 1.15 .73 .34 .04 -.11 
10.0 1.49 1.62 1.69 1.68 1.22 .79 .38 .06 -.10 
15.0 1.20 1.38 1.51 1.58 1.31 .88 .44 .09 -.09 
20.0 .96 1.16 1.33 1.45 1.34 .93 .47 .10 -.08 
The outlined cell represents the approximate conditions midday on the day of sampling. 
Water column photosynthesis is clearly sensitive to incident light and water clarity. 
LVDLigntrameAproo 
Table 2„31 (cent.) 
Light-limitation Model  
Lavaca Bay April 1985  
Correcting for Respiration  = Pmax*  .1  
k'  —>  
1'  .5  1.0  1.5  2.0  4.0  6.0  10.0  20.0  40.0  
.5  .22  .16  .12  .09  .01  -.03  -.06  -.08  -.09  
1.0  .42  .35  .28  .22  .09  .03  -.02  -.06  -.08  
1.5  .55  .47  .40  .33  .16  .07  .01  -.05  -.07  
2.0  .63  .56  .48  .41  2\  .11  .03  -.04  -.07  
4.0  .72  .70  .65  .58  -34  .20  .08  -.01  -.06  
...  
8.0  .64  .68  .69  .66  .45  .29  .14  .02  -.04  
10.0  .59  .64  .67  .66  .48  .31  .15  .02  -.04  
15.0  .47  .54  .60  .63  .52  .35  .17  .04  -.03  
20.0  .38  .46  .52  .57  .53  .37  .18  .04  -.03  
Relative Rate of Gross Photosynthesis  -Maximum =  1.0  
0.5  1  1.5  2  4  6  10  20  40  
0.5  .32  .26  .22  .19  .11  .07  .04  .02  .01  
1  .52  .45  .38  .32  .19  .13  .08  .04  .02  
1.5  .65  .57  .50  .43  .26  .17  .11  .05  .03  
2  .73  .66  .58  .51  .31  .21  .13  .06  .03  
4  .82  .80  .75  .65  .44  .30  .18  .09  .04  
8  .74  .78  .79  .76  .55  .39  .24  .12  .06  
10  .69  .74  .77  .76  .58  .41  .25  .12  .06  
15  .57  .64  .70  .73  .62  .45  .27  .14  .07  
20  .48  .56  .62  .67  .63  .47  .28  .14  .07  

/ 
LVBLightT ableApr86 
Table 2.32 
John Cullen Light-Limitation Model 2/24/87 (photosynthesis ModelfromPlattetal. 1980.J.Mar.Res.38;687-701) 
-
Model of photosynthesis; Pi = Ps*(l exp((-a“l)/Ps))*exp((-b*l)/Ps) 
Definition of saturating light; Is = Ps/a 
Scaling of photosynthesis; P' = Pi/Ps 

=
Scaling of light; I' l/ls Scalingofattenuationcoefficient;k' =k/z wherezisdepthofthewell-mixedlayer 
-
=
Scaled Photosynthesis equation: P' (1 exp(-f))*exp((-b*r)/a) 
4 June 1986 1200 h 
water column Ps 12.72
avg. from MA thesis alpha .059 of R.F. Davis: beta .0013 Is 216 pmol/rrf2/s lo 1768 pmol/fTT2/s (cloudy) k 2.0 rrT-1 water depth 1.7 m k' 1.18 P 8.20 
Table of relative photosynthesis in a mixed layer as a functionofincidentlightandwaterclarity 
Across: Extinction coefficient k'. 
=
(water column depth 1% light depth when k' = 4.61) Down: I' = io/ls (Incident light/Saturating light) 
Correcting for Respiration. Relative to Reference Rale from Sampling Date 
—
V> 
r .5 1.0 1.5 2.0 4.0 6.0 10.0 20.0 40.0 
.5  .28  .21  .16  .11  .01  -.03  -.07  -.10  -.11  
1.0  .55  .45  .36  .29  .12  .04  -.03  -.08  -.10  
2.0  .84  .74  .64  .54  .27  .15  .04  -.04  -.08  
4.0  1.01  .96  .88  .79  .46  .28  .12  -.01  -.07  
6.0  1.01  1.00  .96  .89  .56  .35  .16  .02  -.06  

8.0 .98 1.00 .99 .94 .63 .40 .19 .03 -.05 
10.0  .95  .98  .99  .96  .68  .44  .22  .04  -.04  
15.0  .86  .91  .95  .96  .75  .50  .26  .06  -.03  
20.0  .78  .84  .89  .92  .79  .54  .28  .08  -.03  
The outlined cell represents the approximate conditions  
midday on the day of sampling.  
Watercolumn photosynthesis is near maximal for the  
likely range of incidentlight and waterclarity  
LVBLighlTableJun86  2/24/87  

Light-Limitation Model 
Tab!e 2.32 (Cont.) 

Correcting for Respiration  = Pmax*  .1  
k'  —>  
r  .5  1.0  1.5  2.0  4.0  6.0  10.0  20.0  40.0  
.5  .22  .17  .12  .09  .01  -.03  -.06  -.08  -.09  
1.0  .43  .35  .29  .23  .09  .03  -.02  -.06  -.08  
2.0  .66  .58  .50  .42  .21  .12  .03  -.03  -.07  
4.0  .79  .75  .69  .61  .36  .22  .09  .00  -.05  
6.0  .79  .79  .75  .70  .44  .27  .13  .01  -.04  
6.0  .77  .78  .77  .74  .49  .31  .15  .02  -.04  
10.0  .74  .77  .77  .75  .53  .34  .17  .03  -.03  
15.0  .67  .71  .74  .75  .59  .39  .20  .05  -.03  
20.0  .61  .66  .70  .72  .62  .42  .22  .06  -.02  
Relative Rate of Gross Photosynthesis  -Maximum =  1.0  
0.5  1  1.5  2  4  6  10  20  40  
0.5  .32  .27  .22  .19  .11  .07  .04  .02  .01  
1  .53  .45  .39  .33  .19  .13  .08  .04  .02  
2  .76  .68  .60  .52  .31  .22  .13  .07  .03  
4  .89  .85  .79  .71  .46  .32  .19  .10  .05  
6  .89  .89  .85  .80  .54  .37  .23  .11  .06  
8  .87  .88  .87  *’¦  .QA  .59  .41  .25  .12  .06  
10  .84  .87  .87  .85  .63  .44  .27  .13  .07  
15  .77  .81  .84  .85  .69  .49  .30  .15  .07  
20  .71  .76  .80  .82  .72  .52  .32  .16  .08  

LVOLigniTflDieJUnOO 2/24/07 
PketosunthethiopvamterfforApriladJvm, 1986,LavaoaBof.(from
Table 2 33 
* 
Davis,l9B6) 
9 April 1986 
Time u>. Ps Stnd Alpha Stnd Beta Stnd Pm Stnd Ik 
Err Err Err Err 
6:00 surface 12.20 0.63 .063 .003 .0041 0075 904 004 152 
6.00  bottom  15.07  006  077  .005  .0045  .0009  1200  0.49  157  
1200  surface  2101  202  .078  005  .0025  .0017  18.92  1.13  241  
1200  bottom  26.09  420  .067  005  .0044  .0029  20.41  2.16  304  
1200  sur inc  15.11  307  .047  .004  .0000  .0025  15.11  204  323  
1200  bot inc  21.99  3.43  .066  .005  .0009  .0024  2002  106  309  
1600  sur inc  1008  107  043  003  0005  0010  9.44  001  221  
1600  bot inc  20.93  3.68  .052  .003  .0032  .0028  1606  1.83  318  
1600 sur-botino  1407  1.07  .063  .004  .0015  .0009  12.99  0.63  208  
1600 bot-sur ino  1702  2.11  .060  .006  .0015  0014  1509  127  261  
1800  surface  1702  107  .075  .006  .0041  0017  13.99  0.92  186  
1800  bottom  18.55  224  .063  .005  .0058  .0021  1303  1.11  216  
4 June 1986  
Time  LD.  Ps  Stnd  Alpha  Stnd  Beta  Stnd  Pm  Stnd  Ik  

Err Err Err Err 
600 surface 10.18 1.12 .062 007 .0023 .0013 806 0.68 141 
600  bottom  8.79  OOO  054  .003  0016  0003  708  0.19  142  
1200  surface  12.14  104  058  .006  .0011  0014  11.01  0.92  192  
1200  bottom  1300  005  059  003  0013  0004  11.93  005  201  
1300  sur inc  8.48  101  032  003  0006  .0011  7.72  0.72  245  
1300  bot inc  11.68  0.61  .056  .003  0016  .0005  1024  008  183  
1600  sur inc  5.58  0.73  031  004  0006  .0007  507  0.46  164  
1600  bot inc  15.00  0.63  064  .002  .0035  .0006  12.11  006  190  
1600 sur-bot inc  10.76  125  .053  .005  .0015  0012  9.47  0.75  177  
1600 bot-sur inc  10.96  008  .051  .003  .0010  .0005  9.94  007  195  
1800  surface  9.91  0.90  053  005  0016  .0009  807  005  163  
1800  bottom  1006  007  055  002  0010  0003  902  025  173  
See text for detailsand units.  

CHAPTER 3 
BENTHIC RESPIRATION RATE AND AMMONIUM FLUX 
INTRODUCTION 
Benthic nutrient regeneration provides a significant proportion of 
inorganic nutrients for primary production in shallow marine environments 
Nixon and The
(Fisher et al. 1982, Pilson 1983, Boynton and Kemp 1985). 
potential for nutrient regeneration in sediments is primarily dependent 
upon 
deposition of organic matter from the water column. Estuarine sediments 
with higher organic content support higher microbial metabolism (Waksman and 
Hotchkiss 1938) and result in more regeneration of inorganic nutrients (Seki et 
al. 1968, Aller and Yingst 1980). Nixon and Pilson (1983) reported that the 
benthic remineralization of a marine environment was closely related to the 
into
primary production plus organic input that area. Therefore, higher 
primary production in the water column may result in more nutrient flux from 
sediments in an estuary, unless particulate organic matter in the water column 
is substantially flushed out to the open sea. 
Freshwater inflow is also an important source of inorganic nutrients for 
primary production (Barlow et al. 1963, Sharp 1982, Nixon and Pilson 1983) and 
terrestrial organic matter in estuarine environments (Shultz and Calder 1976). 
Therefore, it is likely that benthic flux of inorganic nutrients may be affected 
by freshwater inflow into an estuarine environment. 
However, little information is available about long term effects of 
freshwater inflow upon benthic nutrient regeneration in an estuarine 
environment. Benthic ammonium flux and oxygen consumption rates were 
measured in the Lavaca Bay estuary, Texas, monthly or bimonthly for two 
consecutive years. During the study period, freshwater inflow into the estuary 
for than for 2
was much greater Year I-''(November 1984-August 1985) Year 
(October 1985-August 1986). 
METHODS 
Deployment of Chambers 
Two opaque fiberglass chambers, A and B (18 liter volume), were deployed 
at station 85 to determine benthic respiration and in situ ammonium flux 
across the sediment-water interface. The chambers were set carefully on the 
seafloor to minimize disturbance of sediments. An (YSI 5139)
oxygen probe 
connected to a dissolved oxygen meter was installed only in Chamber A. 
Chamber water was circulated by a deck-mounted Masterflex pump (Barnant 
Co.) through Tygon tubing (ID 0.63cm, length 2xlsm) wrapped with black 
electrical tape to exclude light. Chamber water was sampled whenever desired, 
via a two-way valve connected to the outlet of the Masterflex pump. 
Circulation of water within the chamber was gentle enough not to disturb the 
surface sediment inside of the chamber. The turnover time of water in the 
chamber via tubing was about 0.5 hour. 
Benthic Respiration Rate 
Benthic respiration rate was determined by measuring the dissolved 
oxygen concentration in the chamber water through time and correcting for 
water volume and chamber area. Since chemical demand was
oxygen not 
determined, these respiration rates are really total oxygen demand (Dale, 1978). 
The concentration of dissolved was measured by both the Winkler 
oxygen 
method and with a polarographic electrode (chamber A), or only by the 
Winkler method (chamber B). Before each experiment, the dissolved oxygen 
meter was calibrated by Comparison with Winkler determinations on identical 
samples of bottom water. During each experiment (about 4 hours), triplicate 
20 ml samples of the chamber water were collected and fixed every 40-50 
minutes for titration. The first sample of chamber water was not collected 
until at least 30 minutes after setting the chambers because was
oxygen 
rapidly consumed at the onset presumably due to disturbance of sediments. All 
Winkler titrations were completed within two hours of sampling. 
Ammonium Analysis of Sediment Pore Water 
Sediment cores were sampled with a core sampler (ID 6.5 cm, height 25 
cm) without disturbing textures of the sediment from seven stations in the 
Lavaca Bay estuary. Sediment cores were sectioned at 1 cm intervals over the 
top 10 cm. Sectioning at 1 cm intervals was judged to be appropriate because 
0.5 ml, the minimum amount of pore water for ammonium was extracted
assay, 
from each section. Each section was into a sterile plastic petri dish which
put 
was then sealed with black electrical to avoid loss of water.
tape any pore 
Replicate samples were frozen immediately and were kept frozen until analyzed. 
Pore water from each sediment section was extracted by centrifugation (5000 x 
g). Ammonium concentration was determined colorimetrically (Solorzano 1969) 
using a spectrophotometer (Beckman Model 24). 
Ammonium Flux 
Benthic ammonium flux across the sediment-water interface was 
determined in two ways. At station 85 the change in ammonium concentration 
of chamber water was measured in situ. Chamber water samples were filtered 
and until
through glass fiber filters (GF/F) were kept frozen analyzed. 
Theoretical ammonium flux (calculated ammonium flux) of each station was 
calculated from the profile of ammonium concentrations in’
independently 
sediment pore waters. The theoretical calculation is based on Pick’s first law, 
and the following equations were used (Klump and Martens 1981). 
J 0D 
s-Os 
pw 
J = flux of ammonium across the sediment (jug-at N m hour *)
s 
0 = porosity at the sediment-water interface (unitless)
O 
91 
D = bulk sediment diffusivity (cm .sec *)
s pW 
D— = 
Ss ®oF 

where 
D 0 = molecular diffusivity of ammonium sec *) (Klump and FW 
Martens 1981) 
F = formation resistivity factor (Ullman and Aller 1982) 
F = 0> 0.7,m=3;for0< 0.7,m=2) 
dC 
(~1 = gradient of ammonium concentration at the sediment-water 

aZ. 
P
w interface 
The gradient was calculated by three different ways as described below. The 
method used depended on the pattern of the profile of ammonium concentration 
in the sediments. 
1) When the ammonium concentration increased linearly with depth into 
the sediment, the gradient was obtained from the slope of 
concentration versus depth. 
2) When ammonium concentration increased exponentially with 
sediment depth, the gradient was obtained as follows (Klump and 
Martens 1981): 
=a ­
(C Co) e~QZ 
pw 
a = constant 
=
z depth (cm) 
C C concentration of ammonium at depths z, infinity and zero 
z, ,C0; 
1 (the sediment-water interface) respectively (/zg-at NT ) 
3) When the ammonium concentration of the top sediment section 
to or
(0-1 cm) was equal higher than that of pore water of the next 
lower sediment section (1-2 cm), the gradient was calculated using 
the following equation: 
-
[NH4+] of the top sediment [NH4+] of the overlying water 
(f 2­
pw 
0.5 cm 
This calculation is based on arbitrary assumptions that; (1) 
ammonium concentration in the pore water increases linearly with 
depth within the upper 1 cm of sediment, and (2) that the 
ammonium concentration at the sediment-water interface 
was 
identical to that of water. These assumptions not be
overlying may 
appropriate in all cases. However, this calculation may provide 
relative values of theoretical flux and allow us to the flux
compare 
at different stations when ammonium concentration is maximal in the 
top sediment section. 
Porosity of sediments (Table 3.1) was determined using the following equation: 
Porosity (0) = water content of sediment/volume of sediment 
Water content of the sediment was measured as the difference in weight 
between the wet sediment and the dry sediment (dried at 45°C for two weeks). 
The porosity at the interface (o 0) was the intercept at the 
sediments when the the versus’
zero depth of extrapolating slope of porosity 
the depth of sediments (upper few cm). 
RESULTS 
Dissolved Oxygen Concentration 
Dissolved concentration of bottom water at Lavaca Bay station 85
oxygen 
generally decreased as temperature increased. During Year 1, the highest 
oxygen concentration (12.0 mg/1) was in January and the lowest concentration 
(6.8 mg/1) was in July. During Year 2, the highest concentration (9.8 mg/1) 
was in December and the lowest concentration (5.94 mg/1) was in August. 
dissolved concentration was in Year 1 than
Through the seasons, oxygen higher 
in Year 2 (Fig. 3.1). The percent saturation of dissolved oxygen was also 
higher during year 1 than during Year 2 (Fig. 3.2). The highest saturation 
(122.8%) was in April of 1985 and the lowest (80.8%) was in August of 1986. 
The percent saturation was generally higher in the winter than in the summer 
during the two year study period. 
Benthic Respiration Rate (total oxygen consumption rate in the chamber water 
Seasonal patterns of benthic respiration rates of Year 1 and Year 2 were 
different (Fig. 3.3). Benthic respiration rate is generally related to 
temperature (Hargrave, 1969). In this study area, benthic respiration rate 
appeared to be not significantly related to temperature (r = 0.15; p > 0.1) or 
= the two
to salinity (r 0.45, p > 0.05) during year study period (Fig. 3.4.1, 
h
Fig. 3.4.2). During Year 1, the highest respiration rate (311 O 2 -*)
mg 
h 
was in the coldest month (January) and the lowest value (106 O 2 -*)
mg 
7 
was in June. During Year 2, 'the highest oxygen consumption rate (412 mg O2 
m"2 h-1) was in June and the lowest rate (132 mg O 2 h'*) was in October 
(Fig. 3.3). 
The range of oxygen consumption rates in the study area was much 
higher than that observed in North Carolina estuaries (Fisher et al. 1982), or 
the and
that measured along salinity gradient of Chesapeake Bay (Boynton 
Kemp 1985). However, the range of respiration rates in the study area were 
similar to those observed in Corpus Christi Bay (Flint and Kalke 1985). 
Ammonium Concentration in Sediment Pore Water 
In general, ammonium concentrations in pore waters of surface sediments, 
particularly in the upper few cm, were higher during Year 1 than during Year 
2 for all stations in the Lavaca Bay estuary (Table 3.2, 3.3, 3.4). However, 
ammonium concentration in water of sediments did not show a trend
pore 
along the salinity gradient. The most conspicuous result of this study was the 
difference in the dominant pattern of ammonium concentration profiles between 
Year 1 and Year 2. During Year 2, ammonium concentration generally 
increased with depth of sediments except station 65 (Fig. 3.5.1, 3.5.2.2, 3.5.3.2, 
3.5.4.2, 3.5.5.2, 3.5.6.2, 3.5.7.2). In contrast, during Year 1 the dominant 
pattern of ammmonium profiles was reversed; ammonium concentration of the 
-
top sediment pore water (0 1 cm) was generally higher than those of deeper 
sediments (Fig. 3.5.1, 3.5.2.1, 3.5.3.1, 3.5.4.1, 3.5.5.1, 3.5.7.1). 
During Year 1, the range of ammonium concentration in pore water of 
-
upper 10 cm sediments was 9.6 1793 /xg-at N 1" More than 1700 /xg-at N 
. 
1I"was observed in pore waters of station 45, 603, 613, 623, 633, and 1505. 
-
The range for Year 2 was 27.1 1033 /xg-at N I"*. The of ammonium
range 
concentration of sediment pore water in the study area is greater than that of 
et al. and that River
the Tarmar Estuary of England (Watson 1985) of Indian 
et al. it smaller than that of
estuary, Florida (Montgomery 1979). However, is 
Cape Lookout, North Carolina (Klump and Martens 1981); that of the White 
Oak River North Carolina (Martens and Goldhaber 1978); or that of
estuary. 
Ronbjerg Harbour in Denmark (Henriksen et al. 1980). 
Ammonium Flux 
During three of the seven chamber experiments in Year 1, the ammonium 
flux was from the water column into sediments rather than from sediments to 
the water column in (April, 1985) or was not significantly different from zero 
(January, July 1985) (Fig. 3.6). However, in March 1985, ammonium flux from 
sediments was greater than 2000 /xg-at N h~*. The ammonium flux for 
Year 2 was greater than for Year 1 for all months March, 1985. The
except 
variation of the flux during Year 2 was smaller than that of Year 1. The 
range of in situ ammonium flux was from 94 /xg-at N hT* to 2397 /xg-at N 
IT* at station 85 over the two year study period. This range is greater 
than those observed by Fisher et al. (1982) in a North Carolina estuary, Klump 
and Martens (1981) in Cape Lookout Bight, or Boynton and Kemp (1985) in the 
Chesapeake Bay estuary. The measured flux did not show any significant 
=
relationship to temperature (r = -0.23; p > 0.1) or to the salinity (r 0.04; p > 
0.1) in this study area (Fig. 3.7.1, Fig. 3.7.2). 
The theoretical fluxes (calculated fluxes) of year I were higher than 
those of Year 2 (Fig. 3.8). During Year 1, the calculated flux ranged from 
N and
40.3 /xg-at N m~2 h'* to 1058 /xg-at h'*, during Year 2, it ranged 
from 3.6 N m to 240 N m h‘l The theoretical flux
/xg-at /xg-at 
=
(calculated flux) also did not show any relationship to temperature (r -0.42; 
p > 0.05) during the study period (Fig. 3.9.1). However, the theoretical flu* 
=
decreased as salinity increased at station 85 (r -0.63, p < 0.01) (Fig. 3.9.2). 
Theoretical fluxes at station 85 were calculated using mostly ammonium 
concentration of top sediment section (0 1 cm) and that of the overlying
-
water (Fig. 3.10). Therefore, higher ammonium concentrations of top sediment 
pore waters in Year 1 (wet year) relative to those in Year 2 (dry year) seems 
to be responsible for such a relationship. Relatively high calculated fluxes 
were shown right before the coldest season (November in the first year, 
October in the second year) and at mid summer (August for both Year 1 and 
year 2). The calculated flux was generally higher (except for March 1985) 
than the measured flux during Year 1, while the measured flux was higher than 
the calculated flux during Year 2 (Fig. 3.10). We expected that the calculated 
flux would positively correlate with the measured flux as reported by Klump 
and Martens (1981). However, substantial discrepancy between calculated and 
measured flux was observed in this study (Fig. 3.10). But the highest peak of 
both the measured and the calculated flux at station 85 commonly appeared in 
March 1985. 
-
All raw data from this study are presented in appendices Tables 3.1 3.7. 
DISCUSSION 
Ammonium concentration in pore water of sediments depends on 
ammonium regeneration and utilization microbes
rate rate by (Blackburn 1979, 
Williams et al. 1985) and also on advection and diffusion of pore water across 
the sediment-water interface (Aller 1980, Watson et al. 1985). In general, 
ammonium regeneration rates are relatively high near the sediment-water 
interface and decrease with depth (Blackburn 1979, Aller and Yingst 1980, 
Nixon and Pilson 1983), while ammonium concentration in sediment pore water 
is relatively lower at the interface and increases with depth (Klump and 
Martens 1981). Ammonium in pore water closer to the interface is more 
readily utilized by benthic algae or nitrifying bacteria, and is more easily 
transported into the water column. Therefore, higher turnover rates of 
ammonium are probably responsible for relatively lower concentration in upper 
sediment pore water compared to deeper sediments in typical estuarine 
environments. 
It is rarely reported that ammonium concentration in pore water of the 
upper 1 cm of sediments is higher than that of deeper sediment. However 
such a profile predominated during Year 1 (Figs. 3.5.1, 3.5.2.1, 3.5.3.1, 3.5.4.1, 
3.5.5.1, 3.5.6.1, 3.5.7.1). A similar profile was reported from the tributary area 
of Chesapeake Bay (Boynton and Kemp 1985). In general, during Year 2, 
ammonium concentrations were either uniform through the depth of sediments 
or increased with depth. 
It is possible that the difference in freshwater inflow between Year 1 and 
Year 2 may be responsible for the difference in ammonium concentrations of 
pore waters and their profiles between Year 1 and 2. Primary productivity 
measurements for Year 1 are not available for comparison with Year 2. 
However, freshwater inflow and inorganic nutrient concentrations were much 
higher during Year 1 than during Year 2 (Chapter 2 of this report). 
Chlorophyll a concentration also appeared to be higher during Year 1 than 
during Year 2 (Chapter 2 of this report). Therefore, primary production of 
Year 1 might have been higher than that of Year 2. Higher percent saturation 
of dissolved oxygen during Year 1 supports higher photosynthetic activity in 
Year I because higher dissolved oxygen is usually observed in seawater where 
photosynthetic activity is more active (Sharp et al. 1982). Higher primary 
in column due to freshwater have
production the water greater inflow may 
increased the deposition of organic matter and eventually enhanced ammonium 
regeneration in upper surface sediments. 
Freshwater inflow with its terrestrial organic matter may directly increase 
organic deposition. In general, terrestrial organic matter contains a high 
proportion of humic substances (Beck and Reuter 1974) which are refractory to 
bacterial metabolism. However, it cannot be ruled out that an increase in 
deposition of terrestrial organic matter may have been responsible for higher 
ammonium concentrations in pore water in the upper sediments during Year 1. 
Even though we don’t know either the pool size of total nitrogen in 
surface sediments or main related to ammonium remineralization, we
processes 
can state that the ammonium pool in surface sediments was larger with greater 
freshwater inflow in the Lavaca Bay estuary. 
Ammonium flux is usually determined by in situ measurement using 
benthic chambers or by using the profile of ammonium concentrations in 
sediment pore waters to calculate a flux. Each of these two methods has 
intrinsic limitations and assumptions. When a benthic chamber is used for 
measurement, the following problems may cause erroneous results: (1) 
ammonium concentration in the chamber water may change due to disturbance 
of sediments; (2) non-chamber water may enter during sampling of chamber 
water; (3) significant amounts of ammonium may be utilized or produced inside 
the and
chamber; (4) measurements in a closed system may not represent the 
natural system. Calculation of the theoretical flux is based on the following 
assumptions: (1) diffusion of ammonium is the main factor controlling mobility 
of ammonium in sediment por6 waters; (2) the ammonium concentration profile 
in the pore water of upper sediments is in steady state; and (3) there are no 
physical, chemical or biological barriers between sediments and the sediment-
water interface which may influence diffusivity of ammonium. However, these 
flux
assumptions are not always met. For example, ammonium is sometimes 
enhanced by bioturbation (Aller 1980; Henrikson et al. 1980; Calender and 
Hammond, 1982; Lyons et al., 1982), and benthic microalgae (Henriksen et al., 
1980; Williams et al. 1985) and other microorganisms in the upper sediments 
water.
may utilize ammonium substantially prior to diffusion into the overlying 
Flux of inorganic nutrients measured in situ generally yields higher values 
than calculated flux due to bioturbation in surface sediments. For example, 
Lyons et al. (1982) reported that the measured flux was 3-6 times higher than 
the calculated flux at Potomac River Estuary in Chesapeake Bay, and Callender 
and Hammond (1982) reported than the measured flux was 1-10 times higher 
than the calculated flux in Great Bay Estuary in New Hampshire. At station 
85 in the Lavaca Bay estuary, the measured flux of ammonium was 2-200 times 
higher than the calculated flux during Year 2. In contrast, the calculated flux 
was generally higher than the measured flux during Year 1. The sharp 
ammonium gradient probably existed within a very shallow depth of sediments 
during Year 1. However, ammonium concentration of the top sediment (0-1 
cm) pore water and that of the overlying water were used for calculation of 
the theoretical flux because ammonium concentration of the sediment (0-1
top 
cm) pore water was higher than that of the adjacent deeper sediments through 
the year. Calculated fluxes of Year 1 are probably overestimated because the 
ammonium concentration at the sediment-water interface is presumably much 
than that the flux measured
higher of overlying water. Therefore, ammonium 
from the chamber .experiment is more reliable than calculated flux. A primary 
calculated and measured flux is the
cause of discrepancy between excessively 
high fluxes of ammonium calculated when ammonium concentration was maximal 
in the top sediment (0-lcm) during Year 1 (Fig. 3.8). 
In situ ammonium flux measured at station 85 in March of Year 1 was 
extraordinarily high (more than 2000 /xg-at N h“*). This was probably 
related to the very high concentration of ammonium in pore water (1590 /xg-at 
short of
N I" 1 in the top sediment). Such a non-seasonal, term peak pulse 
sediment nutrient regeneration was probably due to rapid degradation of newly 
sedimented material at the sediment surface (Fisher et al. 1982). 
During Year 1, measured ammonium flux was not significantly different 
from zero in January and July (95% confidence interval was -10.8 + 472.4 /xg­
atm N and -7.0 + 17.6 /xg-atm N respectively), and negative 
ammonium flux (from the water column to sediments rather than from 
sediments to the water column) was found in April (95% confidence interval 
was -94.2 + 5.1 /xg-atm N m‘V*). During those periods when a flux was zero 
or negative, most regenerated ammonium might have been consumed by 
microorganisms or benthic algae near the sediment-water interface prior to 
diffusion into the water column. Williams et al. (1985) also reported that 
negative flux may occur if regenerated ammonium is substantially utilized by 
benthic algae or nitrifying bacteria in surface sediments. 
Edwards (1981) discussed that alteration of freshwater inflow causes 
change in salinity of benthic environments, resulting in alteration in physical 
and chemical parameters of sediments in addition to biological metabolism. We 
did not measure physical parameters of surface sediments like pH and redox 
potential. However, we can speculate that alteration in such physical 
for difference in
parameters may be the other possible explanation the 
ammonium flux between Year I and Year 2 because pH and redox potential are 
important factors to mobility of ammonium (Graetz et al., 1973). 
Fisher et al. (1982) reported that there was no significant relationship 
between consumption rate and in situ ammonium flux in North Carolina
oxygen 
estuaries. We also did not observe a strong relationship between those two 
in the area. Klump and Martens (1981) observed that
parameters study 
ammonium release from sediment was strongly dependent on temperature in the 
Cape Lookout Bight. In our study area, no significant relationship was 
observed between temperature and in situ ammonium flux. Other processes or 
parameters probably played more important roles in releasing ammonium from 
sediments in our study area. 
The demand for regenerated nitrogen in the water column was not 
directly assessed in this study. However, simple calculations can be made to 
obtain rough estimates for comparison with benthic flux measurements. 
For 
example, one can multiply primary production (mg Om~2*d“l; Davis, 
1986) by a conversion factor relating nitrogen uptake to carbon assimilation. 
1The Redfield ratio of phytoplankton (by weight 6.0 mg Omg N"; Redfield 
et al. 1963) is commonly used for this purpose. Two examples are presented: 
Month: April 1986 
Primary Production: 1111 Om-2 d~* 
mg 
-
Demand for N: 1111 mg Cm‘* 6.0 mg Omg N“* 
2 _1 
= 
185.2 N-m--d
mg 
= 13.2 mg-at N-m-2-d"^ 
Month; June 1986 
Primary Production: 1819 mg C-m“2-d“^ 
2* * Demand for N; 1819 mg Cm -d 6.0 mg C-mg N 
2l = 303.2 N-m~-d~
mg 
2-d“*
= 
21.6 mg-at N-m~
These daily rates could be divided by 24 to get very rough estimates of 
the demand for nitrogen in units comparable to the benthic flux measurements: 
2 April calculated demand = 550 N-m'June demand = 900 /zg-at N-m~ 
2*h~l. There are problems associated with this method of estimation: the 
many 
Redfield ratio not the chemical composition of the 
may represent 
phytoplankton (C/N might be higher, thus nitrogen demand would be 
overestimated, perhaps by up to two times); bacterial demand for ammonium is 
not assessed (Wheeler and Kirchman 1986) leading to a potentially sizeable 
underestimation of the demand for nitrogen; nocturnal respiration of the 
phytoplankton is not considered and thus the true ratio of carbon taken up 
during the day to nitrogen assimilated over 24 h is underestimated and the 
-
demand for nitrogen is overestimated, maybe by as much as 1.5 2 times. 
There is also a problem associated with interpretation of incorporation. 
Does the method measure gross or net production? Without getting involved in 
further discussion we can state that demand for regenerated nitrogen in the 
water column is on the same order of magnitude as the measured benthic flux 
_2(442 /ig-at N-m“2 in April, 682 /xg-at N-m-h in June) and that 
quantitative relationships must be determined with more involved techniques 
including studies with nitrogen and carbon tracers. 
CONCLUSION 
The ammonium pool in surface sediments, particularly the upper few cm, 
Year 1 than Year 2 in
was generally higher during (wet year) during (dry year) 
the study area. The profiles' of ammonium concentrations in sediment pore 
waters for the wet were different from those for the During
year dry year. 
the wet ammonium concentrations in the few cm of sediment
year, upper pore 
waters were generally higher than in deeper sediments. In contrast, during 
the dry year, ammonium concentrations in the upper few cm were generally 
lower than in the deeper sediments. Calculated ammonium fluxes were greater 
than in situ measured fluxes in the wet whereas calculated fluxes were
year, 
smaller than the measured fluxes in the dry year. Discrepancy between 
calculated and measured ammonium flux may be due to overestimation of 
calculated flux when ammonium concentration was maximal in sediment (0-1
top 
the the measured
cm) during wet year. Therefore, flux represents more 
reliable estimate of ammonia flux. Neither the calculated flux the
nor 
measured flux was correlated with temperature. Though measured ammonium 
flux did not show a significant relationship with salinity, calculated flux 
decreased as salinity increased. Benthic respiration rate did not show a 
significant relationship with temperature or salinity during the study period. 
REFERENCES 
Aller, R.C. 1980. Diagenetic processes near the sediment-water interface of 
Long Island Sound. I. Decomposition and nutrient element geochemistry. 
Advances in Geophysics 22:237-350. 
R.C. and J.Y. Yingst. 1980. Relationships between microbial distributions
Aller, 
and the anaerobic decomposition of organic matter in surface sediments of 
Island Sound, U.S.A. Mar. Biol. 56:29-42.
Long 
Barlow, J.P., C.J. Lorenzen and R.T. Myren. 1963. Eutrophication of a tidal 
estuary. Limnol. Oceanogr. 8:251-262. 
Beck, K.C. and J.H. Reuter. 1974. Organic and inorganic geochemistry of some 
coastal plain rivers of the southeastern United States. Geochim. 
Cosmochim. Acta 38:341-364. 
Blackburn, T.H. 1979. Method for measuring rates of NH4+ turnover in anoxic 
15 
marine sediments, using a N-NH4+ dilution technique. Appl. Environ. 
Microbiol. 37:760-765. 
Boynton, W.R. and W.M. Kemp. 1985. Nutrient regeneration and oxygen 
Mar. Ecol.
consumption by sediments along an estuarine salinity gradient. 
Prog. Ser. 23:45-55. 
Callender, E. and D.E. Hammond. 1982. Nutrient exchange across the sediment-
water interface in the Potomac River Estuary. Estuarine, Coastal and 
Shelf Science 15:395-413. 
Dale, T. 1978. Total, chemical and biological oxygen consumption of the 
sediment in Lindaspollene, Western Norway. Mar. Biol. 49:333-341. 
Davis, R.F. 1986. Measurement of primary production in turbid water. M.A. 
Thesis. University of Texas. 
Edwards, R.E. 1980. The influence of salinity transition on benthic nutrient 
regeneration in estuaries. Proceedings of the National Symposium on 
Freshwater Inflow to Estuaries. Vol. 11. Ed. by R.D. Cross and D.L. 
Williams, 2-16. 
pp. 
Fisher, P.R. Carlson and R.T. Barber. 1982. Sediment nutrient
T.R., 
regeneration in three North Carolina estuaries. Estuarine, Coastal and 
Shelf Science 14:101-116. 
Flint, R.W. and R.D. Kalke. 1985. Benthos structure and function in a South 
Contributions in Marine Science 28:33-53.
Texas estuary. 
Graetz, D.A., D.R. Keeney and R.B. Aspiras. 1973. Eh status of lake sediment-
water systems in relation to nitrogen transformations. Limnol. Oceanogr. 
18:908-917. 
Hargrave, B.T. 1969. Similarity of oxygen uptake by benthic communities. 
Limnol. Oceanogr. 14:801-805. 
Henriksen, K,, J.I. Hansen and T.H. Blackburn. 1980. The influence of benthic 
infauna on exchange rates of inorganic nitrogen between sediment and 
water. Ophelia, Suppl. 1:249-256. 
Klump, J.V. and C.S. Martens. 1981. Biogeochemical cycling in an organic rich 
-
coastal marine basin 11. Nutrient sediment-water exchange processes. 
Geochim. Cosmochim. Acta 45:101-121. 
Lyons, W.8., T.C. Loder and S.M, Murray. 1982. Nutrient pore water chemistry. 
Great Bay, New Hampshire: benthic fluxes. Estuaries 5:230-233. 
Maclsaac, J.J. and R.C. Dugdale. 1972. Interactions of light and inorganic 
nitrogen in controlling nitrogen uptake in the sea. Deep-Sea Res. 19:209­
232. 
Martens, C.S. and M.B. Gofdhaber. 1978. Early diagenesis in transitional 
sedimentary environments of the White Oak River Estuary, North 
Carolina. Limnol. Oceanogr. 23:428-441. 
Montgomery, J.R., C.F. Zimmermann and M.T. Price. 1979. The collection, 
analysis and variation of nutrients in estuarine pore water. Estuarine and 
Coastal Mar. Sci. 9:203-214. 
Nixon, S.W. and M.E.Q. Pilson. 1983. Nitrogen in estuarine and coastal marine 
ecosystems. In: Nitrogen in the Marine Environment. Ed. by E.J. 
Carpenter and D.G. Capone. Academic Press, New York. pp. 565-648. 
Redfield, A.C., B.H. Ketchum and F.A. Richards. 1963. The influence of 
the of
organisms on composition seawater. In: The Sea, Volume 2, Ed. by 
M.N. Hill.  Interscience, New York.  pp.  26-77.  
13  12  
Shultz,  DJ.  and  J.A.  Calder.  1976.  Organic  carbon  C/  C  variations  in  

estuarine sediments. Geochim. Cosmochim. Acta 40:381-385. 
Seki, H., J. Skelding and T.R. Parsons. 1968. Observations on the 
decomposition of a marine sediment. Limnol. Oceanogr. 13:440-447. 
Sharp, J.H. 1982. The chemistry of the Delaware estuary. General 
considerations. Limnol. Oceanogr. 27:1015-1028. 
Solorzano, L. 1969. Determination of ammonia in natural waters by the phenol 
hypochlorite method. Limnol. Oceanogr. 14:799-801. 
Ullman, W.J. and R.C. Aller. 1982. Diffusion coefficients in nearshore marine 
sediments. Limnol. Oceanogr. 27:552-556. 
Waksman, S.A. and M. Hotchkiss. 1938. On the oxidation of organic matter in 
marine sediments by bacteria. J. Mar. Res. 1:101-119. 
Watson, P.G., P.E. Frickers and C.M. Goodchild. 1985. Spatial and seasonal 
variations in the chemistry of sediment interstitial waters in the Tamar 
Estuary. Estuarine, Coastal and Shelf Science 21:105-119. 
Wheeler, P.A. and D.L. Kirchman. 1986. Utilization of inorganic and organic 
nitrogen by bacteria in marine systems. Limnol. Oceanogr. 31:998-1009. 
Williams, S.L., S.M. Yarish and I.P. Gill. 1985. Ammonium distributions, 
production, and efflux from backreef sediments, St. Croix, U.S. Virgin 
Islands. Mar. Ecol. Prog. Ser. 24:57-64. 
Figure 3.1. Bottom Water Dissolved Oxygen (station 85) Data in Appendix 3.1 
85) 
(station 
Oxygen 




Dissolved 

of 

Saturation 

Percent 

3.2. 
Figure 
85) 
(station 

rate, 

respiration 

chamber Benthic 
3.3. 
Figure 
3.3). 
Appendix 

in 
(Data 
Figure 3.4.1. Relationship of Benthic Chamber Respiration Rate To Temperature at Station 85 ( 1984-1986) 
Figure 3.4.2. Relationship of Benthic Chamber Respiration Rate To Salinity at Station 85 ( 1984-1986) 
Figure 3. 5.1 Profiles of ammonium concentrations in sediment pore waters at station 45, (Data in Appendix 3.4) 
Figure 3.5.2.1. Profiles of ammonium concentrations in sediment pore waters at station 603 in Year 1 (Data in Appendix 3.4) 
Figure 3.5.2.2. Profiles of-ammonium concentrations in sediment pore waters at station 603 in Year 2 (Data in Appendix 3.4) 
Figure 3.5.3.1. 	Profiles of ammonium concentrations in sediment pore waters at station 65 in 1.
Yecir (Data in Appendix 3.4) 
Figure 3.5.3.2. Profiles of ammonium concentrations in sediment pore waters at station 65 in Year 2. (Data in Appendix 3,4). 
3.5.4.1. 	waters at station 613 in Year 1. (Data in Appendix 3.4). 
Figure Profiles of ammonium concentrations in sediment pore 
Figure 3.5.4.2. 	Profiles of ammonium concentration's in sediment pore waters at station 613 in Year 2. 
(Data in Appendix 3.4). 
Figure 3.5.5.1. Profiles of ammonium concentrations in sediment pore waters at station 623 In Year 1. (Data in Appendix 3.4). 
Figure 3.5.5.2. Profiles of ammonium concentrations in sediment pore waters at station 623 in Year 2. (Data in Appendix 3.4). 
Figure 3.5.6.1. 	Profiles of ammonium concentrations in sediment pore waters at station 633 in Year 1. 3.4).
(Data in Appendix 
3.5.6.2. Profiles of ammonium concentrations in sediment pore waters
Figure 
at station 633 in Year 2. (Data in Appendix 3.4), 
Figure 3.5.7.1. Profiles of ammonium concentrations in sediment pore waters at station 85 in Year 1. (Data in Appendix 3.4). 
Figure 3.5.7.2. Profiles of ammonium concentrations in sediment pore waters at station 85 in Year 2. (Data in Appendix 3.4). 
station 

at 
chambers 

situ 
in 
from 
measured 

flux 
Ammonium 

3.6. 
Figure 
3.6). 
Appendix 

in 
(Data 
Figure3.7.1. RelationshipofMeasuredAmmoniumFluxFromInSituChambers ToTemperature at Station 85 ( 1984-1986) 
Figure 3.7.2. Relationship of Measured Ammonium Flux From In Situ Chambers To Salinity at Station 85 ( 1984-1985) 
Aug'86
' 
. 
Jun'86
3 
*45 *603 *65 *61 *85 *623 *633 1 
Stn Stn Stn Stn Stn Stn Stn 
LftrL Apr'86 
B0 m0.S§ 
i 
-
’S£
concentration v r" 
¦ i— F*?b 
0<?c'85
ammonium 
Oot’85
from LlJ 
? 
Aug’85
¦ 
¦ 
Date
(calculated >* / 
: ;>/ 
Jul'85
Itli\ ii 
Sample 
i5S [/
flux un’85 
. 
5; 
v. 
3.7 
\ 
¦4 :¦*
ammonium sediments). May'85Appendix i 
* . / y/////05
* 
li 
in Apr'85
\ 
in
Theoretical profiles 
. 1i 
1
Data Mar'85 
*; 
/V / *' *' \'A/
3.8. ian'85
1( 
Figure 
-
7yy.../K-)Ayyyy1y/L/* /¦ YYYy'Y/YYYy //I 
liiii 
Nov'84 
‘ 
1200 1000 800 600 400 200 0 
a. wVCl
/¦“N£ LtjM s N atm(jig— Flux 
( 
' 
Figure 3.9.1. Relationship of Theoretical Ammonium Flux To Temperature at Station 85 ( 1984-1986) 
Figure 3.9.2. Relationship of Theoretical Ammonium Flux To Salinity at Station 85 ( 1984-1986) 
Flux 
Ammonium 
Theoretical 

of 
Comparison 

3.10. 
Figure 

85 
Station 

at 
Flux 
Measured 

With 
Porosity of Sediments
Table 3.1. 
100
Porosity=((sample vetweight-sample dryweight)/samplevolume)*
* = 34.19 cm*3
Sample Volume (3.3) *2 *3.14 
Jun‘86 (cm) % (g/cm‘3) AYE (cm) % (g/cm‘3) AYE 
Station* Depth Apr‘86 Jun‘86 Aug*86 Station* Depth Apr‘86 Aog‘86 
0-1 71.5 86.5 67.5 75.2
45 0-t 58.9 71.7 69.9 66.8 603 
1-2 89.9 48.5 69.0 1-2 87.4 80.1 65.9 77.8
68.7 
85.9 63.9 79.9
2-3 61.8 58.0 46.2 55.3 2-3 89.9 
70.9 60.7
3-4 56.8 68.1 48.3 57.7 3-4 83.3 87.9 
4-5 53.9 80.4 50.2 61.5 4-5 64.9 66.2 ?1.3 80.8 5-6 41.3 85.9 46.6 57.9 5-6 78.9 89.3 61.6 
76.6 
6-7 48.2 75.4 43.9 55.2 6-7 77.1 84.9 78.5 80.2 7-8 44.5 78.2 37.9 53.5 7-8 86.5 87.8 68.6 81.0 8-9 45.4 70.1 41.2 52.2 8-9 86.5 91.3 72.8 83.5 
9-10 34.1 62.9 46.1 47.7 9-10 87.1 82.1 64.6 77.9 
69.0
65 0-1 86.2 56.0 61.9 68.0 613 0-1 61.6 65.3 60.0 
1-2 61.3 44.1 54.2 53.2 1-2 77.6 82.2 77.8 79.2 
36.8 44.3 80.3 85.4 82.0
2-3 41.1 55.1 2-3 80.2 
57.1 3-4 74.7 69.1 93.4 79.1
3-4 37.4 38.4 44.3 
4-5 38.9 49.9 51.7 4-5 75.7 65.6 81.8 74.4 5-6 61.5 35.1 58.3 51.6 5-6 73.0 64.4 77.5 71.6 6-7 60.0 31.7 51.4 47.7 6-7 70.3 72.3 79.8 74.1 
7-8 64.9 39.9 45.9 50.2 7-8 71.5 68.5 
66.2 
80.7 73.5 
8-9 47.4 54.3 43.3 48.3 8-9 75.6 64.2 76.3 72.0 9-10 60.7 43.4 45.8 50.0 9-10 69.5 90.2 
78.9 79.5 
0-1 81.6 77.3
85 0-1 79.4 70.9 69.4 73.2 623 81.6 68.6 1-2 60.3 68.1 71.3 66.6 1-2 69.8 80.7 61.5 70.7 2-3 64.8 67.5 71.5 67.9 2-3 58.9 69.2 64.3 64.1 
3-4 61.0 73.9 54.1 63.0 3-4 60.8 58.9 
60.9 60.2 4-5 58.0 57.6
4-5 62.1 73.9 60.1 65.4 59.6 55.1 
5-6 89.4 70.1 5-6 61.3
68.9 76.1 58.1 59.8 59.7 6-7 64.7 62.8 55.0 60.8 6-7 60.1 59.4 55.2 58.2 7-8 82.4 61.6 72.4 72.1 7-8 69.6 
61.0 60.5 63.7 
63.1 8-9 55.8 57.1 50.9 54.6
8-9 75.5 61.9 51.8 
9-10 56.0 54.8 59.3 56.7
9-10 74.0 77.8 63.7 71.8 
71.9
633 0-1 73.0 69.9 72.7 
1-2 51.9 56.8 67.3 58.7 2-3-54.9 47.4 63.7 55.3 3-4 60.3 43.6 65.1 56.3 4-5 59.1 45.9 60.9 55.3 5-6 59.6 38.3 75.1 57.7 6-7 66.0 42.4 68.8 59.1 7-8 68.9 37.8 61.6 56.1 8-9 63.0 31.8 65.2 53.3 
9-10 54.4 47.4 63.8 55.2 
APRIL 
*2, 
.1 .2 
613 63.9 43.8 38.9 105.1 143.7 172.9 633 192.9 218.5 449.2 486.0
YEAR r'r«2 ir*2 151 421 
ys. Mean Mean 1 

*1 Station Yr*1 763.3 539.8 528.6 365.7 378.3 387.3 Station Yr*1 1793.5 1444.0 756.0 1356.0 994.0 
YEAR 
SEDIMENTS 
2 
n
DEEP Yr»2 177.04 160.37 144.00 191.9 139.0 163.7 623 Yr 78.0 98.2 103.9 117.5 114.8 129.8 v/ater.
65 
*2).
Mean 	Mean 
.5
AND 	1.4 pore
1	1 
* 98* Yr Yr101 of
Station 207.5 629.2 334.6 278.0 108.7 Station 644.9 582.2 582.8 748.2 174.1 (Year 
liter
1986
SURFACE 
per 
N
April 	­p.g-atm 
IN 
*1) 
(Year 	units
CONCENTRATION 	and 
603 .93 	.0
93.4 72.6 	41 76.8 85.2 87.7
Vr*2 	135.54 169.88 294.0 325.9 354.2 85 Vr«2
131 	1985
Mean 	Mean
3.2. Station Station 	concentration
April
*
793.1 590.4 569.6 384.6 360.5 365.4 	922.3 702.1 .6 182.8 148.5 188.0
Yr*1 	Yr1 291
AMMONIUM
Table 	for 
are 
Ammonium
1	1
3	2
-2 	Data 
-
1
Depth Interval (cm) 0-2 7-8 8-9 0 Depth Interval (cm) 2-3 7-8 8-9 9-10 
1
1	0 
cr. 
JUNE 
•2, 
——
YEAR 613 *2 65.7 75.6 72.6 74.8 92.5 115.1 633 .4 352.7 393.4 227.9 
Yr Yr*2 121 
ys. Mean Mean 

—
66.6 84.3 
*1 Station 678,6 747.3 582.2 365.4 200.9 202.1 Station 372.0 105.4
Yr*1 Yr*1 
YEAR 

SEDIMENTS 
DEEP 53.6 81.0 85.5 44.0 69.3 41.3 623 V#2 43.1 105.4 136.5 165.1 172.6 189.2 v/ater.
65 
Yr«2 Mean Mean V *2)
AND pore
.1 .2.2.9 .8.8
74.4 16.0 17.2 30.1 30.7
262164 89 51
Station 104.1 Station
521 of
Yr*1 Yr*1 (Year liter
986
SURFACE 1 
1 
per 
; 
M
IN 
June 
Hg-atm 
*1) = 
units
(Year
7, .9 .1.5
CONCENTRATION and 
603 67.8 84 84.0 159.6 178.0 193.1 85 71.1 81 70.2 71 74.4 86
Yr*2 Yr*2 
Mean Mean

3.3. Station Station 1985 concentration
11 
» 259.5 169.9 213.0 60.5 243.8 192,2 * 225.7 120.7 133.4 54.3 103.0 148.2 June 
1
Vr Vr
AMMONIUM
Table for 
are 
Ammonium
1 
23 8
1 
23 8 
-
i
Depth Interval (cm) 3-9 o Depth Interval (cm) 8-9 9-10 Data 
027
11
0 27 
•JO 
AUGUST 
»2, 
613. .0 633
125.6 138.9 146.6 132.2 130.4 133.1 240.1 294.9 335.2 352.7 342.5
91 
Yr*2
YEAR Yr*2 
Mean Mean 

ys. 
Station 802.7 735.2 159.6 364.2 365.1 428.6 Station 1709.9 1712.0 1712.7 430.4 381.9
Yr**1 Yr*1
*1 
YEAR 
SEDIMENTS 
65 *2 164.5 157.5 135.5 623 43.1 105.4 136.5 165.1 172.6 189.2
DEEP Yr 177.71 212.05 229.52 Yr*2 *2) water. Mean Mean 
11
AND Station 175.3 286.7 215.7 25.0 22.0 23.2 Station 605.7 319.3 197.9 479.8 61.4 12.0 (Year pore 
* 
* of 
Yr 
Yr 1986 
liter
SURFACE August 
per 
N 
IN *1)and Hg-atrn 
= 
(Year units 
603 79.2 19.6 .2
CONCENTRATION 
153.6 198.4 206.3 213.9 85 74.1 155.4 200.6 219.9 189.8 985
Yr*2 Yr*2 201 
1 
Mean 1 Mean 
“ 
1 —— 
* 
»
3.4. AMMONIUM Station 266.6 374.4 245.8 194.9 173.5 Station 1 — — —-“ August concentration
1305.4 — 
Yr Yr for 
Table 
are 
Ammonium
1
1 29
23 
-
-
Depth nterval (cm) 7-8 8-9 9-10 Depth nterval (cm) -2-3 7-8 9-10 Data 
1
1 0S
02 
Appendix 3.1 
Bottom Water Dissolved Oxygen Concentration (Station 85) 

Sample Bottom Date Water DO (mg/1) 
Year I 
11/28/84 10.7 
1/23/85 12.0 
3/6/86 9.8 
4/3/85 11.0 
5/8/85 8.9 
6/5/85 7.2 
7/17/85 6.8 
8/14/85 7.1 
Year 2 
10/23/85 7.0 
12/4/85 9.8 
2/5/86 8.0 
4/9/86 6.4 
6/4/86 6.0 
8/6/86 5.9 
Dissolved concentration determined by Winkler method.
oxygen 
Appendix 3.2 
Percent Saturation of Dissolved Oxygen (bottom water of Station 85) 

Sample Date % Saturation 
Year 1 
11/28/84 110.5 
1/23/85 105.9 
3/6/85 103.2 
4/3/85 122.8 
5/8/85 110.0 
6/5/85 97.5 
7/17/85 93.0 
8/14/85 103.8 
Year 2 
10/23/85 97.1 
12/4/85 93.2 
2/5/86 96.0 
4/9/86 89.8 
6/4/86 85.5 
8/6/86 80.8 
“ 
h) 
per 145.3 69.7f26. 68.2 66.2 46.8 83.5 78.7 29,6 22.1 105.9 197.4 361.8 17,9±STD 
m2 
per 	198.4 311,0 201.7 167.5 123.8 106.0 176.4 217.6 131.8 149.6 211.1 259.9 412.3 150.6 
02 AVE 
(mg 
May], 
on 
0.52 0.25 0.09 0.24 0.24 0.17 0.30 0.28 0.1 0.08 0.38 0.70 1.29 0.06 pump* and 
Rate ±STD 1 (Apr mounted wiper 
2. pump
Experiments Respiration 
0.71 1.11 0.72 0.60 0.44 0.38 0.63 0.77 0.47 0.53 0.75 0.92 1.47 0.54 Rate h) 
per AVE 	windshield chambers: Katy.
Masterflex
1 
0.34 0.93 0.69 0.33 0.33 0.53 0.30 0.56 0.48 0.47 1.18 1.72 1.02 0.49
Chamber per Ch*2 winkler 	R/V
a 
by of
Respiration 	respiration
*B502 	—— 
0.64 0.65 0.28 0.20 0.88 0.67 0.36 0.51 0.46 0.38 0.47 0.58 	deck
an‘automobile
(mg — 	mixed 
Benthic Station Ch*1-winkler to 	the data).on 
1.07 1.28 0.82 0.81 0.71 0.40 0.70 1.09 0.57 0.62 0.62 0.68 2.92 by attached August],
electrode 	“ mixed mounted Cullen’s
3.3. 	follows: 
housing and 
as Jul, (see
Mar‘85], pump 
set10.7 12.0 9.8 11.0 8.9 7.2 6.8 7.1 7.0 9.8 8.0 6.4 6.0 5.9 tight
Appendix 	mixed [Jun,
(mg/1) 	Katy. data 
3.
not 
DO 	and water Masterflex
— 	0 4.4 1.5 7.1 2.6 9 5.4 62
3.6 6.1 68.3 21.4 78.4 	or Jan'65, and R/V
a 
in of
Turbidity (JTU) 	Hydrolab
mixed a 
mixing: deck by 
5.0 1.8 3.7 9.6 8.9 8.2
6.4 11.8 16.6 20.5 13.1 23.9 18.9 11.0 (Nov‘84, mounted no the Mixed fromSalinity (ppt) either 
. 
data
1 
*2. 
14.9 6.3 16.3 20.3 25.0 28.0 28.8 29.8 25.2 10.6 20.0 24,5 27.4 28.1 were # 
Temp CO 	Year Year 
Chambers Hydrographic
.* 
Sample Date 1 11/28/84 1/23/85 3/6/85 4/3/85 5/8/85 6/5/85 7/17/85 8/14/85 2 10/23/85 12/04/85 2/05/86 4/09/86 6/04/86 8/06/86
YEAR 	YEAR 
Appendix 3.4 Ammonium.concentrations of pore waters in sediments of the Lavaca Bay estuary. PortLavaca;AmmoniumConcentrationAnalyses 11/28/84 SedimentCoreSamples 

CORE *603 : 11 /84  
DILUTION FACTOR:  10  r  
DEPTH INTERVAL  
(cm)  3 Uu n  
A  B  NET AVE  A  B  AVE  ±ST0  
0-1  2.841  2.843  2.834  1706.63  1707.83  1707.23  0.85  
1  -2  0.331  2.843  1.579  194.58  1707.83  95120  1070.03  
2-3  0.303  2.843  1.565  177.71  1707.83  .942.^7  1081.96  
3-4  0.324  2.843  1.576  190.36  1707.83  '949.10  1073.01  
4-5  0.268  2.843  1.548  156.63  1707.83  93223  1096.87  
5-6  0.293  1.312  0.795  171.69  785.54  478.61  434.06  
6-7  0.262  0.98  0.613  153.01  585.54  369.28  305.84  
‘  
7-8  0.279  0.96  0.612  163.25  573.49  368.37  290.08  
8-9  0.319  0.969  0.636  187.35  578.92  383.13  276.88  
9-10  0.304  0.956  0.622  178.31  571.08  374.70  i 277.73  
i  *!  
i  CORE *85: 11/84  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  .nr\£An  jig aim rr  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  2.448  1.587  2.010  1469.88  951.20  1210.54  366.76  
1  -2  1.482  0.772  1.119  887.95  460.24  674.10  302.44  
2-3  0.726  0.633  0.672  432.53  376.51  404.52  39.62  
3-4  0.601  0.602  0.594  357.23  557.83  357.53  0.43  
4-5  0.762  0.739  0.743  454.22  440.36  447.29  9.80  
5-6  0,806  0.712  0.751  480.72  424.10  452.41  40.04  
6-7  0.795  0.653  0.716  474.10  388.55  431.33  60.49  
ir- CO  0.723  0.688  0.698  430.72  682.87  556.80  178.29  
ON1CO  0.778  0.762  0.762  463.86  454.22  • 459.04  6.82  
9-10  0.665  0.743  0.696  395.78  442.77  419.28  33.23  

Appendix 3.4 (Continued) 
PortLavaca:AmmoniumConcentrationAnalyses 11/28/S4 SedimentCoreSamples 

CORE  *65: 11/84  
DILUTION FACTOR:  10  
_  
DEPTH INTERVAL  
/ \ Lem;  duna  
A  B  NET AVE  A  B  AVE  ±STD  
0-t  1.518  0.543  1.023  909.64  322.29 •  615.96  415.32  
1 -2  1.504  1.667  1.578  901.20  999.40  950.30  69.43  
2-3  1.416  1.226  1.313  848.19  733.73  790.96,  80.93  
3-4  1.181  0.857  1.011  706.63  511.45  609.crf:  138.01  
4-5  0.644  0.538  0.583  383.13  319.28  35 i 20  45.15  
5-6  0.287  0.358  0.315  168.07  210.84  189.46  3024  
6-7  0.293  0.305  0.291  171.69  178.92  175.30  5.11  
7-8  0.198  0.243  0.213  114.46  141.57  128.01  19.17  
8-9  0.131  0.241  0.178  74.10  140.36  107.23  46.86  
1cr>  0  0.122  0.298  0.202  68.67  174.70  121.69  j .  74.97  
j  CORE *623: 11/84  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
kem;  .nr*£/in_UUD^U  dim M  
A  B  NET AVE  A  B  AVE  ±STD  
0-t  2.845  2.843  2.836  1709.04  1707.83  1708.43  0.85  
1-2’  1.829  0.984  1.399  1096.99  587.95  842.47  359.94  
2-3  1.062  1.466  1.256  634.94  878.31  756.63  172.09  
3-4  1.721  2.293  1.999  1031.93  1376.51  1204.22  243.65  
4-5  1.564  1.409  1.479  937.35  843.98  890.66  66.03  
5-6  1.026  1.207  1.109  613.25  722.29  667.77  77.10  
6-7  0.744  1 -436  1.082  443.37  860.24  651.81  294.77  
7-8  0.599  1.607  1.095  356.02  963.25  659.64  429.38  
¦ 8-9  0.628  1.334  0.973  373.49  798.80  586.14  300.73  
9-10  0.526  1.242  0.876  312.05  743.37  527.71  304.99  

Appendix  3.4 (Continued)  
Port Lavaca: AmmoniumConcentrationAnalyses  11 /28/84 SedimentCore Samples  
CORE «613;  11/84  
DILUTION FACTOR:  J0_  
DEPTH INTERVAL  
lemj  nr\r a o Ul/OtU  py  r.t dUII  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  2.841  2.844  2.835  1706.63  1708.43  1707.53  128  
1-2  1.962  1.638  1.792  1177.11  981.93  1079.52  138.01  
_  
2-3  2.264  1.367  1.808  1359.04  818.67  1088,86^  382.09  
3-4  1.514  1.343  1.421  907.23  804.22  855:72  72.84  
4-5  1.136  1,526  1.323  679.52  914.46  796.99  166.13  
5-6  1.1001  1.363  1.224  657.89  816.27  737.08  111.99  
6-7  1.1009  1.348  1.216  658.37  80723  732.80  10526  
7-8  1.159  1.053  1.098  693.37  629.52  661.45  45.15  
8-9  1.062  0.97  1.008  634.94  579.52  60723  39.19  
9-10  0.838  0.817  0.820  500.00  487.35  493.67  I 8.95  

Appendix 3.4 (Continued) 
PortLavaca: AmmoniumConcentrationAnalyses 1/23/S5SedimentCoreSamples 


CORE  “603:1/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  2.848  1.795  2.314  1710.84  1076.51  1393.67  448.54  
1 -2  1.096  1.325  1.203  655.42  793.37  724.40  97.55  
2-3  0.908  1.175  1.034  542.17  703.01  622^9  113.73  
3-4  1.237  0.718  0.970  740.36  427.71  584.04  221.08  
4-5  0.692  0.995  0.836  412.05  594.58  503.31  129.07  
5-6  0.849  0.843  0.838  506.63  503.01  504.82  2.56  
6-7  0.744  0.766  0.747  443.37  456.63  450.00  9.37  
7-8  0.928  0.911  0.912  554.22  543.98  549.10  7.24  
8-9  0.938  0.851  0.887  560.24  507.83  534.04  37.06  
9-10  0.892  0.678  0.777  532.53  403.61  468.07  L  91.16  
1  CORE **85: 1/85  
DILUTION FACTOR:  10  
_  
DEPTH INTERVAL  
/  \  
i>cmj  UUonU  '  Hg-aim iv  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.852  2.167  2.002  1110.84  1300.60  1205.72  134.18  
1 -2  0.765  1.149  0.949  456.02  687.35  571.69  163.57  
2-3  0.575  0.785  0.672  341.57  468.07  404.82  89.45  
3-4  0.393  0.981  0.679  231.93  586.14  409.04  250.47  
4-5  0.281  0.525  0.395  164.46  311.45  237.95  103.94  
5-6  0,365  0.348  0.349  215.06  204.82  209.94  7.24  
6-7  0.299  0.303  0.293  175.30  177.71  176.51  1.70  
7-8  0.256  0.468  0.354  149.40  277.11  213.25  90.31  
8-9  0.318  0.513  0.408  186.75  304.22  - 245.48  83.06  
9-10  0.378  0.544  0.453  222.89  322.89  272.89  70.71  

Appendix 3-4 (Continued) 
PortLavaca: AmmoniumConcentrationAnalyses t/23/85SedimentCoreSamples 

CORE  *65: 3/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  •UUoHU  pig-auTi iv  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.718  1.193  1.448  1030.12  713.86  871.99  223.63  
1 -2  0.225  1.436  0.823  130.72  860.24  495.48  515.85  
2-3  0.101  0.649  0.367  56.02  386.14  221 .Q8  233.43  
3-4  0.091  0.408  0.242  50.00  240.96  145.48  135.03  
4-5  0.805  0.184  0.487  480.12  106.02  293.07  264.53  
5-6  0.109  0.175  0.134  60.84  100.60  80.72  28.11  
6-7  0.09  0.143  0.109  49.40  81.33  65.36  22.58  
7-8  0.098  0.146  0.114  54.22  83.13  68.67  20.45  
8-9  0.102  0.12  0.103  56.63  67.47  62.05  7.67  
9-10  0.125  0.119  0.114  70.48  66.87  68.67  I  2.56  
i  CORE  *623:  1/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  UL>t>4U  (j.g  aim iv  
A  B  NET AVE  A  B  AVE  ±STD.  
0-1  «DIV/0!  -4.82  -4.82  -4.82  0.00  
1 -2  *DIV/0!  -4.82  -4.82  -4.82  0.00  
2-3  «DIV/0!  -4.82  -4.82  -4.82  0.00  
3-4  *DIV/0!  -4.82  -4.82  -4.82  0.00  
4-5  «DIV/OI  -4.82  -4.82  -4.82  0.00  
5-6  *DIV/0!  -4.82  -4.82  -4.82  0.00  
6-7  «DIV/0!  -4.82  -4.82  -4.82  0.00  
7-8  *DIV/0!  -4.82  -4.82  -4.82  0.00  
8-9  “DIV/0!  -4.82  -4.82  '  -4.82  0.00  
9-10  •01V/0!  -4.82  -4.82  -4.82  0.00  

Appendix 3-4 (Continued) 
PortLavaca: AmmoniumConcentrationAnalyses t/23/85SedimentCoreSamples 


CORE **613:1/85  
DILUTION FACTOR:  10  
r  
_  
DEPTH INTERVAL  
/ \ Lcrn;  .nr*/:anUUbnU  1 1 —  -A __ fL | dull IX  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.737  1.198  1.460  1041.57  716.87  879.22  229.60  
1 -2  0.932  1.191  1.054  556.63  712.65  634.64  110.33  
2-3  0.891  1.472  1.174  531.93  881.93  706.9J  247.49  
3-4  0.704  0.708  0.698  419.28  421.69  420.48  1.70  
4-5  0.912  0.528  0.712  544.58  313.25  428.92  163.57  
5-6  0.747  0.564  0.648  445.18  334.94  390.06  77.95  
6-7  0.661  0.607  0.626  393.37  360.84  377.11  23.00  
7-8  0.676 - 0.693  0.677  402.41  412.65  407.53  7.24  
8-9  0.559  0.682  0.613  331.93  406.02  368.98  52.39  
9-10  0.507  0.702  0.597  300.60  418.07  359.34  j_. 83.06  
j  CORE  **655:1/85  
DILUTION FACTOR;  10  
_  
DEPTH INTERVAL  
/ \ LCfifU  11 — [jlq  i aim m  
A  B  NET AVE  A  B  AVE  dhSTO  
0-1  2.848  2.840  1710.84  17(0.84  «DIV/0!  
1 -2  2.849  2.841  1711.45  1711.45  **DIV/0!  
2-3  0.586  0.479  0.525  1740.96  2837.35  2289.16  775.26  
3-4  2.849  0.056  1.445  1711.45  144.58  928.01  1107.94  
4-5  1.298  1.290  1295.44  1295.44  «DIV/0!  
5-6  1.605  1.597  962.05  962.05  **DIV/0!  
6-7  1.904  1.484  1.686  1142.17  889.16  1015.66  178.91  
7-8  0.52?  0.519  1563.25  1563.25  **DIV/0!  
8-9  «DIV/0!  *DIV/0!  «DIV/0!  
9-10  **DIV/0!  **DIV/0!  **DlV/0!  

3.4 (Continued) PortLavaca: AmmoniumConcentrationAnalyses t/2S/85SedimentCoreSamples 
Appendix 
CORE  “1505:  11/84  
DEPTH INTERVAL (cm)  DILUTION FACTOR: A B  10 NET AVE  A  B  o UII  e  AVE  ±STD  
0-1 1 -2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 01cr»  '  2.849 2.85 2.492 1.696 1.398 1.118 1.106 0.847 0.818 0.902  2.85 2.159 2.547 1.878 1.669 1.358 0.963 1.095 0.699 0.675  2.842 2.497 2.512 1.779 1.526 1.230 1.027 0.963 0.751 0.781  1711.45 1712.05 1496.39 1016.87 837.35 668.67 661.45 505.42 487.95 538.55  1712.05 1295.78 1529.52 1126.51 1000.60 81325 575.30 654.82 41627 401.81  1711.75 1503.92 1512,95 -1071.69 918.98 740.96 618.37 580.12 452.11 470.18  I  0.43 294.34 23.43 77.53 115.44 10223 60.91 105.64 50.69 96.69  
i  CORE “45:1/85  
DEPTH INTERVAL / \ LCfTfU  DILUTION FACTOR: nr\CAn A B  10 NET AVE  A  (Ay B  dunn  AVE  ±$TD  
0-1 1 -2 2-3 3-4 4-5 5-6 crs i -j 7-8 8-9 9-10  1,209 2.398 1.967 1.508 2.847  1.438 2.238  1.316 2.230 “DIV/O! 2.390 1.959 1.500 2.839 “DIV/O! “DIV/O? “DIV/0!  1808.73 1439.76 1180.12 903.61 2137.80  861.45 1343.37  1335.09 1343.37 “DIV/O! 1439.76 1180.12 903.61 2137.80 “DIV/O! .“DIV/O! “DIV/O!  669.83 “DIV/O! “DIV/O! “DIV/O! “DIV/O! “DIV/O! “DIV/O! “DIV/O! “DIV/O! “DIV/O!  

Appendix 3.4 (Continued) PortLivaoa:PoroVatorAmmoniumConcentration 2/6/85SedimentCoroSamples 
CORE *6033/85
: 
DILUTIONFACTOR; 10 
DEPTH INTERVAL 
-
/\ 
—
kcrru ¦UL'b'UJ-jxg aim rwi ox r ore wdier
A B NET AVE A B AVE ±STD 
0-1  2.541  2.793  2.659  1525.90  1677.71  1601.81  107.34  
1-2  1.917  1.716  1.809  1150.00  1028.92  1089.46  85.62  
_  
2-3  1  427  1.221  1.316  854.82  730.72  792.77  87.75  
_  
3-4  1.303  1.198  1.243  780.12  716.87  748/49  44.73  
,  
4-5  1.006  0.937  0.964  601.20  559.64  580.42  29.39  
5-6  0.982  0.889  0.928  586.75  530.72  558.73  39.62  
6-7  0.778  0.718  0.740  463.86  427.71  445.78  25.56  
_  
7-8  1.046  0.704  0.867  625.30  419.28  52229  145.68  
8-9  0.767  0.538  0.645  457.23  319.28  388.25  97.55  
9-10  __  0.618  0.706  0.654  367.47  420.48  395.98  j  37.49  

i¦ 
CORE *85: 3/85
i 
DILUTION FACTOR: 10 DEPTH INTERVAL 
/\ 
kcm; Ul/oHU aimluiot ior6 nai£r
JJLQ A B NET AVE A B AVE ±STD 
t/l. 
0-1 2.844 2.453 -2.641 1708.43 1472.89 1590.66 166.55 1 -2 1.414 1.551 1.475 846.99 929.52 888.25 58.36 2-3 0.473 0.741 0.599 280.12 441.57 360.84 114.16 3-4 0.427 0.798 0.605 252.41 364.16 158.03
475.90 
_ 
4-5 0.061 31.93 234.71
0.612 0.329 363.86 197.89 
5-6 0.756 0.475 0.607 450.60 280.12 365.36 120.55 6-7 0.543 0.557 0.542 322.29 330.72 326.51 5.96 
_ 
7-8 
0.91 
0.524 0.709 543.37 310.84 427.11 164.42 8-9 

1.079 
0.838 0.951 645.18 500.00 572.59 102.66 vjO 0 1.161 1.417 1.281 694.58 848.80 771.69 109.05


i1 
3.4 (Continued) Port Lavaoa: Poro V-ator AmmoniumConcentration 3/6/85SedimentCoro Samples 
Appendix 
CORE **63: 3/83  
DILUTION FACTOR:  10  
r  
DEPTH INTERVAL  
„„.  
(cm)  ¦Ul/t>4U­ yvy  duim/i  in rur c  novel  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  0.769  0.607  0.680  458.43  360.84  409.64  69.01  
1 -2  0.516  0.753  0.627  306.02  448.80  577.41  100.95  
2-3  0.243  0.334  0.281  141.57  196.39  168.98  38.76  
3-4  0.203  0.176  0.182  117.47  101.20  i.og.s^  11.50  
4-5  0.203  0.162  0.175  117.47  92.77  105.12  17.46  
5-6  0.137  0.383  0.252  77.71  225.90  151.81  104.79  
6-7  0.119  0.095  0.099  66.87  52.41  59.64  10.22  
7-8  0.117  0.122  0.112  65.66  68.67  67.17  2.13  
8-9  0.113  0.116  0.107  63.25  65.06  64.16  1.28  
9-10  0.113  0.105  63.25  0.00  0.00  .  0.00  
i  
i  CORE **623 :5/85  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
/ \ kcrru  .nr>£/<n  aim n/i oi roro  ifditf  
A  B  NET AVE  A  9  AVE  ±STD  
0-1  1.734  0.954  1.336  1039.76  569.88  804.82  332.25  
1 -2  1 -273  1.197  1.227  762.05  716.27  739.16  32.37  
2-3  0.915  1.015  0.957  546.39  606.63  576.51  42.60  
3-4  0.708  0.679  0.686  421.69  404.22  412.95  12.35  
4-5  0.564  0.619  0.584  334.94  368.07  351.51  23.43  
5-6  0.365  1.048  0.699  215.06  626.51  420.78  290.94  
6-7  0.318  0.538  0.420  186.75  319.28  253.01  93.71  
7-8  0.322  0.49  0.398  .  189.16  290.36  239.76  71.56  
8-9  0.295  0.446  0.363  172.89  263.86  218.37  64.32  
9-10  0.375  0.492  0.426  221.08  291.57  '256.33  49.84  

3.A PortLavaca: PoreViterAmmoniumConcentration 
Appendix (Continued) 
5/6/85SedimentCore Samples 
CORE **613: 3/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
/ \ LCfTU  1 | 1 ff /f • t f m jig-awn ix/i in rore w3t£T  *  
A  B  NET AVE  A  B  ¦AVE  i  ±STD  
0-1  1.434  1.628  1.523  859.04  975.90  917.47  82.64  
1  -2  1.154  1.616  1.377  690.36  968.67  829.52  196.80  
2-3  0.699  1.276  0.980  416.27  763.86  590.06  245.78  
3-4  0.742  1.104  0.915  442.17  660.24  551.20  15420  
4-5  0.781  1.116  0.941  465.66  667.47  566.57  142.70  
_  
5-6  0.847  1.356  1.094  505.42  812.05  658.73  '216.82  
_  
6-7  0.901  1.394  1.140  537.95  834.94  686.45  210.00  
7-8  0.873  1.134  0.996  521.08  678.31  599.70  111.18  
8-9  ...  >0.847  1.133  0.982  505.42  677.71  591.57  121.83  
_  
9-10!  0.641  1.035  0.830  381.33  618.67  500.00  167.83  

3.A (Continued) Port Lavaca: Pore Vater AmmoniumConcentration 3/6/85SedimentCore Samples 
Appendix 
CORE  *45 3/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
/ \ ».crn;  .nr\C/inUUb*tU  jig-dunim/ i ot 1 ore wdier  
A  B  NET AVE  A  B  • AVE t  ±STD  
0-1  1.535  2.395  1.957  919.88  1437.95  1178.92  366.33  
_  
1  -2  1.749  1.552  1.643  1048.80  930.12  989.46  83.92  
2-3  1.467  1.154  1.303  878.92  690.36  784.64  133.33  
3-4  1.779  1.429  1.596  1066.87  856.02  961.45  149.09  
4-5  2.846  2.838  1709.64  1709.64  «D1V/01  
5-6  2.847  2.197  2.514  1710.24  1318.67  1514.46  *276.88  
6-7  *DIV/0!  -4.82  -4.82  -4.82  0.00  
7-8 •  *DlV/0!  -4.82  -4.82  -4.82  0.00  
8-9  :  «DlV/0!  -4.82  -4.82  -4.82  0.00  
9 - 10'  *DIV/0!  -4.82  -4.82  -4.82  0.00  

3.A Port Lavaca; Pore Water AmmoniumConcentration 4/3/85 
Appendix (Continued) 
CORE_^6J03 : 4/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  r  
Ecmj  •UUMU ~ A B  n/ior i ore waier NET AVE A B AVE  ±STD  
0-1  1.573 1.076  1.317 942.77 643.37 793.07  211.71  
1 -2  1.124 0.852  0.980 672.29 508.43 590.36  115.86  
2-3  0.855 1.052  0.946 510.24 628.92 569.58  83.92  
3-4  0.826 0.969  0.890 492.77 578.92 535.84  60.91  
4-5  0.747 0.748  0.740 445.18 445.78 445.48  0.43  
5-6  0.643 0.716  0.672 382.53 426.51 404.52  31.10  
6-7  0.622 0.595  0.601 369.88 353.61 361.75  11.50  
7-8  0.619 0.674  0.639 368.07 401.20 384.64  23.43  
8-9  0.56 0.653  0.599 332.53 388.55 360.54  39.62  
9-10  0.643 0.586  . 0.607 382.53 348.19 365.36  l  24.28  
I '  
1  CORE *85: 4/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
/ \ Ecrn;  A B  lfHg dim lx/ 1 OT rO( £ if <ue( NET AVE A B AVE  ±STD  
0-1  1.382 1.696  1.531 827.71 1016.87 922.29  133.75  
1 -2  1.314 1.033  1.166 786.75 617.47 702.11  119.70  
2-3  0.582 0.402  0.484 345.78 237.35 291.57  76.67  
3-4  0.451 0.317  0.376 333.58 465.36 599.47  93.18  
4-5  0.295 0.329  0.304 172.89 193.37 183.13  14.48  
5-6  0.41 0.418  0.406 242.17 246.99 244.58  3.41  
6-7  0.431 0.278  0.347 254.82 162.65 208.73  65.17  
7-8  0.332 0.241  0.304 225.30 140.36 182.83  60.06  
8-9  0.284 0.225  0.247 166.27 130.72 148.49  25.13  
9-10  0.277 0.363  0.312 162.05 213.86 187.95  36.63  

Appendix 3.4 (Continued) 
PortLavaca: PoreVaterAmmoniumConcentration 4/3/85 


CORE **65:TTj  J  
DILUTION FACTOR:  10  *  
_  
DEPTH  INTERVAL  —•  
Ecm;  ¦Ul/tvHJ­ aim n/ 1 ox i oi e waior  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  0.062  0.643  0.345  32.53  382.53  207.53  247.49  
1 -2  1.093  1.012  1.045  653.61  604.82  62322  34.50  
2-3  1.351  1.436  1.386  809.04  860.24  834-64.  36.21  
3-4  0.974  0.659  0.809  581.93  392.17  437.05  134.18  
4-5  1.232  0.412  0.814  737.35  243.37  490.36  34929  
5-6  0.661  0.241  0.443  393.37  140.36  266.87  178.91  
6-7  0.709  0.211  0.452  422.29  122.29  272.29  212.13  
7-8  0.786  0.153  0.462  468.67  87.35  278.01  269.64  
8-9  0.219  0.158  0.181  127.11  90.36  108.73  25.98  
9-10  0.155  0.188  0.164  88.55  108.43  98.49  i.  14.06  

•>  *  
i  CORE  *623: 4/85  
DILUTION FACTOR:  10  
_  
DEPTH  INTERVAL  
/ \ kcm;  .nr\c AC\~  •atm in/i ot rore waier—  
A  B  NET AVE  A  B  AVE  ±STp.  
0-1  1.576  1.798  1.679  944.58  1078.31  1011.45  94.56  
1 -2  1.059  1.098  1.071  633.13  556.63  644.88  16.61  
‘  2-3  0.951  0.998  0.967  568.07  596.39  582.23  20.02  
3-4  0.62  0,904  0.754  921.69  539.76  730.72  270.06  
4-5  0.728  0.834  0.773  433.73  497.59  465.66  45.15  
5-6  0.927  0.871  0.891  553.61  519.88  536.75  23.85  
6-7  6.957  5.694  0.818  571.69  413.25  492.47  112.03  
7-8  0.284  0.563  0.416  831.33  334.34  582.83  351.42  
CO i  vO  0.353  0.767  0.552  1039.16  457.23  •748.19  411.49  
vjO I  o  0.594  0.586  -4.82  353.01  174.10  253.02  

DEPTH INTERVAL (cm) 
0-1 1 -2 2-3 
3-4 
4-5 5-6 6-7 
7-8 8-9 9-10 
i 
DEPTH INTERVAL (cm) 
0-1 1 -2 2-3 
3-4 4-5 5-6 6-7 7-8 8-9 
9-10 
3.A (Continued)
Appendix 
PortLavaca: PoroValorAmmoniumConoontration 4/3/85 
CORE *613:4/85 
D LOTION FACTOR: 10 
r.i/IUUb4U dUIIM/IUI 1 Ul C «<HCI 
A B NETAVE A B AVE 
1.567 0.983 1.267 939.16 587.35 763.25 
0.916 0.892 0.896 546.99 532.53 539.76 
0.873 0.898 0.878 521.08 536.14 528.6-4 
0.712 0.767 0.732 424.10 457.23 440.66 
0.864 0.604 0.726 515.66 359.04 437.35 
0.823 0.682 0.745 490.96 406.02 448.49 
0.497 0.761 0.621 294.58 453.61 374.10 
0.509 0.721 0.607 301.81 429.52 365.66 
0.571 0.701 0.628 339.16 417.47 378.31 
0.746 0.556 0.643 444.58 330.12 387.35 
CORE *633:4/85 
DILUTION FACTOR: 10 
. 
—	—
UL>d4U	¦atm N/l ot* Porf Vater
A B NETAVE A B AVE 
1.794 
1.786 	1793.53 1793.53 

2.405 
2.397 	1443.98 1443.98 


1.263 	1.255 756.02 756.02 
0.709 0.147 0.420 422.29 4186.75 2304.52 
0.706 	0.698 420.48 420.48 
0.848 	
0.840 506.02 506.02 

1.152 	
1.144 689.16 689.16 

2.259 	
2.251 1356.02 1356.02 


1.658 	1.650 993.98 •993.98 *DIV/0! *DIV/0! 
±STD 
248.77 
10.22 
10.65 
23.43 
110.75 
60.06 
112.46 
90.31 
55.38 
L 80.93 
±STD: 
«DIV/0! 
*DIV/0! 
*DIV/0! 
2661.87 *DIV/0! *DIV/0! «DIV/0! 
•DIV/0! 
*DIV/0! «DIV/0! 
Appendix 3.4 (Continued) 
PortLavaca: PoroVatorAmmoniumConcentration 5/8/85SedimentCoroSamples 


CORE  *603; 5/85  
DILUTION FACTOR:  10  
r  
DEPTH INTERVAL  
/  \  .nrv£/mUL/oHU —  P9  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.176  1.224  1.192  703.61  732.53  718.07  20.45  
1 -2  0.842  1.282  1.054  502.41  767.47  634.94  187.43  
2-3  0.663  0.762  0.705  394.58  454.22  424.40  42.17  
3-4  0.362  0.487  0.417  213.25  288.55  ,250.90  53.25  
4-5  0.323  0.423  0.365  189.76  250.00  219.88  42.60  
5-6  0.431  0.464  0.440  254.82  274.70  264.76  14.06  
6-7  0.349  0.429  0.381  205.42  253.61  229.52  34.08  
7-8  0.326  0.404  0.357  191.57  238.55  215.06  33.23  
8-9  0.401  0.426  0.406  236.75  251.81  244.28  10.65  
9-10  0.447  0.395  0.413  264.46  233.13  248.80  j  22.15  
j  CORE  *85: 5/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
/  \  UL/oHU  1. 1 /i .r o dun m/ i vi rur v  ndi.fr  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  0.081  1.099  0.582  43.98  657.23  350.60  433.64  
1  -2  0.021  0.211  0.108  7.83  122.29  65.06  80.93  
2-3  0.575  0.936  0.748  341.57  559.04  450.50  153.77  
3-4  0.103  0.097  0.092  57.23  53.61  55.42  2.56  
4-5  0.131  0.192  0.154  74.10  110.84  92.47  25.98  
5-6  0.293  0.045  0.161  171.69  22.29  96.99  105.64  
6-7  0.207  0.215  0.203  119.88  124.70  122.29  3.41  
7-8  0.154  0.123  0.131  87.95  69.28  78.61  13.21  
8-9  0.188  0.178  0.175  103.43  102.41  105.42  4.26  
9-10  0.251  0.154  0.195  146.39  87.95  117.17  41.32  

Appendix 3.A (Continued) 
PortLivaoa: Poro AmmoniumConcentration 5/8/85 

CORE *65: 5/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  UDo'HU  ~  aim vif 1 oi rore  waier  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.257  0.546  0.894  752.41  324.10  538.25  302.86  
1 -2  0.681  1.221  0.943  405.42  730.72  568.07  230.02  
2-3  0.358  0.775  0.559  210.84  462.05  336.45  177.63  
3-4  0.223  0.469  0.338  129.52  277.71  203.6*1  104.79  
4-5  0.378  0.259  0.311  222.89  151.20  187.05  50.69  
5-6  0.254  0.165  0.202  148.19  94.58  121.39  37.91  
6-7  0.122  0.149  0.128  68.67  84.94  76.81  11.50  
7-8  0.095  0.108  0.094  52.41  60.24  56.33  5.54  
8-9  0.102  0.101  0.094  ‘56.63  56.02  56.33  0.43  
9-10  0.076  0.092  0.076  40.96  50.60  45.78  j  6.82  
t  
CORE  *623 : 5/85  
I  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
/ \ Lem;  .nru:/<n.UDtrHJ  jig-dun lx/1 oi i ore Vdier­"  
A  B  NET  AVE  A  B  AVE  ±STD  
0-1  0.627  0.828  0.720  372.89  493.98  433.43  85.62  
1 -2  0.794  0.971  0.875  473.49  580.12  526.81  75.40  
2-3  0.816  0.732  0.766  486.75  436.14  461.45  35.78  
3-4  0.793  0.551  0.664  472.89  327.11  400.00  103.08  
4-5  0.507  0.501  0.496  300.60  296.99  298.80  2.56  
5-6  0.336  0.569  0.445  197.59  537.95  267.77  99.25  
6-7  0.344  0.406  0.367  202.41  239.76  221.08  26.41  
-j i  CO  0.512  0.385  0.441  303.61  227.11  265.36  54.10  
8-9  0.513  0.322  0.410  304.22  189.16  246.69  81.36  
1  O  0.647  0.237  0.454  384.94  137.95  261.45  174.65  

Appendix 3.A (Continued) 
PortLavaca: PoreViterAmmoniumConcentration 5/8/85 

CORE “613:5/85 
•  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  'UL/onU  . r.i Ai t ouim/iuirun: k<su:i  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  0.696  1.059  0.870  414.46  633.13  523.80  154.63  
1  -2  0.629  0.736  0.675  374.10  438.55  406.33  45.58  
2-3  0.591  0.603  0.589  351.20  358.43  354.82.  5.11  
3-4  0.547  0.702  0.617  324.70  418.07  371.39*  66.03  
4-5  0.463  0.572  0.510  274.10  339.76  306.93  46.43  
5-6  0.544  0.563  0.546  322.89  334.34  328.61  8.09  
6-7  0.411  0.52  0.458  242.77  308.43  275.60  46.43  
7-8  0.378  0.556  0.459  222.89  330.12  276.51  75.82  
8-9  0.56  0.46  0.502  332.53  272.29  302.41  42.60  
9-10  0.42  0.557  0.481  248.19  330.72  289.46  :  58.36  
CORE *633; 5/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  ix/iot rore water —  
A  B  NET AVE  A  B  AVE  ±STD  
4 •K .  
0-1  «DIV/0!  «DIV/0!  *DIV/0!  
1 -2  *DIV/0!  *DIV/0!  *DIV/0!  
2-3  0.394  0.386  2325.30  2325.30  «DIV/0!  
3-4  1.648  1.640  987.95  987.95  *DIV/0!  
4-5  «DIV/01  *DlV/0!  «DIV/0!  
5-6  0.817  0.809  1218.37  1218.37  *DIV/0!  
6-7  «DIV/0!  *DIV/0!  «DIV/OI  
7-8  *DIV/0!  *DIV/0!  *DIV/0!  
8-9  *DlV/0!  *DlV/0!  *DIV/0!  
9-10  *DIV/0!  *DIV/0!  *DIV/0!  

Appendix  3.4 (Continued)  
Port Lavaoa:  Poro Vator AmmoniumConcentration  6/5/85  
CORE *603;6/85  
DILUTION FACTOR;  10  
DEPTH INTERVAL  r  
/ \Lem;  UUonU  **  jig aim lx/ 1 oi t ore  w<*ler—  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  0.482  0.163  0.315  285.54  233.43  259.49  36.85  
1 -2  0.257  0.154  0.188  150.00  189.76  169.88  28.11  
2-3  0.335  0.16  0.240  196.99  228.92  212.95  22.58  
3-4  0.402  0.178  0.282  237.35  256.02  24^69  13.21  
4-5  0.132  0.133  0.125  74.70  188.25  •131.48  80.29  
5-6  0.152  0.043  0.090  86.75  52.71  69.73  24.07  
6-7  0.228  0.094  0.153  132.53  129.52  131.02  2.13  
7-8  0.176  0.154  0.157  101.20  219.88  160.54  83.92  
8-9  0.445  0.157  0.293  263.25  224.40  243.83  27.47  
9-10  0.401  0.106  0.246  236.75  147.59  192.17  63.04  
i  
'  
i  
CORE *85; 6/85  
|  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
/ \ Lem;  - ¦atm n/i ot Fore water  ¦  
A  B  NET  AVE  A  B  AVE  ±STD  
• 4 « .  
0-1  0.284  0.523  0.396  166.27  285.16  225.71  84.07  
1 -2  6.179  0.256  0.210  103.01  138.46  120.74  25.07  
2-3  0.106  0.382  0.236  59.04  207.69  133.36  105.12  
3-4  0.075  0.322  0.191  40.36  174.73  107.54  95.01  
4-5  0.236  0.277  0.249  137.35  150.00  143.67  8.95  
5-6  0.292  0.269  0.273  171.08  145.60  158.34  18.02  
6-7  0.288  0.251  0.262  168.67  135.71  152.19  23.31  
7-8  0.016  0.193  0.097  4.82  103.85  54.33  70.02  
8-9  0.179  0.171  103.01  103.01  8DIV/0!  
9-10  0.254  0.246  148.19  •  148.19  "DIV/O!  

CORE *65: 6/85 
Appendix 3.4 (Continued) PortLavaca: PoreVater AmmoniumConcentration C/5/85 

DILUTION FACTOR;  10  
DEPTH INTERVAL  
r  
'i1cm;  'UL'bXU  ~  dimm/1 oi roro Wdicr  
A  B  NET AVE  A  B  AVE  ±£TD - 
0-1  1.063  0.278  0.663  635.54  406.63  521.08  161.87  
1 -2  0.066  0.123  0.087  34.94  173.19  104.07  97.76  
2-3  0.18  0.038  0.101  103.61  45.18  74.40  41.32  
3-4  0.036  0.039  0.030  16.87  46.69  •  31.7£  21.09  
4-5  0.035  0.048  0.034  16.27  6024  h  3825  31.10  
5-6  0.07  0.026  0.040  37.35  27.11  3223  724  
6-7  0.062  0.022  0.034  32.53  21.08  26.81  8.09  
7-8  0.055  0.024  0.032  28.31  24.10  26.20  2.98  
8-9  0.036  0.025  0.023  16.87  25.60  2123  6.18  
vjO 1  0  0.171  0.029  0.092  98.19  31.63  64.91  47.07  
! 1  
1  
i  ¦  
CORE *625 :6/85  
i  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
/  \  
icrn;  UUbMU  p.g  <iini lx/1 oi rore  waier  
A  B  NET  AVE  A  B  AVE  ±STD  
0-t  0.037  0.032  0.027  17.47  14.46  15.96  2.13  
1 -2  0.388  0.017  0.195  228.92  5.42  117.17  158.03  
K)I(N  0.026  0.09  0.050  10.84  49.40  30.12  27.26  
3-4  0.031  0.043  0.029  13.86  21.08  17.47  5.11  
4-5  0.022  0.026  0.016  8.43  10.84  9.64  1.70  
5-6  0.015  0.552  0.276  4.22  327.71  165.96  228.74  
6-7  0.098  0.069  0.076  54.22  36.75  45.48  12.35  
CO1r­ 0.189  0.125  0.149  109.04  70.48  89.76  27.26  
i  1  
8-9  0.168  0.02  0.086  96.39  723  51.81  63.04  
9-10  0.103  0.015  0.051  57.23  4.22  30.72 .  37.49  

Appendix Port Lavaca:  3.A (Continued) Pore Water AmmoniumConcentration  6/5/85  
CORE *613: 6/85  
DEPTH INTERVAL  DLOTION FACTOR:  10  
EccrU  A  'UDbHU B  NET AVE  _  A  -aim n/ioi r ore waier B "" AVE  ±£TD  
0-1 1 -2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10  1.365 1.173 0.802 0.877 0.901 0.661 0.99 1.026 0.486 0.647  0.904 1.324 1.147 0.406 0.383 0.304 0.552 0.203 0.197 0.04  1.127 1.241 0.967 0.634 0.634 0.475 0.763 0.607 0.334 0.336  817.47 701.81 478.31 523.49 537.95 393.37 591.57 613.25 287.95 384.94  539.76 792.77 686.14 239.76 225.90 178.31 327.71 117.47 113.86 19.28  678.61 747.29 582.23 381.63 ; 381.93 •285.84 459.64 365.36 200.90 202.11  196.37 64.32 146.96 200.63 220.65 152.07 186.57 350.57 123.10 258.56  
i  
l  CORE *635: 6/85  
| DEPTH INTERVAL / \ vcm;  DILUTION FACTOR: Ul/DHU A B  10 NET AVE  A  a a > P-g ¦aim lx /1 oi rore water B AVE  ¦  ±STD  
0-1 1 -2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10  0.046 0.127 0.128 6.028 0.078  0.033 0.072 0.022 0.069 0.192  0.032 0.092 0.014 0.061 #DlV/0! 0.152 0.020 0.070 «DIV/01 **DIV/0!  114.46 358.43 722.89 12.05 105.42  18.83 385.54 84.34 73.49 110.84  66.64 371.99 84.34 73.49 *DIV/0! 416.87 12.05 105.42 «DIV/0! «DIV/0!  67.62 19.17 «DlV/0! *DIV/0! °DIV/0! 432.78 #DIV/0! **DIV/0! «DIV/OI “DIV/O!  

Appendix 3.4 (Continued) 
PortLavaca: PoreWaterAmmoniumConcentration 6/5/85 

CORE  *45: 6/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  ¦UDMU  - - - -jig  atm K/i ot rore water  
A  B  NETAVE  A  B  . AVE  ±STD  
.¦  v  
0-1  0.108  0.494  0.293  60.24  292.77  176.51  164.42  
1 -2  *DIV/0!  *DIV/0!  *DIV/0!  
2-3  «DIV/0!  «DIV/0!  «DIV/0!  
3-4  *DIV/0!  «DIV/0!  *DIV/0!  
4-5  #DIV/0!  «DIV/0!  *DIV/0!  
5-6  *DIV/0!  *DIV/0!  *DIV/0!  
6-7  «DlV/0!  ttDIV/0!  «DIV/0!  
7-8  *0IV/0!  *DIV/0!  *0IV/0!  
8-9  «DIV/0l  «DIV/0!  #DIV/0!  
9-10  0.091  0.083  50.00  50.00  *DIV/0!  

Appendix 3.A (Continued) 
Port Poro V-ator AmmoniumConoontr-ation—7/17/85 
CORE *603: 7/85  .  
DILUTION FACTOR:  10  r  
DEPTH INTERVAL  
(cm)  ¦UUt>HU  jjlq  aim in/1 oi [ ore water—  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.268  1.349  1.301  759.04  807.83  783.43  34.50  
1 -2  0.854  0.829  0.834  509.64  494.58  502,11  10.65  
2-3  0.832  0.925  0.871  496.39  552.41  '  52^.40  39.62  
3-4  0.874  0.743  0.801  521.69  442.77  482.23  55.80  
4-5  0.708  0.782  0.737  421.69  466.27  443.98  31.52  
5-6  0.562  0.829  0.688  333.75  494.58  414.16  113.73  
6-7  0.634  0.595  0.607  377.11  353.61  365.36  16.61  
7-8  0.627  0.546  0.579  372.89  324.10  348.49  34.50  
8-9  0.496  0.478  0.479  293.98  283.13  288.55  :  7.67  
9-10  0.472  0.443  0.450  279.52  262.05  270.78  ‘  12.35  

i  
CORE *85: 7/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  UUd4U  — jig 3unix/1 oi rore Wdicr —  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  0.842  0.975  0.901  502.41  582.53  542.47  56.65  
1 -2  0.622  0.767  0.687  369.88  457.23  413.55  61.77  
2-3  0.544  0.882  0.705  322.89  526.51  424.70  143.98  
3-4  0.443  0.664  0.547  26323  395.18  329.22  93.29  
4-5  0.499  0.58  0.532  295.78  344.58  320.18  34.50  
5-6  0.467  0.469  0.460  276.51  277.71  277.11  0.85  
6-7  0.327  0.449  0.380  192.17  265.66  228.92  51.97  
7-8  0.284  0.472  0.370  166.27  279.52  222.89  80.08  
CO i  \0  0.332  0.408  0.362  195.18  240.96  218.07  32.37  
9-10  *DIV/0!  -4.82  -4.82  -4.82  0.00  

3.4 (Continued)
Appendix 
PortLavaca: PoreViterAmmoniumConcentration—7/17/85 
CORE *65: 7/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  -0D540­ <Ulll iw i  i vi  ii  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  0.762  0.987  0.867  454.22  589.76  521.99  95.84  
1 -2  0.661  0.929  0.787  393.37  554.82  .  .47^.10  114.16  
2-3  0.567  0.621  0.586  336.75  369.28 •,  ..353.01  23.00  
3-4  0.403  0.611  0.499  237.95  363.25  300.60  88.60  
4-5  0.432  0.959  0.688  255.42  572.89  414.16  224.49  
5-6  0.211  0.976  0.586  122.29  583.13  352.71  325.87  
6-7  0.219  0.628  0.416  127.11  373.49  250.30  174.22  
7-8  0.171  0.799  0.477  98.19  476.51  287.35  267.51  
8-9  0.013  0.508  0.253  3.01  301.20  152.11  i.  210.85  
•9-10  0.129  0.768  0.441  72.89  457.83  265.36  272.19  
i  
CORE  “623:7/85  
DILUTION FACTOR:  10_  
DEPTH INTERVAL  
(cm)  UD64U  “  *— dun  hi /i « f lu I vi 1 vi  c  noun  i« I •  
A  B  NET AVE  A  B  AVE  ±STD  
0 -1  1.257  1.558  1.400  752.41  933.73  843.07  128.22  
1-2  0.967  0.982  0.967  577.71  586.75  582.23  6.39  
2-3  0.711  0.839  0.767  423.49  500.60  462.05  54.52  
3-4  0.63  0.476  0.545  374.70  281.93  328.31  65.60  
4-5  0.572  0.506  0.531  339.76  300.00  319.88  28.11  
5-6  0.346  0.394  0.362  203.61  232.53  218.07  20.45  
6-7  0.379  0.4  0.382  223.49  236.14  229.82  8.95  
ir- CO  0.314  0.338  0.318  184.34  198.80  191.57  10.22  
.  
8-9  0.288  0.348  0.310  168.67  204.82  186.75  25.56  
9-10  0.202  0.267  0.227  116.87  156.02  136.45  27.69  

Appendix 3.A (Continued) 
PortLavaca: PoreWaterAmmoniumConcentration—7/17/85 

CORE  *613 7/85  - 
<•  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
/„ -s Ccmj  *UL>o4U  ~  <iuu rw i ui ruic w <n.n  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.276  1.025  1.143  763.86  612.65  688.25  106.92  
1 -2  0.947  0.872  0.902  565.66  520.48  543.07.  31.95  
2-2  0.957  0.725  0.833  571.69  431.93  501.8f  98.82  
3-4  0.648  0.609  0.621  385.54  362.05  373.80  16.61  
4-5  0.546  0.797  0.664  324.10  475.30  399.70  106.92  
5-6  0.521  0.666  0.586  309.04  396.39  352.71  61.77  
6-7  0.459  0.616  0.530  271.69  366.27  318.98  66.88  
7-8  0.395  0.524  0.452  233.13  310.84  271.99  54.95  
8-9  0.409  0.609  0.501  241.57  362.05  301.81  j  85.19  
9-10  0.448  .0.496  0.464  265.06  293.98  279.52  v  20.45  
¦f  
i  
CORE *633; 7/85  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
/  \  
UUdmU  atm N/1 oi rore water- 
A  B  NET AVE  A  B  AVE  ±STD‘'  
0-1  0.23  0.222  6686.75  6686.75  *DIV/0!  
1 -2  *DIV/0!  *0IV/0!  8DIV/0!  
2-3  0.977  0.969  583.73  583.73  8DlV/0!  
3-4  0.165  0.157  236.45  236.45  *PIV/0!  
4-5  1.032  1.024  6168.67  6168.67  *DIV/0!  
5-6  0.898  0.923  0.903  536.14  689.01  612.58  108.09  
6-7  ...0.852  0.371  0.604  508.43  546.69  527.56  27.05  
7-8  0.709  0.492  0.593  422.29  291.57  356.93  92.44  
8-9  0.818  0.810  609.94  609.94  *DIV/0!  
9-10  *DIV/0!  *DlV/0!  *0IV/0!  

Appendix 3.A (Continued) 
PortLavaoa: PoreWater AmmoniumConcentration—7/17/85 

CORE  *45: 7/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  .nrvC/4n_  jJig-aun ivl ox rOr6  wax^r — 1  
A  B  NET AVE  A  B  AVE*  ±STD  
0-1  1.132  0.924  1.020  677.11  551.81  614.46  88.60  
1 -2  *DIV/01  *DIV/0!  *DIV/OI  
2-3  0.648  0.640  385.54  385.54  *DIV/0!  
3-4  0.584  0.576  867.47  867.47  «DIV/0!  
4-5  *DIV/0!  *DlV/0!  j *DIV/0!  
5-6  ¦  *D1V/0I  *DIV/0!  *DIV/0!  
6-7'  *DIV/0!  *DIV/0!  «DIV/0!  
7-8  *DJV/0!  “DIV/O!  «DIV/0!  
8-9)  *DIV/0?  **0 IV/O!  *DIV/0!  
9-10  *DIV/OI  *DIV/0!  *DIV/0!  

(Continued)
Appendix 3.4 
PoreWaterAmmoniumConcentration 8/14/85SedimentCoreSamplesPort Lavaca: 
CORE *603 ; 8/85 
DILUTION FACTOR: 10 
r 
DEPTH INTERVAL -¦ 
.\ 
—
kCITlj Hg-aimn/ioi r or6 Yraier-
A B NET AVE A B AVE ±STD 
0-1 2.845 1.505 2.167 1709.04 901.81 1305.42 570.80 
1 -2 0.219 0.682 0.443 127.11 406.02 266.57 197.22 2-3 0.561 0.698 0.622 333.13 415.66 • ;37j4.40 58.36 3-4 1.088 1.124 1.098 650.60 672.29 -.661.45 15.33 4-5 0.776 0.922 0.841 462.65 550.60 506.63 62.19 
5-6 0.286 0.816 0.543 167.47 486.75 327.11 225.76 6-7 0.327 0.754 0.533 192.17 449.40 320.78 181.89 7-8 0.236 0.596 0.403 137.35 354-22 245.78 153.35 8-9 0.256 0.407 0.324 149.40 240.36 194.88 64.32 
9-10 JDL303 0.289 0.288 177.71 169.28 173.49 ' 5.96 
i 
CORE *85; 8/85
i 
DILUTION FACTOR; 10 DEPTH INTERVAL 
/\ 
*
kcm; UUoHU Pore water A B NET AVE A B AVE iSTD 
0-1 *DIV/0! 1 2 *DIV/0!
-
2-3 *DIV/0! 3-4 *DIV/0! 4-5 *DlV/0! 5-6 *DIV/0! 
6-7 *DIV/0! 7-8 *DIV/0! CO OS
I 
*DIV/0! 9-10 *DIV/0! 
Appendix 3.4 (Continued) PortLavaca: PoreVatorAmmoniumConcentration 8/14/85SedimentCoreSamples 
CORE *63: 8/83 
DILUTIONFACTOR: 10 
DEPTH INTERVAL 
-
—
Ecmj •UDb4U ""W“3im ix/ 1 oi r ore « aier” 
A B NET AVE A B AVE ±STD 
0-1  0.49  0.108  0.291  290.36  60.24  175.30  162.72  
1  -2  0.484  0.476  286.75  286.75  «0IV/0!  
2-3  0.304  0.428  0.358  178.31  253.01  .215.66  52.82  
3-4  0.217  0.195  0.198  125.90  112.65  Ji;9.28  9.37  
4-5  0.089  0.319  0.196  48.80  187.35  118.07  97.97  
5-6  0.027  0.123  0.067  11.45  69.28  40.36  40.89  
6-7  0.073  0.065  39.16  39.16  «DIV/0!  
7-8  0.032  0.067  0.042  14.46  35.54  25.00  14.91  
8-9  0.023  0.066  0.037  9.04  34.94  21.99  18.32  
9-10  0.058  0.035  0.039  30.12  1627  23.19  j  9.80  

1 
CORE *623:8/85
1 
DILUTION FACTOR: 10 DEPTH INTERVAL 
/\ i»i
.nPk£/*n p
Lcmj UDb'xU ¦dim ix/ 1 ox rori? Yr^iei 
±STDA B NETAVE A B AVE 
0-1 0.752 1.275 1.006 448.19 763.25 605.72 222.78 
-
1 2 0.588 0.488 0.530 349.40 289.16 31928 42.60 2-3 0.557 0.116 0.329 330.72 65.06 197.89 187.85 3-4 0.056 0.067 0.054 28.92 35.54 32.23 4.69 4-5 0.91 0.982 0.938 543.37 586.75 565.06 30.67 5-6 0.037 0.076 0.049 17.47 40.96 29.22 
16.61 6-7 0.031 0.057 0.036 13.86 29.52 .21.69 11.08 7-8 0.013 1.596 0.797 3.01 956.63 479.82 674.31 
8-9 0.098 0.122 0.102 54.22 68.67 61.45 1022 9-10 0.035 0.021 0.020 16.27 7.83 12.05 5.96 
3.A (Continued) PortLavaca:PoreVaterAmmoniumConcentration8/14/85SedimentCoreSamples 
Appendix 
CORE *613 : 8/85  
DILUTION FACTOR:  10  r  
DEPTH INTERVAL  
.  \  
kcm;  <jum n/iui rurc  n<n.ei  
A  B  NET AVE  A  B  AVE  ±STD  
0-1  1.467  1.214  1.333  878.92  726.51  802.71  107.77  
1 -2  1.831  0.626  1.221  1098.19  372.29  735.24  513.29  
2-3  0.476  0.07  0.265  281.93  37.35  ;15?.6f :  172.94  
3-4  0.351  0.657  0.496  206.63  390.96  298.80'  130.35  
4-5  0.804  0.812  0.800  479.52  484.34  481.93  3.41  
5-6  0.656  0.631  0.636  390.36  375.30  382.83  10.65  
6-7  0.721  0.558  0.632  429.52  331.33  380.42  69.43  
7-8  0.577  0.648  0.605  342.77  385.54  364.16  30.24  
8-9  0.614  0.606  365.06  365.06  *DIV/0!  
9-10  0.952  0.487  0.712  568.67  288.55  428.61  LI98.08  
i  *  
j  *  
j  CORE  *633: 8/85  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
/  s  .r\r\£An  ml ot rot e Vi ator  
A  B  NET AVE  A  B  AVE  ±ST.p.  
0-1  2.845  2.848  •  2.839  1709.04  1710.84  1709.94  1.28  
1 -2  2.85  2.842  1712.05  1712.05  *DIV/0!  
2-3  2.851  2.843  1712.65  1712.65  *DIV/0!  
3-4  1.255  2.017  1.627  750.00  1210.24  980.12  325.44  
4-5  6.0i  1.876  0.935  1.20  1125.30  563.25  794.86  
5-6  0.877  0.897  0.879  523.49  535.54  529.52  8.52  
6-7  0.72  0.712  428.92  428.92  *DIV/0!  
ir- CO  0.91  0.535  0.715  543.37  317.47  430.42  159.74  
i  
8-9  0.982  0.302  0.634  586.75  177.11  381.93  289.66  
9-10  *DIV/0!  *DIV/0!  *DIV/0!  

3.4
Appendix (Continued) Appendix 3.4 (Continued) 
CORE *603: 10/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  00640-­ -ug-atm  N/l of Pore Water-­ 
A  8  NET AYE  A  B  AYE  ±STD  
0-1  0.291  0.385  0.330  170.48  227.1 1  198.80  40.04  
t  -2  0.331  0.399  0.357  194.58  235.54  215.06  28.97  
2-3  0.366  0.428  0.389  215.66  253.01  234.34  26.41  
3-4  0.411  0.431  0.413  242.77  254.82  248.80  8.52  
4-5  0.436  0.397  0.409  257.83  234.34  246.08  16.61  
5-6  0.448  0.456  0.444  265.06  269.88  267.47  3.41  
6-7  0.498  0.482  0.482  295.18  285.54  290.36  6.82  
7-8  0.524  0.562  0.535  310.84  333.73  322.29  16.19  
8-9  0.557  0.546  0.544  330.72  324.10  327.41  4.69  
9-10  0.575  -­ 0.567  341.57  341.57  
CORE *85: 10/85  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  00640­¦  -Mg-atm N/l ofPore Water-­ 
A  B  NET AYE  A  B  AYE  ±STD  
0-1  0.275  0.134  0.197  160.84  75.90  118.37  60.06  
1  -2  0.323  0.106  0.207  189.76  59.04  124.40  92.44  
2-3  0.361  0.127  0.236  212.65  71.69  142.17  99.68  
3-4  0.307  0.148  0.220  180.12  84.34  132.23  67.73  
4-5  0.294  0.158  0.218  172.29  90.36  131.33  57.93  
5-6  0.293  0.182  0.230  171.69  104.82  138.25  47.28  
6-7  0.263  0.207  0.227  153.61  119.88  136.75  23.85  
7-8  0.293  0.216  0.247  171.69  125.30  148.49  32.80  
8-9  0.279  0.235  0.249  163.25  136.75  150.00  18.74  
9-10  0.286  0.244  0.257  167.47  142.17  154.82  17.89  

CORE *65: 10/85
„ 
DILUTION FACTOR; 10 )EPTH INTERVAL (cm) 00640-• -ug-atm N/l of Pore Water-­
—
A B NET AVE A B AYE ±STD 
0-1  0.272  0.269  0.263  159.04  157.23  158.13  1.28  
1 -2  0.245  0.297  0.263  142.77  174.10  158.43  22.15  
2-3  0.244  0.279  0.254  142.17  163.25  152.71  14.91  
3-4  0.245  0.186  0.208  142.77  178.75  160.76  25.44  
4­5  0.223  0.218  0.213  129.52  126.51  128.01  2.13  
5-6  0.163  0.139  0.143  1.52  78.92  40.22  54.73  
6-7  0.036  -­ 0.028  168.67  168.67  
7-8  -­ -­ -­ 
8-9  0.245  0.103  0.166  142.77  143.07  142.92  0.21  
9-10  0.371  0.155  0.255  218.67  88.55  153.61  92.01  

CORE *623; 10/85 
DILUTION FACTOR; 10 )£PTH INTERVAL (cm) 0D640---ug-atm N/l of Pore Water-­
——
A B NET AYE A B AVE ±STD 
0-1 0.239 0.328 0.276 139.16 192.77 165.96 37.91 
-
1 2 0.184 0.202 0.185 106.02 116.87 111.45 7.67 
2-3 0.236 0.294 0.257 137.35 172.29 154.82 24.71 5-4 0.305 0.337 0.3 178.92 198.19 188.55 13.63 4-5 0.361 0.433 0.389 212.65 256.02 234.34 30.67 5-6 0.419 0.478 0.441 247.59 283.13 265.36 25.13 6-7 0.5 0.481 0.483 296.39 284.94 290.66 8.09 7-8 0.519 0.496 0.500 307.83 293.98 300.90 9.80 8-9 0.478 0.5 0.481 283.13 296.39 289.76 9.37 
1
VO 0 0.509 0.473 0.483 301.81 280.12 290.96 15.33 
1 
Appendix 3.4 (Continued) 
CORE *613: 10/85 
DILUTION FACTOR; 10 >EPTH INTERVAL (cm) 0D640-* *7a> 3 N/l of Pore Water-­A 6 NET AYE A CD AYE ±STD 
0-1 0.219 0.237 0.220 127.11 137.95 132.53 7.67 
-
1 2 0.277 0.311 0.286 162.05 182.53 172.29 14.48 2-3 0.326 0.337 0.324 191.57 198.19 194.88 4.69 3-4 0.399 0.365 0.374 235.54 215.06 225.30 14.48 4-5 0.401 0.436 0.411 236.75 257.83 247.29 14.91 5-6 0.433 0.481 0.449 256.02 284.94 270.48 20.45 6-7 0.466 0.478 0.464 275.90 283.13 279.52 5.11 7-8 0.43 0.488 0.451 254.22 289.16 271.69 24.71 8-9 0.437 0.477 0.449 258.43 282.53 270.48 17.04 
9-10 0.44 0.493 0.459 260.24 292.17 276.20 22.58 
CORE *633: 10/85 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) 0D640-• -Mg-atm N/l of Pore Water-­A B NETAYE A B AYE ±STD 
0-1 0.713 0.661 0.679 424.70 393.37 409.04 22.15 
1 2 0.162 0.154 463.86 463.86 
2-3 0.102 0.094 283.13 283.13 
3-4 0.076 0.068 409.64 409.64 

4-5 
----— -­
--— -­
5-6 
6-7 7-8 8-9 0.488 0.522 0.49? 289.16 309.64 299.40 14.48 
9-10 0.579 0.525 0.544 343.98 311.45 327.71 23.00 
3.4
Appendix (Continued) 
CORE *603: 12/4/85 
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  -0D640-•  -ug-atm N/l of Pore Water-­ 
A  6 NET AYE A B  AYE  ±STD  

0-1 0.068 0.074 0.065 37.35 38.55 37.95 0.85 
-
1 2 0.077 0.105 0.083 42.77 57.23 50.00 10.22 2-3 0.143 0.158 0.143 82.53 89.16 85.84 4.69 3-4 0.198 0.229 0.206 115.66 131.93 123.80 11.50 4-5 0.291 0.261 0.268 171.69 151.20 161.45 14.48 5-6 0.363 0.267 0.307 215.06 154.82 184.94 42.60 6-7 0.393 0.326 0.352 233.13 190.36 211.75 30.24 7-8 0.445 0.337 0.383 264.46 196.99 230.72 47.71 8-9 0.524 0.348 0.428 312.05 203.61 257.63 76.67 
9-10 0.5 0.356 0.420 297.59 208.43 253.01 63.04 
CORE *85: 
12/4/85 
DILUTION FACT0R:_ 10_ 
DEPTH INTERVAL (cm) 0D640-• jjuj-atm N/l ofPore Water-­A B NET AVE A B AYE ±STD 
0-t 0.208 0.124 0.156 119.28 68.67 93.98 35.78 
-
1 2 0.136 0.158 0.137 75.90 89.16 82.53 9.37 
2-3 0.123 0.129 0.116 68.07 71.69 69.88 2.56 
3-4 0.107 0.151 0.119 58.43 84.94 71.69 18.74 4-5 0.101 0.167 0.124 54.82 94.58 74.70 28.11 5-6 0.1 0.17 0.125 54.22 96.39 75.30 29.82 6-7 0.118 0.22 0.159 65.06 126.51 95.78 43.45 
7-8 0.112 0.236 0.164 61.45 136.14 98.80 52.82 8-9 0.117 0.294 0.196 64.46 171.08 117.77 75.40 
1 
i
cr> o 0.129 0.32 0.215 71.69 186.75 129.22 81.36 
3.4
Appendix (Continued) 
CORE *65: 12/4/85 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) 00640--ug-atm N/l ofPore Water-­A B NET AYE A 8 AYE ±STD 
0-1 0.093 0.154 0.116 50.00 89.16 69.58 27.69 
-
1 2 0.078 0.084 0.073 40.96 46.99 43.98 4.26 2-3 0.093 0.108 0.093 50.00 61.45 55.72 8.09 3-4 0.068 0.068 0.060 34.94 37.35 36.14 1.70 4-5 0.073 0.057 0.057 37.95 30.72 34.34 5.11 5-6 0.083 0.069 0.068 43.98 37.95 40.96 4.26 6-7 0.085 0.066 0.068 45.18 36.14 40.66 6.39 7-8 0.091 0.064 0.070 48.80 34.94 41.87 9.80 8-9 0.095 0.068 0.074 51.20 37.35 44.28 9.80 
9-10 0.093 0.08 0.079 50.00 44.58 47.29 3.83 
CORE *623: 12/4/85 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) 0D640---Mg-atmN/lofPoreWater-­A B NET AVE A 8 AYE ±STD 
0-1 0.149 0.09 0.115 86.75 50.60 68.6? 25.56 
-
1 2 0.132 0.114 0.118 76.51 65.06 70.78 8.09 .2-3 0.166 0.182 0.169 96.99 106.02 101.51 6.39 3-4 0.224 0.226 0.220 131.93 132.53 132.23 0.45 4-5 0.334 0.258 0.291 198.19 151.81 175.00 32.60 5-6 0.24 0.291 0.261 141.57 171.69 156.63 21.30 6-7 0.285 0.277 0.276 168.67 163.25 165.96 3.83 7-8 0.29 0.306 0.293 171.69 180.72 176.20 6.39 8-9 0.336 0.334 0.330 199.40 197.59 198.49 1.28 
1 
i
a* o 0.332 0.355 0.339 196.99 210.24 203.61 9.37 
1 
Appendix 3.4 (Continued) CORE *45: 12/4/85 

DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  --0D640-•  -ug-atm N/l ofPore Water-­ 
A  B  NET AYE  A  B  AYE  ±STD  
0-1  0.076  0.127  0.092  39.76  70.48  55.12  21.72  
1 -2  0.134  0.093  0.104  74.70  83.35  79.02  6.12  
2-3  0.042  0.187  0.105  96.39  106.63  101.51  7.24  
3-4  0.168  0.256  0.202  95.18  148.19  121.69  37.49  
4-5  0.185  0.26  0.213  105.42  150.60  128.01  31.95  
5-6  0.208  0.233  0.211  119.28  134.34  126.81  10.65  
6-7  0.152  0.215  0.174  85.54  123.49  104.52  26.84  
7-8  0.153  0.203  0.168  86.14  116.27  101.20  21.30  
8-9  0.128  0.168  0.138  71.08  95.18  83.13  17.04  
9-10  0.132  0.156  0.134  73.49  87.95  80.72  10.22  

Appendix 3.4 (Continued) 
CORE *613: 12/4/85 
DILUTIONFACTOR: 10 >EPTH INTERVAL (cm) -00640--ug-atm N/l of Pore Water-­A B NET AYE A 6 AYE ±STD 
0-1 0.093 0.085 0.081 50.00 45.18 47.59 3.41 
-
1 2 0.122 0.115 0.111 67.47 63.25 65.36 2.98 2-3 0.127 0.143 0.127 70.48 80.12 75.30 6.82 3-4 0.083 0.186 0.127 43.98 106.02 75.00 43.87 
4-5 0.213 0.219 0.208 122.29 125.90 124.10 2.56 5-6 0.273 0.263 0.260 158.43 152.41 155.42 4.26 6-7 0.297 0.305 0.293 172.89 177.71 175.30 3.41 7-8 0.318 0.317 0.310 185.54 184.94 185.24 0.43 
8-9 0.341 0.358 0.342 199.40 209.64 204.52 7.24 9-10 0.35 0.372 0.353 204.82 218.07 211.45 9.37 
CORE *633: 12/4/85 
DILUTION FACTOR: 10 
)EPTH INTERVAL (cm) 00640-• -Mg-atmN/lofPoreWater-­A B NET AYE A B AYE ±STD 
0-1 0.164 0.207 0.180 95.18 121.08 108.13 18.32 
1 2 0.263 0.257 154.82 2-3 0.36 0.354 213.25 3-4 0.09 0.061 0.070 126.51 33.13 79.82 66.03 4-5 0.071 0.065 39.16 
5-6 
6-7 

7-8 0.481 0.586 0.528 286.14 87.35 140.57 8-9 0.382 0.592 0.481 226.51 88.25 157.38 97.76 9-10 
3.4
Appendix (Continued) Appendix 3.4 (Continued) 
CORE *603; 2/5/86  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
(cm)  0D640-­ —  —-ug-atm N/l of Pore Water—  
A  B  NET AYE  A  B  AYE  ±STD  
0-1  0.097  0.095  0.088  53.61  52.41  53.01  0.85  
1 -2  0.091  0.131  0.103  50.00  74.10  62.05  17.04  
2-5  0.136  0.188  0.154  77.11  108.43  92.77  22.15  
3-4  0.202  0.271  0.229  116.87  158.43  137.65  29.39  
4-5  0.311  0.334  0.315  182.53  196.39  189.46  9.80  
5-6  0.337  0.408  0.365  198.19  240.96  219.58  30.24  
6-7  0.404  0.43  0.409  238.55  254.22  246.39  11.08  
7-8  0.404  0.501  0.445  238.55  296.99  267.77  41.32  
8-9  0.455  0.489  0.464  269.28  289.76  279.52  14.48  
9-1 0  0.464  0.484  0.466  274.70  286.75  280.72  8.52  
CORE *85^2/5/86  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  0D640-• —  —-jig-atm N/l ofPore Water-­ 
A  B  NET AVE  A  B  AYE  ±STD  
0-1  0.221  0.141  0.173  128.31  80.12  104.22  34.08  
1 -2  0.373  0.221  0.289  219.88  128.31  174.10  64.75  
2-3  0.632  0.356  0.486  375.90  209.64  292.77  117.57  
3-4  0.793  0.532  0.655  472.89  315.66  394.28  111.18  
4-5  1.138  0.775  0.949  680.72  462.05  571.39  154.63  
5-6  1.414  0.921  1.160  846.99  550.00  698.49  210.00  
6-7  1.398  0.996  1.189  837.35  595.18  716.27  171.24  
7-8  1.552  1.224  1.380  930.12  732.53  831.33  139.72  
8-9  1.594  1.191  1.385  955.42  712.65  834.04  171.6?  
9-10  1.724  1.295  1.502  1033.73  775.30  904.52  182.74  

CORE *65: 2/5/86 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) -00640--ug-atm N/l of Pore Water-­A B NET AYE A B AYE ±STD 
0-1  0.135  0.08  0.100  76.51  72.30  74.40  2.97  
1  -2  0.08  0.178  0.121  43.37  102.41  72.89  41.74  
2-3  0.126  0.157  0.134  71.08  89.76  80.42  13.21  
3-4  0.159  0.245  0.194  90.96  142.77  116.87  36.63  
4-5  0.139  0.241  0.182  78.92  140.36  109.64  43.45  
5-6  0.123  0.265  0.186  69.28  154.82  112.05  60.49  
6-7  0.126  0.2  0.155  71.08  115.66  93.37  31.52  
7-8  0.131  0.171  0.143  74.10  98.19  86.14  17.04  
8-9  0.163  0.144  0.146  93.37  81.93  87.65  8.09  
9-10  0.176  0.148  0.154  101.20  84.34  92.77  11.93  

CORE *623:2/5/86 
DILUTION FACTOR: 10 
)£PTH INTERVAL (cm) 0D640-• -Mg-atm N/l of Pore Water-­A 6 NET AYE A B AYE ±STD 
0-1 0.103 0.098 0.093 57.23 54.22 55.72 2.13 
-
1 2 0.088 0.137 0.105 48.19 77.71 62.95 20.87 2-3 0.112 0.149 0.123 62.65 84.94 73.80 15.76 3-4 0.126 0.187 0.149 71.08 107.83 89.46 25.98 4-5 0.147 0.176 0.154 83.73 101.20 92.47 12.35 5-6 0.162 0.189 0.168 92.77 109.04 100.90 11.50 6-7 0.178 0.178 0.170 102.41 102.41 102.41 0.00 7-8 0.175 0.196 0.178 100.60 113.25 106.93 8.95 8-9 0.184 0.206 0.187 106.02 119.28 112.65 9.37 9-10 0.178 0.212 0.187 102.41 122.89 112.65 14.48 
Appendix 3.4 (Continued) 

CORE *45^2/5/86  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
(cm)  -0D640-•  -Mg-atm N/1 ofPore Water-­ 
A  B  NET AYE  A  B  AYE  ±STD  
0-1  0.163  0.116  0.132  93.37  65.06  79.22  20.02  
1 -2  0.134  0.053  0.086  75.90  27.11  51.51  34.50  
2-3  0.079  0.069  0.066  42.77  36.75  39.76  4.26  
3-4  0.09  0.095  0.085  49.40  52.41  50.90  2.13  
4-5  0.103  0.127  0.107  57.23  71.69  64.46  10.22  
5-6  0.142  0.174  0.150  80.72  100.00  90.36  13.63  
6-7  0.036  0.06  0.040  168.67  104.41  136.54  45.44  
7-8  0.042  -­ 0.034  204.82  -­ 204.82  -­ 
8-9  -­ -­ -­ -­ -­ -­ -­ 
9-10  -­ -­ -­ -­ -­ -­ -­ 

Appendix 3.4 (Continued) 
CORE *613; 2/5/86 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) -00640-• -ug-atm N/1 of Pore Water-­A B NET AYE A B AYE ±STD 
0-1 0.062 0.057 0.052 32.53 29.52 31.02 2.13 
-
t 2 0.056 0.081 0.061 28.92 43.98 36.45 10.65 2-3 0.082 0.113 0.090 44.58 63.25 53.92 
13.21 
3-4 0.11 0.15 0.122 61.45 85.54 73.49 17.04 
4-5 0.153 0.183 0.160 87.35 105.42 96.39 12.78 
5-6 0.186 0.227 0.199 107.23 131.93 119.58 17.46 
6-7 0.224 0.281 0.245 130.12 164.46 147.29 24.28 7-8 0.238 0.321 0.272 138.55 188.55 163.55 35.36 8-9 0.28 0.354 0.309 163.86 208.43 186.14 31.52 
9-10 0.274 0.387 0.323 160.24 228.31 194.28 48.13 
_ 
CORE *633: 2/5/86 
DILUTION FACTOR; 
1£ 
JEPTH INTERVAL (cm) 0D640--jjuj-atm N/1 of Pore Water-­
• 
A B NET AYE A B AYE ±STD 
0-1 0.26 0.172 0.208 151.81 98.80 125.30 37.49 
-
1 2 0.285 0.251 0.260 166.87 146.39 156.63 14.48 
2-3 0.351 0.292 0.314 206.63 171.08 188.86 25.13 3-4 0.539 0.367 0.445 319.88 216.27 268.07 73.27 4-5 0.623 0.471 0.539 370.48 278.92 324.70 64.75 5-6 0.753 0.574 0.656 448.80 340.96 394.88 76.25 
6-7 0.848 0.708 0.770 506.02 421.69 463.86 59.64 7-8 0.854 0.832 0.835 509.64 496.39 503.01 9.37 8-9 0.854 0.818 0.828 509.64 487.95 498.80 15.33 
9-10 0.885 1.097 0.983 528.31 656.02 592.17 90.31 
Appendix 3.4 (Continued) 

CORE *603: 4/9/86  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  --0D640-*  -ug-atm N/l of Pore Water-­ 
A  B  NET AYE  A  B  AYE  ±STD  
0-1  0.114  0.347  0.226  65.66  205.42  135.54  98.82  
1 -2  0.123  0.326  0.220  71.08  192.77  131.93  86.05  
2-3  0.186  0.389  0.283  109.04  230.72  169.88  86.05  
3-4  0.232  0.408  0.315  136.75  242.17  189.46  74.54  
4-5  0.262  0.423  0.338  154.82  251.20  203.01  68.15  
5-6  0.324  0.448  0.381  192.17  266.27  229.22  52.39  
6-7  0.388  0.507  0.443  230.72  301.81  266.27  50.26  
7-8  0.435  0.552  0.489  259.04  328.92  293.98  49.41  
8-9  0.495  0.598  0.542  295.18  356.63  325.90  43.45  
9-10  0.541  0.646  0.589  322.89  385.54  354.22  44.30  
CORE  
DILUTION FACT0R:_  10  
DEPTH INTERVAL  
(cm)  0D640-•  -jig-etm N/l ofPore Water-­ 
A  B  NET AVE  A  B  AYE  ±STD  
0-1  0.204  0.12  0.156  118.07  68.67  93.37  34.93  
1 -2  0.156  0.099  0.122  89.16  56.02  72.59  23.43  
2-3  0.072  0.078  0.069  38.55  43.37  40.96  3.41  
3-4  0.087  0.082  0.079  47.59  45.78  46.69  1.28  
4-5  0.093  0.095  0.088  51.20  55.61  52.41  1.70  
5-6  0.102  0.109  0.100  56.63  62.05  59.34  3.83  
6-7  0.113  0.12  0.111  63.25  68.67  65.96  3.83  
7-8  0.13  0.139  0.129  73.49  80.12  76.81  4.69  
8-9  0.149  0.148  0.143  84.94  85.54  85.24  0.43  
9-10  0.133  0.172  0.147  75.30  100.00  87.65  17.46  

Appendix 3.4 (Continued) 
CORE *65: 4/9/86 
, 
DILUTION FACTOR; 10 )EPTH INTERVAL (cm) -0D640--Mg-atmN/lofPoreWater-­
—
A B NET AYE A 8 AYE ±STD 
0-1 0.117 0.292 0.199 66.87 287.21 177.04 155.80 
-
1 2 0.13 0.251 0.185 74.70 246.03 160.37 121.15 
2-3 0.159 0.201 0.174 92.17 195.82 144.00 73.29 3-4 0.142 0.142 0.136 81.93 136.57 109.25 38.64 4-5 0.125 0.17 0.142 71.69 164.69 118.19 65.76 5-6 0.121 0.165 0.137 69.28 159.67 114.47 63.92 6-7 0.141 0.191 0.160 81.33 185.78 133.55 73.86 7-8 0.143 0.306 0.219 82.53 301.27 191.90 154.67 
8-9 0.149 0.197 0.167 86.14 191.81 138.98 74.71 9-10 0.146 0.248 0.191 84.34 243.02 163.68 112.21 
CORE *623; 4/9/86 
DILUTION FACTOR; 10 
)EPTH INTERVAL (cm) -0D640-• -Mg-atmN/1ofPoreWater-­
——
A B NET AYE A B AYE ±STD 
0-1 0.113 0.15? 0.130 64.46 91.57 78.01 19.1? 
-
1 2 0.149 0.188 0.164 86.14 110.24 98.19 17.04 2-3 0.142 0.214 0.173 81.93 125.90 103.92 31.10 3-4 0.139 0.209 0.169 80.12 12Z.89 101.51 30.24 4-5 0.156 0.189 0.168 90.36 110.84 100.60 14.48 
5-6 0.203 0.166 0.190 118.67 109.04 113.86 6.82 
6-7 0.21 0.185 0.193 122.89 108.43 115.66 10.22 7-8 0.22 0.181 0.196 128.92 106.02 117.47 16.19 8-9 0.198 0.194 0.191 115.66 113.86 114.76 1.28 
9-10 0.221 0.221 0.216 129.52 130.12 129.82 0.43 
Appendix 3.4 (Continued) 

CORE *45i4/9/86  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  0D640-•  -Mg-atm N/l ofPore Water-­ 
A  B  NET AYE  A  B  AYE  ±STO  
0-1  0.064  0.238  0.146  35.54  138.55  87.05  72.84  
1 -2  0.058  0.141  0.095  31.93  200.30  116.11  119.06  
2-3  0.092  0.305  0.194  52.41  223.64  138.03  121.08  
3-4  -­ -­ -­ -­ -­ -­ -­ 
4-5  -­ -­ -­ -­ -­ -­ -­ 
5-6  -­ -­ -­ -­ -­ -­ -­ 
6-7  -­ -­ -­ -­ -­ -­ -­ 
7-8  -­ -­ -­ -­ -­ -­ -­ 
8-9  -­ -­ -­ -­ -­ -­ -­ 
9-10  -­ -­ -­ -­ -­ -­ -­ 

3.4
Appendix (Continued) 
CORE *613: 4/9/86
-
DILUTION FACTOR: 10 )EPTHINTERVAL (cm) -ug-atm N/l of Pore Water—
-0D640-• A 0 NET AYE A B AYE ±STD 
0-1 0.096 0.126 0.106 54.82 72.89 63.86 12.78 
-
1 2 0.074 0.098 0.081 41.57 56.02 48.80 10.22 2-3 0.056 0.083 0.065 30.72 46.99 38.86 11.50 3-4 0.054 0.078 0.061 29.52 43.98 36.75 10.22 4-5 0.078 0.089 0.079 43.98 50.60 47.29 4.69 5-6 0.103 0.107 0.100 59.04 61.45 60.24 1.70 6-7 0.136 0.135 0.131 78.92 78.31 78.61 0.43 7-8 0.174 0.185 0.175 101.81 108.43 105.12 4.69 8-9 0.247 0.24 0.239 145.78 141.57 143.67 2.98 
9-10 0.306 0.278 0.287 181.33 164.46 172.89 11.93 
CORE *633; 4/9/86 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) 0D64O--Mg-atmN/lofPoreWater-­
• 
A B NET AYE A B AYE ±STD 
0-1 0.243 0.27 0.250 143.07 159.04 151.05 11.29 
-
1 2 0.294 0.358 0.319 173.80 212.05 192.92 27.05 
2-3 0.346 0.391 0.362 205.12 231.93 218.52 18.96 
.3-4 0.192 0.376 0.277 280.87 222.89 251.88 41.00 4-5 0.258 0.408 0.326 380.27 242.17 311.22 97.65 5-6 0.738 0.439 0.582 441.27 260.84 351.05 127.58 6-7 0.767 0.512 0.633 458.73 304.82 381.78 108.83 7-8 0.869 0.541 0.698 520.18 322.29 421.23 139.93 8-9 0.916 0.587 0.745 548.49 350.00 449.25 140.36 
9-10 0.982 0.643 0.806 588.25 383.73 485.99 144.62 
Appendix  3.4 (Continued)  
CORE *603: 6/4/86  
DILUTION FACTOR:  to  
DEPTH INTERVAL  
(cm)  0D640-•  -jig-atm N/l of Pore Water  
A  B  NET AYE  A  B  AYE  ±STD  
0-1  65.06  70.48  67.77  3.83  
1  -2  90.96  77.71  84.34  9.37  
2-3  89.16  78.92  84.04  7.24  
3-4  97.59  88.55  93.07  6.39  
4-5  110.84  102.41  106.63  5.96  
5-6  128.92  128.31  128.62  0.43  
6-7  139.16  143.37  141.27  2.98  
7-8  168.00  151.20  159.60  11.88  
8-9  180.72  175.30  178.01  3.83  
9-10  184.94  201.20  193.07  11.50  
CORE *85: 6/4/86  
DILUTION FACTOR;  10  
DEPTH INTERVAL  
(cm)  0D640-•  -jjuj-atm N/1 of Pore Water  
A  B  NET AVE  A  8  AVE  ±STO  
0-1  80.72  61.45  71.09  13.63  
1  -2  101.20  62.65  81.93  27.26  
2-3  83.13  57.23  70.18  18.31  
3-4  60.84  48.80  54.82  8.51  
4-5  62.65  50.00  56.33  8.94  
5-6  63.86  56.63  60.25  5.11  
6-7  71.08  61.45  66.27  6.81  
7-8  74.10  68.07  71.09  4.26  
8-9  72.89  75.90  74.40  2.13  
9-10  98.19  74.70  86.45  16.61  

Appendix 3.4 (Continued) 
CORE *65:6/4/86 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) -00640--ug-atm N/l of Pore Water
—
A B NET AYE A B AYE ±3TD 
0-I 58.43 48.80 53.62 6.81 1 2 89.76 72.29 81.03 12.35
-
2-3 85.54 85.54 3-4 152.41 152.41 4-5 125.90 55.42 90.66 49.84 5-6 96.38 30.72 63.55 46.43 6-7 62.65 69.28 65.97 4.69 7-8 45.18 42.77 43.98 1.70 8-9 92.17 46.38 69.28 32.38 
9-10 36.14 46.39 41.27 7.25 
CORE *623: 6/4/66 
DILUTION FACTOR: 10 )EPTH INTERVAL (cm) 0D640 -jig-atm N/l of Pore Water
—
A B NET AYE A B AYE ±STD 
0-1 59.04 27.11 43.08 22.58 1 2 134.34 76.51 105.43 40.89
-
2-3 162.05 110.84 136.45 36.21 3-4 190.96 105.42 148.19 60.49 4-5 198.80 95.78 147.29 72.85 5-6 207.83 90.36 149.10 83.06 6-7 235.54 80.72 158.13 109.47 7-8 252.41 77.71 165.06 123.53 8-9 263.25 81.93 172.59 128.21 
9-10 
288.55 89.76 189.16 140.57 
95  
Appendix 3.4 (Continued) Core #613­6/4/86 "  
Depth Interval (cm)  A  -atm N/l of Pore Water B AVE  +STD  
0  --1  65.66  65.66  65.66  0.00  
1  --2  84.34  66.87  75.61  12.35  
2  --3  82.53  62.65  72.59  14.06  
3  --4  69.88  60.84  65.36  6.39  
4  --5  63.86  56.02  59.94  5.54  
5 6  --6 --7  66.86 71.08  60.84 63.25  63.85 67.17  4.26 5.54  
7  --8  77.71  72.89  75.30  3.41  
8  --9  95.18  89.76  92.47  3.83  
9  --10  114.46  115.66  115.03  0.81  

3.4
Appendix (Continued) 
CORE *45: 6/4/86  
DILUTION FACTOR:  10  
DEPTH INTERVAL  
(cm)  -0D640  -Mg-atm N/l of Pore Water- 
A  B  NET AYE  A  B  AYE  ±STD  
0-1  107.23  —  107.23  —  
1  -2  153.01  -­ 153.01  -­ 
2-3  168.07  -­ 168.07  -­ 
3-4  194.58  -­ 194.58  -­ 
4-5  165.06  -­ 165.06  -­ 
5-6  193.37  -­ 193.37  -­ 
6-7  241.57  -­ 241.57  -­ 
7-8  248.80  -­ 248.80  -­ 
8-9  266.27  -­ 266.27  -­ 
9-10  __  286.14  -­ 286.14  -­ 

97  
Appendix  3.4 (Continued)  
Table  .  Core #633'-6/4/86  
Depth  Interval  U&i-atm N/l of Pore Water  
(cm)  A  B  AVE  +STD  
0  -1  124.70  118.07  121.39  4.69  
I  -2  283.13  422.29  352.71  98.40  
2  -3  265.06  521.69  393.38  181.46  
3  -4  168.67  428.31  298.49  183.59  
4  -5  291.16  554.22  422.69  186.01  
5  -6  - - - - 
.  6  -7  - - - - 
7  -8  - - - - 
8  -9  - - - - 
9  -10  221:91  227.91  _  

Appendix 3.4 (Continued) 
CORE *603:8/6/86 
D1UTI0NFACTOR; 10 
)EPTH INTERVAL  
ICCTU  nvxnVVv"fU  jAy  dunn/ 1 OT rOTc  IdW  
A  B  NET AVE  A  B  AVE  ±STD  

0-1 78.31 80.12 79.22 128 
1 -2 120.48 118.67 119.58 \28 2-3 136.14 171.08 153.61 24.71 3-4 146.39 196.38 171.39 35.35 4-5 169.28 213.86 191.57 31.52 5-6 177.71 210.84 194.28 23.43 6-7 18253 215.06 198.80 23.00 7-8 189.76 207.00 198.38 12.19 00 cr> 194.58 218.07 20633 16.61
i 
9-10 196.99 230.72 213.86 23.85 
CORE *85: 8/6/86 
DILUTION FACTOR: 10 )EPTH INTERVAL -0D640
kcnv hmvi rwr mo 
A B NET AVE A B AVE ±STD 
0-1 
40.36 74.10 57.23 23.86 
1 -2 119.28 155.42 137.35 25.55 2-3 165.06 200.60 182.83 25.13 3-4 189.76 267.47 228.62 54.95 4-5 189.16 268.07 228.62 55.80 
5-6 127.11 234.34 180.73 75.82 6-7 151.20 267.47 209.34 82.22 
7-8 131.32 219.88 175.60 62.62 
8-9 116.87 201.20 159.04 59.63 9-10 109.04 189.76 149.40 57.08 
Appendix 3.4 (Continued) 
CORE *65:8/6/86 
DtUTION FACTOR: 10 
DEPTH INTERVAL  
. \ Lciru  m\£.AriUUtmr  i vi rw r w  
A  B  NET AVE  A  B  AVE  ±STD  

0-1 220.48 134.94 177.71 60.49 
t -2 250.60 173.49 212.05 54.53 2-3 
262.65 196.39 229.52 46.85 
3-4 265.06 203.42 235.24 42.17 4-5 200.00 189.16 194.58 7.67 5-6 179.52 204.82 192.17 17.89 6-7 135,34 210.24 172.89 52.82 7-8 121.08 207.83 164.46 61.34 8-9 107.83 207.23 157.53 7029 9-10 83.73 187.35 135.54 7327 
CORE «623:8/6/86 
DILUTIONFACTOR: 10 DEPTH INTERVAL (cm) -0D640 Hg-atmN/lofPoreVater
— 
A B NET AVE A B AVE ±STD 
0-1 131.93 62.65 9729 48.99 
-2 197.59 121.69 159.64 53.67 2-3 229.52 188.55 209.04 28.97 3-4 218.67 210.84 214.76 5.54 4-5 187.95 224.10 206.03 25.56 
5-6 176.51 230.72 203.62 38.33 6-7 210.84 217.47 214.16 4.69 7-8 200.60 189.76 195.18 7.67 8-9 190.36 178.31 184.34 8.52 
9-10 162.65 172.89 167.77 724 
Appendix  3.A (Continued)  
Core #45  -8/6/86  - 
Depth Interval  -at N/l of Pore Water  
(cm)  A  B  Ave.  +STD  
0 -1  - 124.70  124.70  - 
1  -2  150.60  122.74  136.67  19.70  
2  -3  242.47  - 242.47  - 
3  -4  211.45  - 211.45  - 
4  -5  168.67  211.69  195.18  37.49  
5  -6  - 286.14  286.14  - 
6  -7  - - - - 
7  -8  - - - - 
8  -9  - -_  - - 
9  - 10  _  

Appendix 3.4 (Continued) 
CORE *613; 8/6/86 
DILUTION FACTOR: 10 DEPTH WTERVAL 
/\ 
-
icmj WOHU 1 OT rOTr Iflin 
A B NET AVE A B AVE ±STD 
0-1 91.57 90.36 90.97 0.86 1 -2 134.33 116.87 125.60 12.35 2-3 154.22 123.49 138.86 21.73 
134.34 21.30 4-5 163.25 124.70 143.98 2726 5-6 171.08 117.47 14428 37.91 6-7 157,23 120.48 138.86 25.99 7-8 158.30 134.94 146.62 16.52 8-9 143.37 121.08 13223 15.76 
9-10 139.16 121.69 130.43 12.35 
3-4 149.40 11928 
CORE *633:: 8/6/86 
DLUTION FACTOR: 10 DEPTH INTERVAL (cm) 00640 Hg-atm H/lofPore'Vatet A B NET AVE A B AVE iSTD 
0-1 139.76 126.51 133.14 9.37 1 -2 240.36 239.76 240.06 0.42 2-3 300.00 289.76 294.88 724 3-4 315.06 348.80 331.93 23.86 4-5 310.84 328.31 319.58 12.35 5-6 313.25 336.14 324.70 16.19 
6-7 305.42 354.82 330.12 34,93 7-8 315.06 355.42 33524 28.54 8-9 337.95 367.47 352.71 20.87 CTs 0 31626 368.67 342.47 37.06
1 
102 
0.64 1,45 0.64 0.57 1.21 0.50 0.78
Aug'86 
2.89 0,47 2.20 0.99 0.73 0,97 0.54
Jun'86 
0.04 0.08 0.08 0.14 0.31 0.14 1.26
Apr’86 
0.62 0.46 0.44 0.81 0.84 0.84 2.04
Feb'86 
Column 0.66 0.34 0.36 0.47 1.24 0.53 0.31
Dec‘85 
Water 0.08 0.27 0.01 0.01 0.50 0.18 0.13
Oct'85 
the 
0.16 0.14 0.16 0.29 0.85 0.21 0.36in Aug'85 
0.41 0.19 0.19 0.17 0.31 0.27 0.25
Jul'85
Concentration 
0.58 0.12 0.09 0.00 3.37 1.33 0.81
Jun'85
Ammonium 
0.28 0.17 0.16 0.03 0.83 0.17 0.6?
May‘85 
0.09 0.04 0.03 0.02 0.10 0.01 0.02
3.5. 
Apr‘65 
2.47 0.79 1.18 0.45 0.36 0.39 0.19 1.
Appendix Mar'85 
per Cullen
5.26 2.98 6.01 0.90 0.42 0.42 — N Jan'65 — 
J.
pg-atm 
from 
—
0.59 0.72 0.55 0.62 0.71 1.38Nov'84 » 
Units Data 
# 45 65 85
603 613 623 633 
Station 
Appendix 3.6. Measured Allllß6lllttlß fIOX Stitin *O5 Chamber Experiments 
Sample  NH4-FLUX*­ 
Date  
-­ -<Mg-«tm N per  1  per h)—  (Mg-atm N p er m2 per h)  
Ch*l  Ch*2  AYE  Ch*l  Ch*2  AYE  ±STD  

YEAR*1 11/28/84 0.24 2.04 1.14 65.1 545.0 305.1 359.3 1/23/85 0.59 -0.68 -0.05... 160.1 -181.7 -10.8 241.7 
3/6/85 8.28 9.54 8.91 2247.4 2548.5 2398.0 212.9 4/3/85 -0.34 -0.36 -0.35 -92.3 -96.2 -94.2 2.7 5/8/85 0.31 0.21 0.26 84.1 56.1 70.1 19.8 6/5/85 0.47 0.41 0.44 133.2 114.4 123.8 13.3 
7/17/85 0.00 -0.05 -0.03 0.0 -14.0 -7.0 9.9 8/14/85 
«« «« 	****a 
YEAR *2 10/23/85 2.14 2.70 2.42 606.5 753.7 680.1 104.0 
12/4/85 3.24 3.95 3.60 918.3 1102.6 1010.5 130.3 2/5/86 4.33 5.83 5.08 1227.2 1627.4 1427.3 283.0 4/9/86 1.56 1.56 442.1 442.1
—	— — 
6/4/86 0.59 4.29 2.44 167.2 1197.5 682.4 728.5 8/6/86 0.07 2.02 1.05 19.8 563.9 291.9 384.7 
* 	= net NH4flux INTO sediment from veter column; "+" * net flux OUT OF sediment into veter col umn. 
** 	Semples lost. 
Units:Ammoniumfluxescither 1)wg-atmNperliterofporeveterperhour 
or 
2) jig-atm N per m~2 of sediment per hour. 
104 
. 
1 
29.5 31.0 60.8
Aug‘86 1.2, 101.5 118.1 /75.5 
top 
in 
8.3 9.0 3.6 3.2
27.0 69.1
Jun‘66 	221.8 
concentration
5.8 7 4.7 
10.8

74.5 6/.9 58.5 	depth.
49
Apr'86 
7.6 5.0 3.6 
Feb'86 36.4 55.6 24.5 13.3 increasing depth. ammonium column. 
with 
in 
water
4.7 6.1 2.2 5.8 10.8 with
27.4 54.6
Dec‘85 
Flux 	62.6 concentration difference overlying
5.0 9.4
88.9 122.4 240.8 
concentration
Oct'65 
from 
n 
M 
—
Ammonium Aug'85 848.2 104.4 568/ 486.7 /058.4 gradient: ammonium resulting in 
ammonium concentration
in 
_ 
in
85.9
Jul’85 5/5.9 528.0 486.4 522.2 660.6 ammonium gradient
Theoretical 	increase
increase ammonium
40.3 95.4 water 
7. 	J57.0 298.8 456.8 /29.6 
and 
3. Jun'85 	pore linear nonlinear theoretical 
—— 
Appendix 	“85 5 502.6 540.9 /88.6 328.3 — from from from fromMay 45/, segment 
110.5 95.4 
h.
Apr‘85 455.4 488.5 458.6 626.4 calculated Calculated Calculated Calculated sediment 
per 5 7 flux 
Mar'85 519.8 75/. /85.0 496./ 724.0 48/. 825.5 nT2 
per 2 
5 
1
ammonium 
Jan'85 462.2 464.2 285.8 559.8 4/0.0 — — N Method flatbed
pg-atm Method 
-rn-r a 	* 
Nov‘84 770. 75.2 897.5 559.6 947.5 Units Theoretical
.
# 45 65 85
603 613 623 633 
Station 
•' CHAPTER 4 
ZOOPLANKTON 
INTRODUCTION 
Zooplankton sampling was conducted to monitor the effects of freshwater 
inflow on the spatial and temporal distribution of zooplankton at seven 
stations in upper Lavaca Bay from November 1984 through August 1985 (Year 
1) and October 1985 through August 1986 (Year 2). In Year 2, sampling effort 
was increased to cover marine input from the lower bay by adding six stations 
along a transect from state highway 35 causeway south along the Matagorda 
Ship Channel to markers 35 and 36. Historical and concurrent stream flow 
data indicate that Year 1 was a wet year and Year 2 was a drier year. 
Zooplankton data reflect these differences. 
METHODS 
Zooplankton surface samples were collected in duplicate at each station 
with the exception of the river stations 45 and 65 where a third oblique tow 
from the bottom to the surface was taken during Year 2. Tows were not 
replicated at stations 1,2, 3, 1505, 1905, and 35-36 during Year 2. A 0.5 m 
diameter #lO mesh (153 #m) plankton net equipped with a General Oceanics 
2030 R flowmeter was used for sampling. Tows were of one minute duration. 
Ctenophores collected were volumetrically measured then dissolved in a weak 
solution of chlorox and washed through the plankton net to retain any other 
zooplankton which may have adhered to the jelly. Plankton samples were then 
washed into a 1 liter jar and preserved with 5% buffered formalin. 
Zooplankton were determined from species counts of aliquots 
taken with a Hensen-Stemple pipette. Each sample was diluted to a measured 
The to
volume (200 to 500 ml) and subsampled twice. first sample (1 10 ml) 
was used to determine the most abundant organisms, and the second (10-20 ml) 
was used to estimate organisms not represented in the first subsample. The 
remainder of the sample was then scanned at 12X for the larger, usually less 
abundant zooplankton. Aliquots were placed in a Ward zooplankton counting 
wheel and examined with a dissecting microscope at 25X. Triplicate 10 ml 
subsamples were taken from replicate A for dry weight. These samples were 
filtered onto a pre-weighed glass fiber filter, dried at 60°C for 24 hours, and 
weighed using an analytical balance. 
Statistical analyses included linear regressions and Spearman correlations 
to test for the significance of freshwater inflow and salinity at stations 45, 65 
and 85 and for Acartia tonsa length versus salinity correlations. 
Organisms were identified to species where possible. Counts and biomass 
measurements are reported in numbers per cubic meter of water sampled. A 
zooplankton species list is given in Table 4.1. 
RESULTS 
Community Description 
Zooplankton total abundance for Year 1 and Year 2 is presented in Table 
4.2. Although there was a major difference in inflow into upper Lavaca Bay 
for the two sampling periods, there was basically no difference in the overall 
zooplankton average standing crop for stations 45 through 633. On the basis 
of these data the upper bay stations are characterized throughout most of the 
as having low densities. During this study, highest densities in the upper
year 
in These
bay occurred the summer months of June 1985 and August 1986. 
density peaks occurred at stations 623 and 633. Additional data from stations 
established in Year 2 depict a zone of higher zooplankton abundance associated 
with a salinity gradient from the upper to lower bay. These data will be 
presented in detail under another topic. 
Zooplankton dry weights by stations are listed in Table 4.3. 
Since formalin preservation results in a significant loss of dry weight, the 
weights for zooplankton were adjusted by adding a 29.5% correction factor to 
the original dry weights (Durbin and Durbin, 1978). Stations 45, 65, and 603 
in close proximity to the major of freshwater were
source inflow, consistently 
lower than other sites. Biomass weights overall for the upper bay were higher 
in Year 1 than Year 2. During Year 1 environmental factors, i.e. high wind 
and freshwater inflows, increased the detritus and sediment load in the water 
column which resulted in artificially higher biomass weights at certain stations 
(Table 4.3). Secchi disc measurements (Fig. 1.5) are also indicative of higher 
sediment and detritus loads in the water column in Year 1. Attempts were 
made to develop a correction factor for stations with detritus but apparent 
variation in weight of different species of zooplankton made it unfeasable. In 
Narragansett Bay, Rhode Island zooplankton collected on the same day from 
different stations sometimes showed significant differences in weight for a 
given length (Durbin and Durbin, 1978). The differences in the condition 
factor appeared to be related to food availability. 
The average weight per individual zooplankter in Lavaca Bay was 0.017 
mg. When this value was used as a correction factor the biomass at some of 
the stations with large amounts of detritus decreased while others increased. 
The weight of 0.017 was comparable to adult weights for Acartia tonsa
mg 
which from approximately 0.01 for adults to 0.005 mg for first stage
range mg 
copepodites (Miller et al., 1977). A correction factor which may be adequate 
for one species, i.e. A. tonsa is not adequate when other species with 
, 
different weights are represented in a sample. 
During Year 2 sediment loading was not a problem and biomass 
measurements were usually indicative of zooplankton standing crops. With few 
exceptions the upper bay biomass was always lower than the stations south of 
the state highway 35 causeway. 
Inflow Effects 
The presence of freshwater zooplankton is indicative of freshwater inflow 
into the study area prior to or during a sampling trip and the extent of spatial 
distribution of freshwater species throughout the study area relates to the 
the From March
magnitude of event. 1985 through May 1985, persistent low 
salinities allowed the dispersal of a freshwater zooplankton community 
throughout the bay (Table 4.4). A decline in numbers of freshwater
upper 
species was evident from June 1985 through August 1986 with the exception of 
minor influxes of freshwater species in December 1985 and June 1986. Inflow 
events in December 1985 and June 1986 were small compared to flood events 
from March and May 1985 and were restricted principally to river stations 45 
and 65 and lake stations 603 and 613. 
Due to the shallow depth of most stations, only surface plankton tows 
were made with the exception of stations 45 and 65 in the river where depths 
of 4.5 and 4.9 m were measured. On occasion, stratification was noted at 
these stations, so in Year 2 an additional oblique tow was added to check for 
zooplankton stratification (Table 4.5). These data present surface standing 
crop abundance versus abundance for oblique tows and their relation to salinity 
1985
and oxygen, which can be used to verify stratification. In October 
(stations 45 and 65), December 1985 (station 65) and in June 1986 (station 65), 
stratification was evident from salinity measurements and was also apparent 
from the surface and oblique tow standing crop values. Lower standing crops 
were generality associated with lower salinity surface waters while higher 
counts of estuarine species were found in bottom water. In June 1986, 
stratification resulted in low dissolved below 1.0 m at stations 45 and
oxygen 
65. Standing crops were low in the surface and subsurface waters at station 
45 while higher standing crops were found subsurface at station 65. These 
data support the stratification conditions at the deeper river sites as noted in 
the hydrographic sections of Chapter 2. 
The incremental increase of estuarine and the decrease of freshwater 
zooplankton with distance, starting from the source of freshwater (station 45) 
and going downriver (station 65) to the open bay (station 85), is shown in 
Figure 4.1. Obvious trends are for estuarine zooplankton to decline, especially 
upriver during periods of peak inflow. Freshwater species increase during the 
inflow events and decrease in density as they move downstream. The results 
of linear regressions with estuarine and freshwater zooplankton, versus salinity 
and inflow, and inflow versus salinity using Spearman Correlations are as 
follows: 
Spearman Correlation 
Variables Stations: 45 65 85 
Streamflow vs. -0.7 -0.91 -0.68 Salinity <0.005 <O.OOOl <O.OOB 
Salinity vs. 0.42 0.77 -0.15 Estuarine species <0.002 
-
Salinity vs. -0.76 -0.92 -0.74 
Freshwater species <0.002 <O.OOOl <0.0003 
Streamflow vs. -0.67 -0.71 -0.26 Estuarine species 0.009 <0.005 
Streamflow vs. 0.93 0.94 0.7 Freshwater species <O.OOOl <O.OOl <0.005 
inflow and
These tests indicate that changes in response to salinity on 
standing crop values of estuarine and freshwater zooplankton are significant in 
most cases at the river stations 45 and 65 and at station 85 which is ,the 
nearest open bay station to the river mouth. 
Species Accounts 
Acartia tonsa was the most abundant copepod collected during this study 
and in most other estuarine zooplankton studies. Abundance, spatial and 
temporal distributions for A. tonsa are shown in Table 4.6. A. tonsa was 
found throughout the study at all stations with the exception of surface tows 
at station 45 in March and May 1985 when the streamflow was highest, 926 
c.f.s. and 1913 c.f.s. and the salinity was low, 0.8 and 0.2 %o respectively. The 
lowest densities were associated with the lower salinity stations 45, 65 and 
603. Highest seasonal densities in the upper bay occurred in the summer 
months of June 1985 and August 1986 at stations 623 and 633. These peaks 
correspond to the peak densities for the total zooplankton standing crop. 
Apparent seasonal lows were in the winter or early spring months of March 
1986 and February 1986 in the upper and lower bay. It is difficult to 
distinguish between salinity related lows and normal seasonal lows in the upper 
bay since this area is subject periodic freshwater flushing. The upper bay
to 
lows for A. tonsa were associated with salinities from 0.5 to 6.4% in March 
1985 and from 5.3 to 13.6%0 in February 1986. 
bloom of A tonsa occurred at the lower bay stations in April 1986 but
A 
, 
was not evident in the upper bay. 
In Year 2 A. tonsa was always more abundant in the lower than the 
with the exception of August 1986 where a bloom of A. tonsa was
upper bay, 
found at stations 633 and 623. Note that the upper bay was recovering from a 
freshwater inflow event in June 1986 and the salinity at stations 623 and 633 
was 9.8 and 8.9 respectively. These salinities were at the low end of the 
salinity range for the ctenophore, Mnenopsis mccradyiia copepod predator;
, 
which was at peak abundance at station 85 and most of the lower bay. High 
densities of M. mccradyi in the lower bay may have been responsible for this 
A. tonsa density shift. 
The total length of approximately 20 adult A. tonsa males and 20 females 
with spermatophores attached were measured at each station from October 1985 
through August 1986 to test for a length relationship along a salinity gradient. 
Measurements were taken from the tip of the the end of the sth
prosome to 
thoracic segment at 50X using an ocular micrometer with a dissecting 
microscope. The salinity ranged from 0.1 to 35,2%0. Female lengths ranged 
from 0.56 to 1.0 mm with a mean of o.7mm and the male lengths ranged from 
0.48 to 0.88 mm with a mean of 0.62 mm. Linear regression of length versus 
salinity demonstrated a significant length increase with salinity increase (P < 
0.0005; Figs. 4.2-4.3). Three dimensional graphs (Figs. 4.4-4.5) indicate two 
peaks for males and females, one at low salinity of small individuals and one 
at higher salinity of larger individuals. 
The ctenophore, Mnemiopsis mccradyi, a zooplankton predator, was absent 
or in low numbers in the bay from November 1984 through June 1985
upper 
during persistent low salinities (Table 4.7). Highest density occurred in August 
to station 65 and
1985 and 1986. In August -'1985 it was found upriver 
throughout the rest of the bay while in August 1986 its distribution was
upper 
85.
from the lower bay up to station Although similar salinity was 
encountered in the upper bay during August 1985-1986 (Table 2.3), ctenophore 
in at time The
colonization was more wide spread 1985 the of sampling. 
presence or absence of ctenophores from an area may affect zooplankton 
in the
density as was hypothesized to explain the decreased A. tonsa densities 
lower bay in August 1986. 
From October 1985 through August 1986, a 24-mile-long transect was 
sampled from station 45 near the source of freshwater inflow along a gradient 
to markers 35 and 36 in the Matagorda Ship Channel which were usually 
influenced by marine input from Pass Cavallo and the Matagorda Ship Channel. 
When average zooplankton densities for Year 2 by station are plotted from 
station 45 to 35-36 along the salinity gradient, the trend is for zooplankton 
density to increase from upper bay to the lower bay (Fig. 4.6). Salinity, 
densities of freshwater zooplankton, and the most abundant estuarine and 
marine species are plotted in Tables 4.8-4.10. Freshwater species abundance 
increased in December 1985 and June 1986 stations 45 and 65 corresponding
at 
to surface salinities of 0.8 and 1.4, and 0.6 and 1.0 °/oo respectively. 
Throughout the year, typical estuarine species, i.e. barnacle nauplii, Acartia 
tonsa, Paracalanus crassirostris, Pseudodioptomus and Oithona
coronatus, 
colcarva reached abundance in a zone between the freshwater 
, peak mid-bay 
and marine input. Incursions of marine fauna are indicated by the densities of 
the marine species Sagitta sp., Oikopleura and Noctiluca scintillans. In 
, 
October 
1985, densities of the larvacean Oikopleura ranged from 0.1/nv3 at 
station 45 to at station 35-36. Noctiluca scintillans a neritic 
, 
dinoflagellate, was -collected only in February and April 1986 with densities 
ranging from 0.1 at station 3 to at station 35-36 in February 1986. 
CONCLUSIONS 
Zooplankton occurrence and abundance in upper and lower Lavaca Bay 
were effected by freshwater inflow events and seasonality. As reported in 
previous studies (Holland et al. 1975, Gilmore et al. 1976, Matthews 1980, Kalke 
1981) flood events in an estuarine system usually result in the physical 
displacement of estuarine zooplankton with a population of freshwater species. 
In most cases the event is short term and salinity increases allow displaced 
estuarine species, i.e. Acartia tonsa, to recolonize quickly. The occurrence and 
distribution of freshwater zooplankton in upper Lavaca Bay from March 
through May 1985 reflect the influence of persistent low salinities during Year 
1 of this study. The two freshwater events associated with Year 2 that 
occurred in December 1985 and June 1986, mainly affected zooplankton 
populations at the river and lake stations. Although freshwater inflows were 
high in Year 1 compared to Year 2, there was no discernable difference in 
zooplankton numerical abundance between the two years. The seasonal highs 
for zooplankton abundance in the upper bay obviously occurred during the 
summer months of June 1985 in Year 1 and August 1986 in Year 2 as shown in 
Table 4.2. Seasonal cycles in the upper bay are sometimes difficult to 
ascertain because sporadic freshwater inflow events usually result in decreased 
zooplankton densities. 
Zooplankton dry weight biomass measurements in most cases were 
indicative of zooplankton abundance. During Year 1 there were problems with 
detritus and sediment in some samples due to heavy runoff and windy 
conditions. Biomass-results indicate that the river stations 45 and 65, and the 
upper lake station 603 are unstable in relation to zooplankton communities due 
to periodic flushing with freshwater. As the nutrients are transported to the 
and made under stable the
bay available more conditions, resulting higher 
zooplankton abundance increases biomass. According to biomass measurements 
in Year 2, the estuary is organized in zones grading from low salinity areas 
with low freshwater-estuarine zooplankton biomass, to a mid-bay zone with 
estuarine-zooplankton of high abundance and biomass, to a higher salinity zone 
of estuarine and neritic zooplankton which often has a biomass lower than the 
mid-zone of maximum production. 
The time of sampling in relation to the initiation and duration of a 
freshwater event is important. For example, if this study had begun in 
September 1984 the first trip would reflect conditions following a dry period; 
whereas, we first sampled in November 1984 following a peak freshwater event 
in October resulting in a freshwater signal. Freshwater zooplankton in an 
estuary can be used as tracers to follow incursions of freshwater inflow 
events. Estuarine and marine fauna can also be used to detect incursions of 
higher salinity waters into low salinity areas. 
A close relationship of zooplankton standing crop and Acartia tonsa 
density plots indicate the importance of A. tonsa as a dominant estuarine 
species. The lowest A. tonsa abundances were associated with the river 
stations 45 
and 65 and the upper lake station 603 which were most influenced 
by freshwater inflow. Relatively lower numbers of A. tonsa and other 
estuarine species in the upper bay during Year 1 indicated a need for expanded 
coverage to the lower bay to define the zone of maximum zooplankton density. 
Declines of A. tonsa densities in the bay in March 1985 and February
upper 
1986 were probably a seasonal' decline; however freshwater inflows in March 
1985 may have also caused low densities. While the seasonal highs for A.’ 
in 1985 and
tonsa in the upper bay occurred June August 1986, principally at 
stations 623 and 633 some distance from the mouth of the river, a comparable 
peak abundance in the lower bay area occurred in April 1986. These densites 
remained relatively high but declined through August 1986. In August 1986 a 
decline of A. tonsa occurred in the lower bay, where densities were normally 
higher than those in the upper bay. This decline may be related to the result 
of ctenophore predation by Mnemiopsis mccradyi, which were abundant in 
Matagorda Bay from station 1905 to station 85 in upper Lavaca Bay. 
The total length of adult A. tonsa males and females along a salinity 
gradient may provide data which can be linked with optimal growth conditions. 
Bagnall (1976) found A. tonsa males and females in the Gulf of Mexico to be 
larger than estuarine individuals from Christmas Bay near San Luis Pass, Texas. 
Males were reported as being smaller than females and the largest individuals 
occurred from February through May. Multiple regression of size on surface 
and
water temperature salinity did not explain a significant amount of 
variation in size observed in either males or females (Bagnall 1976). Similar 
results occurred in Lavaca Bay for male and female size differences, and a 
significant positive correlation of increased lengths with increased salinity was 
found. These data may be indicative of two different A. tonsa populations in 
the same or of size variations due to other environmental factors, i.e.
estuary 
a temperature/salinity effect. 
The greatest concentration of Mnemiopsis mccradyi in Lavaca Bay 
occurred during the summer months of August 1985 and 1986 which corresponds 
with large concentrations of copepods. The absence of Mnemiopsis from the upper bay during most of Year 1 indicates a low tolerance for low salinity 
conditions. Salinity increases during the August 1985 ctenophore bloom 
expanded the distribution of Mnemiopsis river to station 65, but during
up 
in in
their bloom August 1986, low salinity the upper bay above station 85 
restricted distribution to the middle bay stations. Concentration of Acartia 
result
tonsa during August 1986 apparently decreased as a of Mnemiopsis 
predation in the lower bay, while peak densities of Acartia tonsa were found 
in the upper bay in the absence of Mnemiopsis. Declines in zooplankton 
standing crop in Sandy Hook Bay, N.J. in July and August, 1969 were 
correlated with the presence of cnidarians and ctenophores (Sage and Herman, 
1972). 
Zooplankton data collected in Year 2 along a 24 mile transect from 
station 45 to markers 35-36 were useful for determining extent of freshwater 
inflow events and incursions of marine influence into the estuary. It also 
made it possible to determine areas of maximum zooplankton crop and
standing 
biomass. In Table 4.8 through 4.10, freshwater inflow events in December and 
June 1986 were minor and mainly influenced areas associated directly with the 
river, i.e. stations 45 and 65. Streamflow data shows that increased inflow the 
week after our June 1986 sampling trip was more extensive and most likely 
influenced areas beyond the river mouth. Periods of low river flow, i.e. 
October 1985, February and April 1986, result in higher salinities upriver and 
the encroachment of estuarine and marine species into the bay and river.
upper 
One example is the distribution of the marine species, Oikopleura sp. in 
October 1985, from a high of at station 35-36 to at station 45. 
As indicated by biomass during Year 2, distribution of freshwater, 
estuarine and marine zooplankton partitions the estuary into three zones. The 
upper zone near sources of freshwater inflow is subject to sporadic
-
environmental changes associated with salinity changes and the physical 
displacement of zooplankton communities by freshwater flood events. Estuarine 
species compete with fresh and brackish water species in this zone of low 
salinity tolerance. 
In a middle bay zone the salinities are normally more stable resulting in 
a buffer zone between the upper low salinity and lower high salinity marine 
environment. The area which represents this zone in Lavaca Bay is 
approximately between stations 85 and 1905. The most common zooplankton in 
this zone are considered estuarine species, i.e. barnacle nauplii, Acartia tonsa, 
Paracalanus crassiortus, Pseudodiaptomus , and Oithona colcarva. The
coronatus 
highest concentrations are normally found within this zone. 
The lower zone, of which station 35-36 seems to be on the inner edge of, 
is exposed to marine input from the Matagorda Ship Channel and Pass Cavallo. 
here
Although high densities of some estuarine species occur it also supports 
numbers of marine species associated with the neritic waters of the Gulf of 
Mexico. The extent to which marine species into the middle and
range upper 
bay is dependent on the salinity gradient established by freshwater inflow 
waters. 
REFERENCES 
Bagnall, R.A. 1976, Definition and persistence of an estuarine zooplankton 
assemblage. Houston: University of Houston, Texas, Dissertation, 139 p. 
Durbin, E.G. and A.G. Durbin, 1978. Length and weight releationships of 
Acartia clausi from Narragansett Bay, R.I. Limnol. Oceanogr. 23(5);958­
969. 
J. Means. 1976.
Gilmore, G.H., J. Dailey, M. Garcia, N. Hannebaum, A study of 
and nekton
the effects of fresh water on the plankton, benthos, 
of Tex. Pks. Wdlf.
assemblages the Lavaca Bay System, Texas. Dept., 
Coastal Fish., Div. Tech. Rep. to the Tex. Wat. Dev. Bd., 113 p. 
Holland, J.S, N.J. Maciolek, D. Kalke, H.L. Mullins, C.H. Oppenheimer. 1975. A 
benthos and plankton study of the Corpus Christi, Copano and Aransas 
Bay Systems 111. Report on data collected during the period July 1974 to 
May 1975 and summary of the three year project. Unpublished final 
report to the Texas Water Development Board. Port Aransas, TX: Univ, 
of Texas Mar, Sci. Inst. 1975; 174 p. 
Kalke, R.D. 1981. The effects of freshwater inflow on salinity and zooplankton 
populations at four stations in the Nueces-Corpus Christi and Copano­
-
Aransas Bay systems, Texas from October 1971 May 1975, pg. 454-471. 
In; R. Cross and D. Williams (eds.) Proc. Nat. Symp. Freshwater Flow to 
Estuaries, U.S. Fish and Wildlife Serv., Office Biological Serv., Publ. 
#FWSIOBS-81/04. 
Matthews, G.A. 1980. A study of the zooplankton assemblage of San Antonio 
Bay, Texas, and of the effects of river inflow on the composition and the 
persistence of this assemblage. College Station, Texas A&M University, 
Dissertation, 313 p. 
Miller, C.8., J.K. Johnson, and D.R. Heinle. 1977. Growth rules in the marine 
copepod genus Acartia. Limnol. Oceanogr. 22:326-335. 
Sage, L.E. and S.S.Herman. 1972. Zooplankton of the Sandy Hook Bay area, 
N.J. Ches. Sci. 13(l):29-39. 
Figure 4.1. Total abundance of estuarine and freshwater zooplankton 
species vs. the 14 day average streamflow for stations 
45, 65, and 85 from November 1984 through August 1986. 
of Acartia tonsa female total 
length vs. salinity for all stations from 
October 1985 through August 1986. 
Figure 4.2-. Linear regression 
4.3. 
-length 	vs. salinity for all stations from Ocober 1985 through August 1986. 
Figure Linear regression of Acartia tonsa male total 
18 
vs. 
data 
length female tonsa 
tia 
Acar 
of 
plot 
dimensional 

Three 
4.4. 
Figure 
1986 
August through 
1985 
October 

from 
stations 

all for 
salinity 

19 
vs. 
data 
length 
male tonsa 
Acartia 

of 
plot 
dimensional 

Three 
5. 
A. 
Figure 
1986 
August through 
1985 
October 

from 
stations 

all for 
salinity 

meter 
cubic 

per 
Count 

Zooplankton 

Average 

4.6. 
Figure 
986 
I 
Aug 
-
985 
1 
Oct 
-
Table 4.1. Lavaca Bay Zooplankton Species List, November 1984 Aug. 1986 
PHYLUM PROTOZOA¦ 
, 
Class Mastigophora Order Di noflagel1ata Noctiluca scintillans 
PHYLUM COELENTERATA 
Class Hydrozoa Solmaris sp. 
Class Scyphozoa 
Chrysaora quinquecirrha 
Stomolophus meleagris 
Medusae 
Class Anthozoa 
Anemone 

PHYLUM  CTENOPHORA  
Class  Tentaculata  
Mnemlopsis  mccradyi  
Class  Atentaculata  (Nuda)  
Beroe ovata  
PHYLUM  PLATYHELMINTHES  
Class  Turbellaria  
Order  Acoela  
FIatworm  
PHYLUM  NEMERTINEA  
Nemertean  
PHYLUM  ROTIFERA  
Keratella sp.  
Brachionus pii catills  
Platyias  quadricornis  
Platyias  patulus  
Rotifer  (unidentified)  
Rotifer  (colonial  form)  
Rotifer  (large,  soft body)  
PHYLUM  KINORYNCHA  
Ki norynch  
PHYLUM  NEMATODA  
Nematode  
PHYLUM  ANNELIDA  
Class  Polychaeta  
Polychaete  larvae  
Autolytus  prolifer  

Cl ass 01igochaeta 
01igochaetes 
C1 ass Hi rud inea 
Leech 
PHYLUM  MOLLUSCA  
Class  Gastropoda  Gastropod Pteropoda  larvae  

Cl ass Pelecypoda Pelecypod larvae 
Cl ass Cephalopoda Loligunculus brevis 
PHYLUM ARTHROPODA Class Arachnida Order Acarina Hydracarina (water mites) 
Cl ass Crustacea 
Order Di plostraca Penilia avirostris 
Sididae 
Oiaphanosoma sp. 
Daphnidae Ceriodaphnia sp. Daphnia sp. Moina 
sp. Moinodaphnia sp. 
Bosminidae Bosmina sp. 
Macrothricidae Ilyocryptus spinifer Macrothrix 
sp. 
Chidoridae Leydigea acanthoceroides 
Chydorus sp. 
Cladocera (unidentified) 

Order Myodocopi na Eusarsiella zostericola 
Order Podocopa Os traced (unidentified) 
Order Calanoida Calanoid (unidentified) Paracalanidae 
Paracalanus crassirostris 
Paracalanus 
sp. 
Centropagidae Centropages hamatus velificatus
Centropages 
Di aptomidae Diaptomus spp. Pseudodiaptomus 
coronatus 
Ca1anidae 
Eucalanus 

sp. 
Temoridae hirundoides
Eurytemora femora turbinata 
Pontel1idae 
Labidocera aestiva Labidocera scotti 
Pontella sp. 
Acarti idae 
Acartia tonsa 
Acartia tonsa copepodids Acartia tonsa adults 
Acartia liljeborgii 
Tortanidae Tortanus setacaudatus 
Order Harpacticoida Ameiridae Nitocra sp, Canue!1idae Scottolana canadensis 
Harpacticidae Harpacticus sp. Zausodes arenicolus 
Metidae 
Metis 

sp. 
Peltidi 	idae Alteutha depressa 
Tachiidae acutifrons
Euterpinna Microarthridion littorale 
Tegastidae 
Parategastes sp. 

Unidentified
-
Harpacticoid 
Order Cyclopoida Oi thonidae Oithona colcarva 
Oithona plumifera 
Cyclopidae Cyclopoid copepodids Cyclops sp. Eucyclops agi1 is Eucyclops speratus Halicyclops sp. Hemieye lops sp. Macrocyclops albidus Mesocyclops edax Tropocyclops prasinus 
Clausidi idae 
Saphirella sp. A (narrow) Saphirella sp. B (wide) 
Ergasilidae 
Ergasilis sp. 

Lichomolgidae Lichomolgid A (Cyclopoid commensal) 
Oncaeidae 
Oncaea sp. 

Coryeaeidae 
Corycaeus sp. 

Sabel1iphil idae Sabel1iphilid sp. (Lubbockia) 
Unidenti fi ed Cyclopoid Copepodids Copepod Nauplii (Calanoid, Harpacticoid and Cyclopoid combined) 
Order Caligoida 
Caligidae Caligus sp. metanauplius Caligus sp. 
Argulidae 
Argulus alosae 

Order Thoracica 
Barnacle nauplii Barnacle cypris larvae 
, 
Order Stomatopoda Stomatopod antizoea Stomatopod pseudozoea 
Order Mysidacea  
Mysidae  
Mysidopsis  bahia  
Mysidopsis  almyra  
Mysidopsis  sp.  (juvenile)  

Metamysidopsis swifti 
Order Cumacea Cumacean (Juvenile) Oxyurostylis salinoi Cyclaspis varians 
Order Tanaidacea 
Leptochelia rapax 
Order Isopoda Idoteidae 
Edotea mantosa 
Cymothoidae Aegathoa oculata 
Bopyridae Bopyrid A 
Munnidae 
Munna sp. 
Order Amphipoda Ampeliscidae Ampelisca abdita 
Amphithoidae Cymadusa compta 
Bateidae Batea catharinensis 
Corophi idae Corophium louisianum Corophium acherusiQum 
Gammaridae Gammarus mucronatus 
* 
Microprotopus sp. 
Oedicerotidae Monoculodes nyei 
Caprel1idae Caprellid (immature) 
Order Oecapoda 
Palaemonidae Macrobrachium sp. Zoea Palaemonetes Zoea
sp. Palaemonetes pugio 
A1pheidae Alpheus sp. 
zoea 
Lucifer faxoni 
Lucifer faxoni protozoea 
Penaeidae 
Penaeus aztecus postlarvae Penaeus setiferus postlarvae 
Sergestidae  
Acetes  americanus  louisianensis  
Acetes  americanus  louisianensis  
protozoea  

Ogyrididae Ogyrides limicola Zoea limicola post larvae
Ogyrides 
Callianassidae Callianassa Zoea
sp. Callianassa sp. juvenile Callianassa Zoea #2
sp. Porcellanid Zoea 
Upogebia affinis zoea 
Hi ppolytidae Tozeuma carolinense zoea Hippolyte sp. zoea wurdemanni
Hippolysmata 
Porcel1anidae Petrolisthes armatus zoea Petrolisthes armatus megalops 
Paguridae 
-
Clibanarias vittatus zoea 
zoea
Pagurus sp. 
Glaucothoe larvae 
Portunidae Callinectes spp. megalops Callinectes sapidus 
Xanthidae 
Rithropanopeus harrissi Zoea 
Pi nnotheridae Pinnixa sp. Zoea Pinnotheres sp. Zoea 
Pinnotherid zoea A 
Ocypodidae 
Uca Zoea
sp. 
Unidentifi ed 
Brachyuran Zoea Brachyuran megalops Decapod larvae (Galatheid type) 
Class Insecta 
Order Ephemeroptera 
Insect larvae 

Mayfly larvae 
Order Chironomidae 
Midgefly larave Midgefly pupae 
Class Tardigrada Tardigrade (water bears) 
PHYLUM PHORONIDA Actinotroch larvae 
PHYLUM ECHINODERMATA Ophiopluteus larvae Echinopluteus larvae Bipinnaria larvae 
PHYLUM BRYOZOA 
Cyphonautes larvae A Cyhonautes larvae B 
PHYLUM CHAETOGNATHA  
Saggita  sp.  
PHYLUM  CHOPADATA  
Class  Ascidiacea  
Ascidian  larvae  
Class  Larvacea  
Oikopleura  sp.  
Class  Osteichthyes  
Fish  eggs  

29 
Lavaca Bay  
Table h'.l  Zooplankton  abundance 1984 -1986  
1984-1985 (individuals/m cubed)  
Station  Nov-84  Jan-85 Mar-85 Apr-85 Mau-85  Jun-85  Jul-85  Aug-85  Average  s.d.  
45  379  3018  3294  158  608  279  62  382  1022.5  1328.8  
603  1573  1255  657  66  74  1064  40  808  692.13  591.02  
65  1742  1468  2316  40  200  705  322  548  917.63  824.6  
613  7424  906  1801  2326  8?>.j  1722  568  2279  2232.6  2200.6  
85  3671  3656  1985  14220  2905  7781  2916  2074  4901  4185.4  
623  3938  4515  965  1984  400  24440  3868  1417  5193.1  7923.7  
633  7961  1218  2469  34889  6685  3061  9360.5  12762  
Average  5121.2  2469.7  2713.9  2859.1  1069.9  10126  2065.9  1509.9  3258  
s.d.  2502.1  1470.7  2470.4 5096.7  1139.6  13917  2540  1001.2  5910  
1985 -1986 (individuals/  m cubed)  
Station  Oct-85  Dec-85  Feb-86  Apr-86  Jun-86  Auq-66  Average  s.d.  
45  448  257  11  221  257  63o  304.5  212.66  
605  131  194  179  250  175  533  243.67  146.84  
65  595  267  598  494  57  5553  857.35  1258  
tj1 j  482  1981  234  351  478  12171  2616.2  4725  
85  2847  319  7447  4902  2235  829  3096.5  2677.6  
623  3573  2861  1436  15840  2968  30585  9543.8  11590  
635  102  2407  631  3244  191  28938  5918.8  11349  
1  •5992  4580  77184  9600  12321  21955  31034  
2  7766  15849  20314  10111  9775  12763  5185.4  
3  5963  8093  48821  24971  11601  19890  17781  
1505  38482  12686  53572  31900  22848  11465  25159  1 1 jOj  
1905  20716  7413  20346  22504  16197  20544  17953  5567.1  
35-36  12633  8376 598108  6615  7130  86572  174170  
Average  7980.9  4344.8  37776  18835  7437  11529  14864  
s.d.  1271 1  3985.3 108734  23944  8856.3  9966.3  47071  
Average st 45-653  3226  
s.d.  6798  

30 Lavaca Bay Table 4.3 Zooplankton biomass 1984 1986
-
1984 -1985 (rng dry vt/’rn cubed)  
Station  Nov-84  Jan-85  Mar-85  Apr-85  Maq-85  Jun-85  Jul-85  Aug-85  Average S.d.  
45  1.0  7.0  5.6  2.6  3.2  3.4  1.2  3.0  3.4  2.0  
603  52.1  11.7  6.3  "i r, «.o  2.3  14.6  2.6  3.9  12.7  16.5  
65  15.2  3.2  3.4  5.4  0.6  4.9  2.5  4.9  5.0  4.4  
613  390.2  49.9  8.2  36.8  7.6  8.2  13.0  8.8  65.3  132.2  
85  C O ,j, ij  1 O -7 i i-. i  1.3  69.9  C O , fJ  4c n  23.6  7'/ 1 ¦JiL. i  24.7  23.8  
623  72.0  40.7  38.6  1473.8  24.3  158.8  44.5  1 7 c 1 I.j  233.8  503.0  
633  41.4  355.3  22.1  101.7  17.9  16.6  92.5  132.7  
Average  89.4  20.8  1 5.0  278.8  9.5  48.2  15.0  12.4  61.4  
s.d.  150.0  19.4  17.3  541.7  9.7  60.1  15.6  10.5  208.9  
1 OSC  _  1 U!-!k { rr.i-i Hm •—•4 / rr«  
i  1 j-" *_* KJ  \11  ui y  inf  <<i lr UL".-U/  
Station  Oct -85  Dec-85  Feb-86  Apr-86  Jun-86  Aua-86  Average S.d.  
-1C •-tJ  1.2  1.3  2.2  6.0  0.4  1.0  2.0  2.0  
3.1  0.5  3.6  1.3  0.3  4.7  1 o 1 .'J  
65  1.2  1.0  0.6  6.7  5.4  7.1  .j. .j  2.9  
613  1.8  *7* i .-J  26.7  1.3  2.2  19.2  9.7  10.7  
85  13.3  13.7  2.6  17.0  ¦j.6  22.9  12.2  “i O » .u  
623  12.0  7.5  17.9  55.0  10.7  175.2  46.4  65.5  
633  7.3  27.6  6.7  28.4  6.2  53.9  21.7  18.9  
1  28.0  87.4  308.7  112.8  23.3  112.0  116.4  
9  37.3  21.4  207.3  77 O O-J.U  37.4  67.4  -jo c I u.u  
T  7.8  14.1  220.9  82.9  76.3  80.4  85.8  
1505  18.5  21.6  112.7  O ~r o  3 4.8  54.1  41.7  
1905  25.6  19.8  97.9  56.1  49.1  49.7  31.0  
-~j 5-.j6  43.0  137.1  12.2  2 j.8  54.0  56.8  
Average|  5.7  16.9  27.8  88.6  31.3  40.7  36.9  
a.d.  5.2  14.3  39.8  104.2  39.0  45.7  57.3  
.  
Average  45-633  13.9  
d.  45-s.d.  28.5  
bold =  Detritus in sample  

31  
Lavaca Bag  
Table 4.4  Frcahvntcr zooplankton  abundance 1984-1986  
1984-1985 (individuals/ m cubed)  
Station  Nov-84  Jan-85 Mar-85 Apr-85 Mag-85  Jun-85  Jul-85  Auq-85  Average  s.d.  
45  1.5  2985  3285  148  572  58  50  0.1  887.45  1401.8  
603  1.5  666  558  9  17  25  1.3  0  134.48  247.26  
65  3.4  1352  2096  53  73  0.5  3.5  0  445.18  814.35  
613  0  104  81  41  70  0  1  0  57.125  42.983  
85  0.1  0  45  57  25  0  0  0  15.688  23.542  
623  0.1  1.5  19  56  69  0  0  0  18.2  28.31  
633  5  84  252  0  1  0  57  101.09  
Average  l.l  851.42  641.29  61.143  154 11.643  8.1143  0.0143  234.2  
s.d.  1.3282  1169.9  1314.5  44.771  200.24  22.152  18.507  0.0578  673  
1985 -1986 (individuals/ m cubed)  
Station  Cict-85  Dec-85  Feb-86  Apr-86  Jun-86  Auq-86  Average  s.d.  
45  0.1  159  0.2  0.1  255  0  69.067  111.07  
603  0  61  0  0  0.8  0  10.3  24.84  
65  0  89  0  0  24  0  1 o.Sio  55.69  
615  0  18  0  0  0.1  0  3.0167  7.5404  
85  0  1  0  0  0.1  0  0.1 8-j3  0.4021  
623  0  0  0  0  0  0  0  0  
633  0  0  0  0  0  0  0  0  
1  0  0  0  0  0  0  0  
C­ 0  0  0  0  0  0  0  
3  0  0  0  0  0  0  0  
1505  0  0  0  0  0  0  0  0  
1905  0  0  0  0  0  0  0  0  
35-36  0  0  0  0  0  0  0  
Average  0.01  25.251  0.0154 0.0083  21.538  0  8.222  
s.d.  0.0316  49.136  0.0555  0.0289  70.457  0  36.6!  
Average st 45-653  14.49  
o-.d.  47.89  

Lavaca Bay 
Table 4.5 Surface and bottom standing crop vs stratification 

1985 -1986  Oct-85  Dec-85  Feb-86  Apr-86  Jun-86  Aug-86  
Mean14d flow, cu ft/sec  35  521  43  32  258  15  
Station  
45 Standing crop, surface tow  448  257  11  221  257  633  
45 surface salinity, ppt  4.4  0.9  5.3  13.4  0.6  3.9  
45 surface dissolved Oxygen, mg/I  9.7  9.9  9.5  9.5  8.2  7.4  
45 standing crop, oblique tow  1524  372  264  539  456  2321  
45 bottom salinity, ppt  17.6  2.8  6.8  13.8  18.1  4.4  
45 bottom dissolved Oxygen , rng/1  1.4  9.7  7  9.5  0.3  5.6  
65 Standing crop, surface tow  395  267  598  494  37  3353  
65 surface salinity, ppt  6.9  1.4  8.7  16.1  1  9.4  
65 surface dissolved Oxygen, mg/I  6  10.2  9.8  8.9  8.2  8  
65 standing crop, oblique tow  1721  1287  588  625  2521  8953  
65 bottom salinity, ppt  17.7  8  13.1  17.4  1 8.3  99  
65 bottom dissolved Oxygen, rng/1  4.2  10.1  7.4  8.5  0.3  7.1  

33  
Lavaca Bay  
Table A. 6 Acartia ionsa  abundance 1984-1986  
1984 -1985 (individuals/cu m)  
Station  Nov-84  Jan-85 Mar-85 Apr-85 Mag-85  Jun-85  Jul-85  Aug-85  Average  s.d.  
45  355  17  0  0.1  0  136  4  290  100.26  145.65  
603  1128  119  95  28  19  886  18  568  357.63  444.25  
65  1123  94  32  0  76  124  285  496  278.75  377.54  
613  5646  258  270  846  518  1291  301  2231  1170.1  1207  
85  2590  2265  182  11513  2953  6420  2688  1228  3729.9  5621.3  
623  3283  3639  125  1130  263  1 1092  2740  1185  2932.1  5556.6  
633  424  849  1287  25608  6494  2391  6175.5  9771.5  
Average  2020.8  1065.3  161.14  2052.3  730.86  6508.1  1790  1198.4  1956  
s.d.  1336.9  1526.6  147.05  4198.8  1078.7  9563.2  2403.1  857.21  4088  
1985 -1986(individuals/  m cubed)  
Station  Oct-85  Dec-85  Feb-86  Apr-86  Jun-66  Auq-86  Average  s.d.  
45  327  11  6  15  0.3  55?  153.05  235.59  
603  95  83  11  20  45  479  122.17  177.96  
65  36  148  45  1.1  10  2009  574.52  802.45  
613  432  2845  43  84  408  12242  2675.7  4803.5  
85  1667  2784  228  5602  558  7852  2781.8  2796.1  
623  577  1344  74  1200  221  29542  5493  11793  
64  1922  141  2401  34  28152  5452.3  11168  
1  3597  124  48761  4389  1 1637  13666  20075  
O  4578  22?  29674  1328  8104  8742.2  12094  
T  3095  353  30522  19917  9387  12655  12504  
1505  27448  4855  1700  22269  11468  8618  12725  10101  
1905  8855  5437  104  14690  10559  14157  8633.7  5843  
55-36  5529  5085  974  4437  543  3313.6  2369.5  
Average  4503  2566.5  310  12772  4105.7  10252  5707  
s.d.  8583.1  1757.8  489.3  16421  6203.5  9483.1  9532  
Average ?t 45-635  2436  
o V .d.  6397  

34 
Lavaca Bay 
abundance 1984-1986
Table 4.7 Mnemiopsis mccradyi 
-
1984 1985(volume ml/cum) 
Station Nov-84 Jan-85 Mar-85 Apr-85 Maq-65 Jun-85 Jul-85 Auq-85 Average s.d. 
451.5 0 0 0 0 0 0 00.16250.4596 
603	00000000 00 65000000070.4 8.824.89 
615 0 0 0 0 0 0 6.8 27 4.2259.5051 
85 0 0 0 0 0 0 48 54 12.75a.0.t*t?3 623 0.4 0 0 0 0 0 6.7 0.2 0.9125 2.343 635 0 0 0 0 0 0 5.1 40 5.637513.999 
Average 0.2429 0 0 0 0 0 9.5145 27.571 4.641 
s.d. 0.4894 0 0 0 0 0 17.26 28.743 	14.41 
-
1985 1986(volume ml/cu m) 
c-v'.U
Station Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 	Average A. 
45 0 0 0.2 0 0 0 	0.0535 0.0816 
oo
605 0 1.9 0 0 0 0.6833 1.0629 65 0 1.7 0.5 0 0.1 0.1 0.3667 0.6623 613 4.5 0 1.5 0 0.2 0 1 1.7877 , 85 20 5.3 0 1.3 0.7 42 11.55 16.696 623 19.5 10.2 0.1 0.1 0 0 4.9833 8.1891 633 80 13.4 C 1.5 0.6 0 16.25 31.628 
1 0.7 0.1 16 0.1 11 	5.58 7.4469 

2 0.8 0.1 82 0.1 159 	34.4 60.06 


T 
0.2 0.1 0 0 IS 3.6*6 8.0167 1505 0.5 0.2 0.8 2.3 0.1 29 5.4855 1 1.548 1905 0.6 0.5 0 17 0 14 5.35 7.9231 
35-36 0.5 0 2.6 0.1 0 	0.64 1.1149 
Average 12.78 2.5585 0.7308 5.85 0.1538 19.469 	6.697 
TO TA
s.d. 24.884 4.5995 0.9096 10.305 0.2295 JM 	19.71 
. 
Average st 45-655 4.981 
s.d. 14.19 
Lavaca Bay Table 4.8 Dominant zooplankton Spatial distribution
-
October 85  Individuals / m‘ 3  
Station  45  65  85  1  2  3  1505  1905 35-36  
Nautical miles  0  4.4  9  10.7  12  13.6  15.4  18.6  24  
Salinity, ppt  4.4  6.9  20.5  28.7  29.2  32.6  
Freshvater spp.  0.1  
Estuarine spp.  
Barnacle nauplii  108  352  303  103  211  72  
Acartia tonsa  327  36  1667  27448  8855  5529  
Paracalanus crassirostris  2  0.1  575  806?  6476  2957  
Pseudodiaptomas coronatus  0.1  0  0.1  29  301  5  
Oithona colcarva  3  0  125  1134  2289  457  
Marine spp.  
Saqitta  spp.  0  0  0  99  78  173  
Oikopleura spp.  0.1  0  117  825  1296  2620  
Noctiluca scintillans  0  0  0  0  0  0  
December 85  IndividualIs / nT3  
Station  45  65  85  1  ?  3  1505  1905 35-36  
Nautical miles  0  4.4  9  10.7  12  13.6  15.4  18.6  24  
Salinity, ppt  0.9  1.4  8.2  10  12  12  18.7  20.3  22  
Freshvater spp.  236  88  1  0  0  0  0  0  0  
Estuarine spp.  
Barnacle nauplii  3  18  925  904  1089  1204  5715  736  74  
Acartia tonsa  11  148  2784  3397  4378  3095  4835  3437  5085  
Paracalanus crassi rostris  0  0  7  199  289  363  1489  859  751  
Pseudodiaptomas  coronatus  0  0  43  884  833  248  369  450  244  
Oithona col carva  0  0  139  407  756  525  1523  1227  1748  
Marine spp.  
Sagitta spp.  0  0  0  0.6  2.1  1.4  73  7  28  
Oikopleura spp.  0  0  0  0  9  0.4  7  19  127  
Noctiluca sci ntillans  0  0  0  0  0  0  0  0  0  

Lavaca Bay Table 4.9 Dominant zooplankton Spatial distribution
-
February 86  Individuals /m'‘3  
Station  45  65  85  1  2  3  1505  1905  55-56  
Nautical miles  0  4.4  9  10.7  12  13.6  15.4  18.6  24  
Salinity, ppt  5.5  8.7  13.1  9.2  15  20  14.4  18.2  20.4  
Freshvater spp.  0  0  0  0  0  0  0  0  0  
Estuarine spp.  
Barnacle nauplii  1.4  534  7120  3766 15267  7513 13733  2374  8737  
Acartia tonsa  8  43  228  124  227  353  1700  104  974  
Paracalanus crassirostris  0  0  4  0.5  0.6  22  80  10  257  
Pseudodiaptomas coronatus  0.1  0.1  0.4  102  58  0.3  47  7  79  
Oithona colcarva  0  0.4  47  43  62  58  713  176  1605  
Saltvater spp.  
Saqitta spp.  0  0  0  0  0  0.3  0.8  0.1  0  
Oikopleura spp.  0  0  0  0  0  0  0  T  79  
Nocti 1 uca sci nti 11 ans  0  0  0  0  0  0.1 17067 17463 oS5368  

April 85  Individuals /nT3  
Station  45  65  85  1  2  3  1505  1905  35-36  
Nautical miles Salinity, ppt  0 13.4  4.4 16.1  9 23.9  10.7 26  12 26  13.6 27.3  15.4 27.9  18.6 28.4  24  
Freshvater spp.  0  0  0  0  0  0  0  0  
Estuarine spp. Barnacle nauplii Acartia tonsa Paracalanus crassirostris Pseudodiaptomas coronatus Oithona colcarva  198 15 0 0.1 0  469 1.1 0 0.7 0  847 24573 6250 10522 1111 1083 3602 48781 29674 30522 22269 14690 0.1 31 16 299 417 0 0.1 549 380 746 324 57 3 165 125 224 602 412  
Saltvater spp. Sagitta spp. Oikopleura spp. Hoctil uca sci ntilIans  0 0 0  0 0 0  0 149 0  1.2 427 0  0.1 1957 0  0.7 746 0  0.7 926 0  0.5 1083 155  

Lavaca Bay 
-
Table 4.10 Dominant zooplankton Spatial distribution 
-
June 86 Individuals / m‘3 
Station 45 65 85 1 2 5 1505 1905 35-36 
Nautical miles 0 4.4 9 10.7 12 15.6 15.4 18.6 24 Salinity, ppt 0.6 1 18.9 21.8 20.7 26 26.7 27 28.1 
Freshwater 255 24 0
spp. 
Estuarine spp. 
Barnacle nauplii 0.5 0.9 1460 1727 3379 672 707 446 269 
Acartia tonsa 0.3 10 558 4389 1328 19917 11468 10669 4457 
Paracalanus crassi rostris 0 0 1.3 0 4 168 271 670 495 
Pseudodiaptornas coronatus 0 0 0.4 809 601 378 1848 580 44 
Oithonacolcarva 0 0 0.4 0 4 166 217 179 124 
Saltvater spp. 
Saqittaspp. 0 0 0 0 00.8 5 27 2 
Oikopleura spp. 0 0 0.4 4 8 210 2005 446 3 
Noctiluca scintillans 0 0 0 0 0 0 0 0 0 
August 86 Individuals /m‘3 
Station 45 65 85 1 2 3 1505 1905 35-56 
Nautical miles 0 4.4 9 10.7 12 13.6 15.4 18.6 24 Salinity, ppt 3.9 9.4 11 16.1 18.7 21.5 24.2 26.1 o5.o 
Freshwater 000000000
spp. 
Estuarine 
spp. Barnacle nauplii 41 403 292 303 1485 434 293 107 0 Acartia tonsa 557 2099 7852 11637 8104 9383 8618 14157 543 Paracalanus crassi rostris 0 0.1 1.5 3 0 124 150 656 509 Pseudodiaptomas coronatus 0 3 5 61 0 433 520 1406 8 
Oithona colcarva 0 0 31 76 6 247 553 1594 335 
Saltvater spp. 
Sagittaspp. 0 0 0 0 0 0.4 0 2.6 1.6 Oikopleura spp. 0 0 0 0 0 62 96 250 5 Noctiluca scintillans 0 0 0 0 0 0 0 0 0 
CHAPTER 5 
BENTHOS 
INTRODUCTION 
Benthic macrofauna consisting primarily of polychaete worms, molluscs, 
and small crustaceans are secondary producers associated with the sediment. 
These organisms transfer energy from the primary producers, i.e. bacteria, 
microphytobenthos, and the phytoplankton, to higher trophic levels. The 
benthic macrofauna in the upper Lavaca Bay during this study was limited to a 
few dominant organisms consisting of the polychaetes, Mediomastus 
californiensis and Streblospio benedicti, Chironomid midge fly larvae, and the 
molluscs Macoma mitchelli and Mulinia lateralis. A list of species collected is 
given in Table 5.1. 
METHODS 
Benthic core sampling was accomplished using SCUBA or snorkeling. 
Triplicate samples were collected at each site with 7.5 cm diameter, 30 cm long 
aluminum cores which were capped and placed upright in a bucket of ambient 
water. The walls of each sediment core were split to aid in sectioning the 
sediment horizontally by depth. 
Each core was sectioned at the following depths; 0-3, 3-10, and 10-20 
cm. Sections were placed in a 1 liter jar and preserved with 10% formalin in 
seawater stained with rose bengal. In the lab, each sediment section was 
sieved through 0.5 mm mesh and the retained organisms were identified and 
counted. Wet weight biomass was measured on dominant individuals and on the 
entire sample. 
2 
The effect of freshwater inflow of Lavaca Bay benthos was determined by 
analyzing bay wide abundance and biomass with physical parameters, i.e.,
7 
salinity and temperature (Table 5.2). The “x 14 day Lavaca River streamflow 
rate calculated from the U.S. Geological Survey data from streamflow gauge 
number 08164000 near Edna, Texas was also used. The x 14 day flow period 
was chosen to assess the impact on recent flow regimes on the fauna. Lagged 
effects of flow were also examined. For example, benthic reproduction and 
migration time is on the order of 1 month and a flow event may not result in 
measurable short term changes in the benthic community. Pearson Correlation 
Coefficients were calculated for benthos with salinity, temperature, x 14 day 
flow and the x 14 day lag flow. The lag flow was achieved by shifting the 
flow data forward by one sampling trip. Since Table 5.2 contains 50 
correlation tests, it is prudent to take the Bon Ferroni approach and reject at 
=
P 0.001 (i.e., .05/50). 
RESULTS 
Distribution Patterns 
The benthic community in Lavaca is typical of a low to
upper Bay 
moderate salinity environment with only a few dominant species. Very little 
in total benthic faunal abundance between Year and
change was seen the 1 
Year 2, but stations 623 and 633 had an abundance increase in Year 2 
(Table 
5.3). Monthly standing increases were evident in March, and June 1985
crop 
and in February and April 1986. No significant calculations were found with 
faunal abundance and any of the physical parameters measured (Table 5.2). 
The distribution of infauna by depth in the sediment typical for
was most 
estuaries. Highest concentrations of organisms were found in the upper 0-3 
cm, decreasing with' depth with the lowest numbers found in the 10-20 cm core 
sections (Table 5.3, Fig. 5.1). Average abundance within sections was similar 
for both 
years. 
Benthic biomass was in direct contrast to the abundance distributional 
patterns (Table 5.4, Fig. 5.2). Average biomass comparisons indicates an 
overall increase in biomass for Year 2. Biomass increases occurred from March 
through June 1985, August 1985, and February through August 1986. Biomass 
measurements, unlike individual abundance, increased with depth. The largest 
biomass the 10-20 cm depth The biomass at each depth was
range. average 
greater in Year 2. Benthic biomass was positively correlated with salinity; r = 
0.70820** (Table 5.2). 
When molluscan biomass was examined and compared to the total benthic 
biomass a similar pattern was obvious which indicated that any distributional 
trends in the total biomass data were most likely due to the mollusc weights 
(Table 5.5 and Fig. 5.3). Mollusc biomass measurements are indicative of a 
larger mollusc population during low inflows. Weight increases were evident, 
especially in the 3-10 and 10-20 cm sections in Year 2. An increase occurred 
in the 10-20 cm section from April through June 1986. Mollusc biomass also 
had a positive correlation with salinity, r = 0.73330** (Table 5.2), 
Benthic biomass minus the mollusc biomass results in a biomass comprised 
mainly of polychaetes, chironomids, and a few crustaceans (Table 5.6 and Fig. 
5.4). This distribution indicates no response to freshwater inflow, which was 
confirmed by correlation coefficient calculations (Table 5.2). Seasonal highs 
are evident in January through April 1985, and December through June 1986. 
A longer term data base would be necessary to verify this apparent seasonal 
pattern. 
Species Distributions 
Chironomid midge fly larvae was one of the benthic species that had a 
response related to freshwater inflow (Table 5.7 and Fig. 5.5). Adult midge 
flies are terrestrial while their larvae are associated with freshwater systems. 
When their abundance is correlated with streamflow, there is a lag response 
=
which is apparent the month following an inflow event, r 0.84126*** (Table 
5.2). They are concentrated mainly in the upper 0-3 cm of sediment and, as 
with freshwater zooplankton species, they are good indicators of freshwater 
influence. Their distribution is mainly restricted to the Lavaca River (stations 
45 and 65), lakes (stations 603 and 613), and stations 623 and 633 which are 
associated with inflow from Venado Creek and Garcitas Creek. Higher numbers 
and wider distributions in Year I are evidence of high inflow during this 
period. 
The polychaete, Streblespio benedicti is a surface dwelling suspension,
, 
deposit feeder which increased in density increase during low flow periods 
(Table 5.8, and Fig. 5.6). Its lowest density was during high inflow events and 
its lowest density during both years was at station 45 upriver. The correlation 
=
coefficient of S. benedicti abundance versus salinity was significant, r 
0.55725* (Table 5.2). The few incidental occurrences in the 0-20 cm core 
sections are indicative of its preference for the surface sediments. 
Mediomastus califoriensis is a burrowing polychaete, distributed 
throughout the sediment to at least a depth of 20 cm (Table 5.9 and Fig. 5.7). 
Densities, as with Streblospio benedicti, increased during February-June 1986. 
Significant correlation was calculated for M. califoriensis versus salinity, r = 
0.74885** (Table 5.2). Comparable densities were found in sections 0-3 and 3­
stations 85 and 623 in
10 cm with a decline below f 0 cm. At May through 
August 1985 and at stations 85, 613, 623 and 633 in June and August 1986 
there was an increase in density in the 10-20 cm depth sections which may be 
related to the burrowing activity of the bivalve Macoma mitchelli which was 
abundant. 
Two polychaetes which were not numerically dominant, Hobsonia florida 
and Laeonereis culveri occurred throughout most of the study
, sporadically 
(Tables 5.10 and 5.11). Hobsonia florida had a preference for surface 
sediments while L. culveri was found at all depths sampled. Highest densities 
of H. florida corresponded to Year 1 during high flows and had a significant 
correlation with the x 14 day lag flow, while L. culveri densities increased 
only slightly in Year 2. 
The two molluscs which comprised most of the benthic biomass were 
Mulinia lateralis (Table 5.12 and Fig. 5.8) and Macoma mitchelli (Table 5.13 and 
Fig. 5.9). While both species were present in Year 1 during high inflows, their 
peaks in abundance occurred in February and April 1986. Mulinia lateralis is a 
surface dweller with most of its numbers and biomass in the upper 0-3 cm. 
When Macoma mitchelli first settles in the benthos it is found in the surface 
sediments as illustrated in December 1985 and February 1986 (Table 5.10). As 
Macoma matures, its numbers decline due to natural mortality, and it begins to 
burrow deeper in the sediment. It ultimately leaves the surface and most 
individuals are found in the deeper sediment. Deep burrowing activity of 
Macoma may be important in increasing available habitat to other small 
burrowing infauna, i.e. Mediomastus califoriensis. Although density peaks were 
high for both Mulinia and Macoma during low flow periods, longer term 
sampling is necessary to describe annual cycles in relation to inflow events. 
CONCLUSIONS 
Benthic communities in Lavaca varied between the two
upper Bay years 
but it is difficult to relate these variables to freshwater inflow. The only 
species which were affected by inflow on a short term was the aquatic 
chironomid larva and Hobsonia florida which had a lag response to inflow. 
The molluscs, Mulinia lateralis and Macoma mitchelli both increased in the low 
flow period which resulted in higher benthic-biomass. Once these effects were 
separated from the rest of the benthos no apparent differences between the 
two years were discernable. 
Higher biomass in Year 2 was a result of increased mollusc populations 
while the remaining biomass for the rest of the benthos was similar in Year 
and 2. Lower density and higher biomass in the deeper sediment indicates that 
most of the deep burrowing infauna are large individuals. 
some
Although distributional patterns were apparently related to 
fluctuations in freshwater inflow, longer term monitoring is necessary to 
distinguish between seasonal cycles and freshwater inflow events. 
7 
combined stations 
All 
sampling 

by 
flow 
stream average 
day 
14 
vs 
average 

crop 
standing 
Benthos 

5.1. 
Figure 
sediment 

by 
abundance denotes Stippling 
1986. August through 
1984 
November 

from trip 
10-20. 

and 
3-10, 0-3, 
depth: 
8 
1984 
sediment

November 

by 

) 
(mg/m
trip 
weight
sampling 

wet 
by biomass
streamflow 

denotes 

average 

Stippling

day 
14 vs 
1986. 
biomass August Benthos through 
5.2. 
Figure 
cm. 
10-20 
and 
3-10, 0-3, 
depth: 
9 
denotes 
Stippling 

trip. cm. 
10-20
sampling 

and 
by 3-10, 
0-3,
streamflow 

depth: average day sediment 
14 by 
) 
ys 
(mg/m
biomass 
weightMollusc wet 
5.3. 
Figure 
10 
trip(mg/m2) sampling weight 
by wet 
biomass

streamflow 
denotes 
average 
day 
Stippling

14 
cm. 
vs 
1986. 10-20biomass andAugust 3-10,
mollusc 
through 0-3,minus 1984 depth:
biomass 
November 

sediment
Benthos from by 
5.4. Fig. 
combined stations 
All 
from trip 
sampling 

by 
streamflow 

average 

day 
14 vs 
abundance/m2 

average 

Chironomid 

5.5. 
Figure 
depth: 
sediment 

by 
abundance 
denotes 
Stippling 

1986. August through 
1984 
November 

11 
cm. 
10-20 
and 
3-10, 0-3, 
12 
sampling 

by 
streamflow 

average 

day 
14 vs 
abundance/m2 

average 
henedvcti, 
Streblospio 

5.6. 
Figure 
sediment 

by 
abundance denotes Stippling 
1986. August through 
1984 
November 

from trip 
cm. 
10-20 
and 
3-10, 0-3, 
depth: 
13 
combined stations 
All 
by 
streamflow 

average 

day 
14 vs 
abundance/m2 

average 
californiensis 
Mediomastis 

5.7. 
Figure 
abundance denotes Stippling 
1986. August through 
1984 
November 

from trip 
sampling 

cm. 
10-20 
and 
3-10, 0-3, 
depth: 
sediment 

by 
14 
sampling 

by 
streamflow 

average 

day 
14 
vs 
abundance/m2 

average 
lateralis 
Mulinia 

5.8. 
Figure 
by 
abundance 
denotes 
Stippling 

1986. August through 
1984 
November 

from trip 
cm. 
10-20 
and 
3-10, 0-3, 
depth: 
sediment 

15 
trip 
sampling 

by 
streamflow 

average 

day 
14 vs 
abundance/m2 

average 
mitchelli 

Maooma 
5.9. 
Figure 
sediment 

by 
abundance denote? Stippling 
1986. August through 
1984 
November 

from 
cm. 
10-20 
and 
3-10, 0-3, 
depth: 
Table 5.1. Lavaca Bay Macrobenthos Species List, November 1984-August 1986 
PHYLUM PLATYHELMINTHES Flatworms (unidentified) 
PHYLUM NEMERTINIA (=Rynchocoela) Nemerteans (unidentified) 
PHYLUM MOLLUSCA 
Cl ass Gastropoda 
Pyramidel1idae Odostomia laevigata Odostomia cf. gibbosa 
Acteonidae 
Acteon punctostriatus 
Class Pelicypoda 
Solenidae 
Ensis minor 

Tel 1inidae Macoma mitchelli 
Macoma tenta 
macoma 
sp. 
Mactridae Mulinia lateralis Rangia 
cuneata 
Solecurtidae Congeria leucophaeta Tagelus plebius 
PHYLUM ANNELIDA 
Class Polychaeta 
PhylIodicidae 
Eteone heteropoda 
Pi 1argi idae 
Sigambra tentaculata 

Ancistrosyl1 is jonesi Loandalia americana Parandalia 
-
sp. 
Pilargidae unidentified 
Hesionidae 
Gyptis vittata 
Neriidae 
Nereid juvenile Laeoneris culveri Neanthes succinia 
Glyceridae Glycera capitata 
Spibnidae Polydora social is 
„ 
Streblospio benedicti Scolelepis 
texana 
Cossuridae 
Cossura delta 
Orbinidae 
Haploscloplos foliosus 
Capitel 1idae Capitella capitata Mediomastus californiensis 
Heteromastus filiformis 
Ampharetidae Hobsonia florida 
Cl ass 01igochaeta Oligochaetes (unidentified) 
Cl ass Hi rudi nea 
Leeches (unidentified) 
PHYLUM ARTHROPODA 
Cl ass Crustacea 
Subclass Copepoda 
Order Cyclopoida Cyclopidae Hemieye lops sp. 
Lichomolgidae Cyclopoid copepod (commensal) 
Subclass Malacostraca 
Order Mysidacea Mysidopsis sp. juvenile Mysidopsis almrya 
Order Cumacea 
Cyclaspis varians Cumacean unidentified 
Order Tanaidacea 
Tanaidae 
Leptochelia rapax 
Order Isopoda Idoteidae 
y 
Edotea montosa 
Order Amphipoda Ampeliscldae Ampelisca abdita 
Oedicerotidae Monoculodes nyei 
Corophiidae Corophium louisianum 
Order Decapoda suborder Reptantia Callianassidae 
Callianassa juvenile Callianassa jamaicense Callianassa latispina 
Portunidae Callinectes sapidus 
Class Insecta Insect larva (unidentified) Order Di ptera 
Chironomidae Chironomid larva Chironomid 
pupa Table 5.2. Pearson correlation coefficients (r values) for Lavaca Bay benthos monthly means for all stations and sampling trips, r values without * indicates the correlation is not significant. 
Lag Flow 
x Salinity 
x Temperature 
2 
Standing crop/m 
Total Biomass/m2 
Mollusc Biomass/m2 
Total Biomass minus Mollusc Biomass 
Chironomid Larvae 
Streblospio benedicti 
Mediomastus californiensis 
Mulinia lateralis 
Macoma mitchelli 
Hobsonia florida 
Laeonereis culveri 
* 
.05 < P <0.01 **0.01 <P<0.001 *** 0.001 0.0001
<P< 
Lavaca River 
x 14 day Stream Flow 
-0.04769 
-0.55474* 
-0.13715 
-0.18115 
-0.18946 
-0.20574 
0.10491 
-0.02554 
-0.35877 
-0.07520 
-0.08770 
-0.12045 
0.27929 
-0.29870 
x 14 day x Salinity x Temp, Lag by Trip by Trip
Flow 
' 
-0.39186 
0.18238 0.35454 
0.11435 0.50946 0.11346 
-0.11796 0.70820** 0.41330 
-0.11272 0.73330** 0.47492 
-0.05955 -0.10174 -0.44063 
0.84126*** -0.48240 0.07840 
-0.38948 0.74885** 0.02836 
-0.14925 0.55725* 0.03951 
0.03833 0.33979 -0.08005 
-0.01789 0.25877 -0.20552 
0.78998*** -0.46502 0.13728 
-0.44134 0.82217** 0.26598 
Lavaca Bay 
Table 5.3.  B«atha«  crop  la4ivi<tual«/m~2  20  
Totals  
year 1  Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85  Average  s.d.  
45  1285  10042  4984  611-6  1435  10269  6040  3549  5465  3226  
603  5889  2794  3549  7777  2417  5437  1360  1133  3795  2377  
65  4229  4530  6795  5437  7701  9287  7551  5588  6390  1631  
.  
613  378  1057  2718  1586  1813  4229  4833  2945  2445  1394  
85  8533  8985  7702  6116  7551  8079  7475  5814  7532  1100  
623  5134  7853  13214  7777  11024 :  7550  6720  8305  8447  2324  
655  0  0  5739  5210  1588  2190  1284  2794  2351  2095  

Average 3635 5057 6586 5717 4790 6720 5038 4504 5203 
s.d. 3189 3981 3474 2090 3894 2689 2700 2404 3094 
gear 2 0ct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-66 Average s.d. 
45 1511 1058 6041 5890 2719 4758 3663 2196 603 1511 5247 3020 7248 2114 906 3008 2258 
65 5966 5892 12005 14422 12554 2719 8925 4675 613 1963 2039 11476 7778 6871 2719 5474 3875 
85 3549 2114 6040 14572 7626 5814 6619 4558 625 17668 9061 16988 9967 9438 6871 11666 4516 633 680 5437 15629 13968 10721 2416 8142 6204 
4693 4121 10171 10549 7432 5743 6785
Average 
s.d. 5987 2822 5269 3730 3910 2122 4837 
-
0 3cm 
year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 
45 982 9664 4908 5663 1208 10193 3775 2492 4861 3419 603 5456 2492 3247 7399 2341 4606 755 831 3588 2325 65 3096 3171 4530 4606 5587 8532 5814 5171 4813 1850 613 227 755 1963 755 1133 2492 3851 1737 1614 1106 
85 4757 7248 6569 4379 5096 4983 4228 2567 4728 1708 623 4681 4379 9589 5889 6418 2114 2645 2567 4785 2701 635 4153 2114 1135 1455 1284 2265 2064 1120 
Average 3197 4618 4994 4401 2988 4908 3193 2235 3813 
s.d. 2163 3286 2475 2286 2198 3338 1761 750.9 2438 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 1435 831 3096 5512 2341 4304 2920 1765
-
603 906 2794 2718 6342 1510 755 2504 2072 
65 4153 3929 7248 8381 10344 1661 5953 3244 613 1661 1888 7248 .4002 2416 1133 3058 2275 
85 2341 1812 4832 7701 2643 1510 3473 2379 623 14345 8305 14647 4379 4455 2869 8167 5223 633 529 5361 12835 12080 5587 1963 6393 5091 
Average 3624 3560 7518 6914 4185 2028 4638 
s.d. 4873 2575 4638 2789 3056 1205 3766 
Lavaca Bay 
Table 5. 3 (Cont. ) Benthos standing crop lndividuals/m~2 
3-10  cm  
year 1  Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85  Average  s.d.  
45  227  227  76  302  227  76  2114  1057  538.3  754.4  
603  302  302  302  378  76  755  529  302  368.3  213.5  
65  906  1208  1661  453  2114  604  1661  2190  1350  .687.5  
613  151  302  604  831  604  1586  906  1057  755.1  410.1  
85  3398  1586  1133  1586  4228  2869  2869  2794  2558  1069  
623  453  3247  3398  1586  4304  5134  4077  4681  3360  1173  
635  1586  1510  455  755  0  378  780.3  641.9  

Average 906.2 1145 1251 949.4 1715 1683 1737 1780 1410 
s.d. 1250 1173 1126 595.9 1867 1770 1418 1571 	1356 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. ; 45 76 151 2669 302 302 378 679.7 1078 
¦ 	603 529 455 302 906 604 151 490.8 260.5 65 1586 1963 4579 5965 2114 982 2832 1921 
615 302 151 4228 2945 2869 906 	1900 1676 
85 1208 302 1208 6418 4681 3851 2945 2405 623 3247 680 2341 4908 4681 3700 3260 1577 635 151 0 2794 1586 5154 453 1666 1992 
Average 1014 528.6 2589 3290 2912 1489 	1970 
s.d. 1134 671.1 1484 2490 1999 1590 	1872 
10-20 cm year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Awrage s.d. 45 76 151 0 151 0 0 151 0 66.13 80.71 603 151 0 0 0 0 76 76 0 o7.8857.08 65 227 151 604 378 0 151 76 227 226.8 204.5 613 0 0 151 0 76 151 76 151 75.63 67.9 
85 378 151 0 151 227 227 578 455 245.6 151.1 625 0 227 227 302 302 302 0 1057 302.1 331.5 633 0 0 0 1586 0 0 0 151 217.1592.6 
Average 118.9 97.14 140.3 366.9 86.43 129.6 108.1 291.3 167.3 
s.d. 143.8 94.76 224.1 555.7 126.6 113 129.8 371 	268.1 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 	Average s.d. 
45 0 76 76 76 76 76 : 63.3531.05 603 76 0 0 0 0 0 12.6731.03 65 227 0 378 76 76 76 138.8 138.6 613 0 0 0 831 1586 680 516.2 643.4 
85 0 0 0 453 302 453 201.3 227.3 623 76 76 0 680 302 302 239.3 250.1 633 0 76 0302 0 0 63121 
Average 54.14 32.57 64.86 345.4 334.6 226.7 	176.4 
s.d. 84.22 40.62 141 322.9 566.5 261.6 	307 
Lavaca Bay 
Table 5.4. Benthic biomass jig vet vt/m~2 Totals year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 
45 6349 10601 1925 2945 771? 3413 3020 687 4578 3522 603 5373 3277 2870 6946 1133 1488 816 506 2801 2243 65 14783 3775 13567 26727 19337 4093 4402 5904 11324 9283
. 
613 348 2363 30379 6130 3043 27911 2454 3095 9465 12638 
85 3254 8623 13492 11975 30834 1E+05 4952 1570 22757 37272 623 3142 17811 55546 36685 46720 9951 28222 3E+05 57720 88796 635 0 0 36927 55235 48781 19902 8985 34294 22766 17158 
Average 4750 6636 22101 17802 22509 24873 7550 43963 18773 
s.d. 5006 6142 19709 14048 20043 37636 9468 97642 38309 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 
45 2024 9017 27730 26063 3587 1986 11735 12035 603 1035 959 1948 4138 2159 747 1831 1266 65 2250 53234 12949 1E+05 81537 54500 45207 40726 613 763 1578 18905 1E+05 3E+05 29679 74385 1E+05 85 1314 1057 46236 1E+05 1E+05 2E+05 75457 70215 623 14068 20506 39713 1E+05 13643 6200 39964 53014 633 816 16482 40555 96745 23496 890 29831 56029 
Average 3181 11835 26862 92865 68970 34925 39773 
s.d. 4855 12263 16362 56269 90819 61499 57529 
0  -3 cm  
year 1  Nov-84 Jan-85  Mar-85 A pr-85  May-85 Jun-85  Jul-85 Aug-85  Average  s.d.  
45  1306  2514  1895  2069  1601  3224  1155  498  1783  889.9  
603  1344  2205  1435  6463  944  1050  619  317  1797  2118  
65  438  2522  6251  3179  17418  5058  3352  1933  4769  5478  
¦  615  8  1638  8129  2008  491  8818  1510  664  2908  3565  
85  1356  7694  10094  6146  3835  2469  752  672  4122  3597  
625  2575  4047  17207  6070  2643  566  21238  35598  11243  12809  
633  14058  6584  1963  264  8985  461  5386  5510  

Average 1168 3437 8438 4646 4128 2778 5570 5755 4542 
s.d. 887.3 2233 5887 2125 5963 2917 7590 13160 6348 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 355 644 6922 17546 657 1102 4538 6847 603 589 642 1608 2356 287 619 1017 794.6 65 1019 1389 7943 6644 2711 1450 3526 3002 613 559 1434 6455 1993 642 196 1880 2335 
85 385 853 26863 4409 914 619 5674 10488 623 2977 8396 27475 2401 1155 914 7220 10290 633 544 4153 24458 54519 1699 649 14337 21717 
Average 918.3 2502 14532 12838 1152 792.7 5456 
s.d. 933.4 2872 11193 19172 820.5 404 10432 
Lavaca Bay 
Table 5. 
4(Cont.) Benthic biomass ug vetvt/m*2 
23 
3-10 cm 
year  1  Nov-84 Jan-85  Mar-85 Apr-85 May-85 Jun-85  Jul-85 Aug-85  Average  s.d.  
45  4590  914  30  793  6116  189  581  189  1675  2167  
.  
603  4021  1072  1435  453  189  166  189  189  964.3  516.4  
65  14322  951  7029  17093  1896  1012  1050  740  5512 •  6085  
613  340  725  16157  4122  2446  1253  649  2242  3492  5520  
85  1465  838  3398  5640  3050  31937  4062  196  6323  11144  
623  559  4832  30766  446  13877  4115  6946  10230  8971  10067  
653  22869  23805  46816  19638  0  4916  19674  16547  

4216 1555 11669 7479 10627 8330 1925 2672 6177
Average 
s.d. 5259 1609 11835 9284 16584 12513 2604 3754 9695 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Ayg-86 Average s.d. 45 1669 2778 2556 2741 1865 378 1965 898 605 446 272 340 1782 1835 68 790.5 798.3 65 1231 1744 5006 77795 76957 15749 29747 57265 613 189 144 12450 40060 80483 748 22346 32379 85 929 151 19373 92563 23911 4825 23625 35186 623 10676 1872 12238 12095 11982 4908 8962 4457 653 272 68 16097 40135 21737 241 15092 16212 
Average 2202 1004 9694 38167 51255 3845 14361 
s.d. 3775 1105 7212 36045 33559 5667 24358 
10-20 cm year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 45 453 7173 0 53 0 0 1284 0 1120 2670 
605 8 0 030 0272 8 0 59.75101 65 25 302 287 6455 23 23 0 1231 1043 2362 613 0 0 6093 0 106 17840 295 189 3065 6703 
85 455 91 0 189 23949 72948 158 702 12511 27454 625 8 8932 7573 30169 30200 5270 38 2E+05 37506 78089 633 0 2846 0 0 0 28917 5294 11629 
Average 157.5 2750 1993 5677 7754 13765 254.7 35556 8749 
s.d. 229 414? 5335 11063 13321 26899 466.9 81086 31475 
gear2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 0 5595 18452 5776 1065 506 5232 6961 
603 0 45 0 0 37 60 23.67 26.96 65 0 50101 0 22733 1669 17101 11934 13142 613 15 0 0 99449 2E+05 28735 50160 71366 85 0 53 0 31808 79856 2E+05 46158 66192 
623 415 10238 0 1E+05 506 378 23783 52753
: 
633 0 12261 0 2091 60 0 2402 4901 
Average 61.43 8328 2636 41859 36565 30287 19956 
s.d. 156 10856 6974 52271 66918 60551 43649 
Lavaca Bay 
Table 5.5.  Mollusc biomass  ug vet vt/m~2  24  
Totals  
uear 1  Nov-84 Jan-85  Mar-85 Apr-85 May-85  Jun-85  Jul-85 Aug-85  Average s.d.  
45  0  0  0  0  0  0  0  0  0  0  
603  0  0  324.7  0  0  0  0  0  40.58  122.7  
65  0  226.5  3035  9226  15681  566.3  0  1125  3733•  5979  
613  0  2001  23669  5187  1865  25783  0  0  7313  11331  
85  52.85  883.4  6674  9596  26621  98429  45.3  105.7  17801  35683  
623  7.55  649.3  21216  3299  38890  173.7  19728  5E+05  41941  90890  
633  0  0  28101  15440  46697  19132  709.7  27575  1 7206  16475  

Average 8.629 537.1 11860 6107 18536 20585 2926 40053 12576 
s.d. 19.7 734.5 12036 5662 19347 35948 7414 93824 36497 
uear 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 0 0 014028 0 0 2co8 5727 603 0 0 0 286.9 0 0 47.82 117.1 65 0 211.4 6667 93809 75039 51582 34551 40768 613 0 75.5 15645 1E+05 2E+05 27165 70187 1 E+05 85 0 52.85 36572 1E+05 98501 2E+05 69879 68050 
623 0 0 22975 1E+05 0 0 26487 54405 633 0 717.5 59230 91529 528.5 75.5 25347 40079 
0 151 19869 84005 60175 3194? 32691
Average 
s.d. 0 260.8 21758 55390 92314 60212 57147 
-
0 3cm 
gear 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 4500000000 00 605 0 0324.7 0 0 0 0 0 40.58122.7 
65 0 226.5 2673 1374 15681 566.5 0 1102 2703 5625 613 0 1442 1548 1774 0 7980 0 0 1593 2832 
65 52.65 885.4 6674 4545 2718 0 45.5 105.7 1878 2626 623 7.55 0 4100 3299 98.15 173.7 19728 34632 7755 13533 633 7777 0 30.2 709.7 196.3 2397 3426
5670 
10.07 425.3 3299 2580 2645 1250 2926 5148 2336
Average 
s.d. 21.18 604.3 3035 2201 5837 2975 7414 13007 5854 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 0 0 014028 0 0 2558 5727 603 0 0 0 286.9 0 0 47.82 117.1 65 0 0 4145 2250 0 0 1066 1757 613 0 75.5 3835 0 0 0 651.8 1560 
85 0 52.85 25021 173.7 0 0 4208 10196 623 0 0 16738 302 0 0 2840 6610 633 0 717.3 44553 50419 317.1 75.5 16014 24450 
Average 0 120.8 13470 9637 45.3 10.79 3881 
s.d. 0 264.8 16598 18682 119.9 28.54 11082 
Lavaca Bay 
Table 5. 5 (Cont.) Mollusc biomass 	jig vet vt/nTZ 
25 
3-10 cm 
year 1  Nov-84 Jan-85  Mar-85 Apr-85 May-85  Jun-85  Jul-85 Aug-85  Average  s.d.  
45  0  0  0  0  0  0  0  0  0  0  
603  0  0  0  0  0  0  0  0  0  0  
65  0  0  362.4  7218  0  0  0  15.1  949.4  2708  
613  0  558.7  16029  3413  1865  0  0  0  2733  5832  
85  0  0  0  5051  0  28048  0  0  4137  10454  
623  0  649.5  17116  0  9007  0  0  0  3347  6734  
635  20525  9770  46697  19102  0  0  15982  17444  

0 201.3 7690 3636 8224 6756 0 2.157 3430
Average 
s.d. 	0 313.2 9567 3919 17281 11790 0 5.707 8611 
s.d. 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 	Average 
45000000 00 603000000 00 65 0 52.85 2522 69241 75039 14481 26889 35505 613 0 0 9807 33779 76527 0 20019 30624 
85 0 0 11552 88690 19064 0 19884 34615 623 0 0 6236 6055 0 0 2049 3174 633 0 0 14677 39588 211.4 0 9046 15974 
Average 	0 7.55 6399 33879 24406 2069 11127 
23551
s.d. 	0 19.98 5826 35011 35780 5473 
10-20 cm year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average 
s.d. 
4500000000 00 60300000 000 00 
65 0 0 
0 634.2 0 0 0 7.55 80.22 239.2 613 0 0 6093 0 017803 0 0 2987 6739 
85 0 0 0 0 23903 70581 0 0 11786 26630 623 
0 0 	0 0 29785 0 0 2E+05 30840 80882 0 0 0 0 0 27376 4563 11176633 
Average 	0 0 870.4 90.6 7670 12598 0 34903 7276 
s.d. 	0 0 2303 239.7 13208 26330 0 80914 31238 
s.d. 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 	Average 
45000000 00 603000 000 
00 
65 0 158.6 0 22318 0 17101 6596 10291 613 0 0 0 99109 2E+05 49517
27165 	70754 
45787 66035 623 0:0 0IE+05 0 0 
85 0 0 0 30676 79237 2E+05 
21598 52904 
633 0 0 0 1721 0 0 	286.9 702.8 
Average 	0 22.65 0 40487 35723 29868 17684 
43778
s.d. 	0 59.93 0 52572 66492 60481 
Lavaca Bay 
-
Table 5.6. Benthic biomass mollusc biomass jig vet vt/m~2 
Totals 
year  1  Nov-84 Jan-65  Mar-85 Apr-85 May-85  Jun-85 Jul-85 Aug-85  Average  s.d.  
‘  
45  6349  10601  1925  2915  7717  3413  3020  687  4578  3522  
603  5373  3277  -2545  6946  1133  1488  816  506  2761  2236  
65  14783  3549  10532  17501  3656  3527  4402  2779  7591  5494  
’  
613  348  362.3  6710  943.2  1759  2128  2454  3095  2225  2072  
85  3201  7740  6818  2379  4213  8925  4907  1464  4956  2766  
623  3134  17162  34331  33386  7850  9777  8494  12117  15779  11539  
633  0  0  8826  17795  2084  770.3  8275  6721  5559  6200  

Average 4741 6099 10241 11695 4056 4290 4624 3910 6207 
s.d. 5009 6190 11068 11856 2755 3602 2893 4186 6994 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 2024 9017 23730 12035 3587 1986 8730 8401 603 1035 959 1948 3851 2159 747 1785 1163 
65 2250 33023 6282 13563 6298 2718 10656 11657 613 763 1503 5262 8614 6531 2514 4198 5098 85 1314 1004 9664 9241 6380 5867 5578 3740 
623 14068 20506 16738 9710 13643 6200 13478 5051 633 816 15765 11325 5216 22968 814.5 9484 8867 
Average 3181 11682 10707 8862 8795 2978 7701 
s.d. 4835 12177 7454 3407 7219 2223 7435 
-
0 3cm 
year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 
45 1306 2514 1895 2069 1601 3224 1155 498 1783 889.9 603 1344 2205 1110 6463 944 1050 619 317 1757 2132 65 438 2296 3578 1805 1737 2492 5352 830.7 2066 957.3 613 8 196 6581 233.8 491 837.7 1510 664 1315 2283 
65 1285 6811 3420 1601 1117 2469 686.7 566.3 2244 2201 623 2567 4047 13107 2771 2545 392.4 1510 966.2 3488 4359 633 6262 914 1963 253.8 8275 264.7 2989 3440 
Average 1158 3011 5139 2265 1485 1528 2444 586.7 2207 
s.d. 883.1 2229 4063 2022 688.6 1180 2728 256.3 2398 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 355 644 2922 3518 657 1102 1533 1342 603 589 642 1608 2069 287 619 969 701.1 65 1019 1389 3798 4394 2711 1450 2460 1403 613 559 1359 2620 1993 642 196 1228 937.5 
85 385 800.2 1842 4235 914 619 1466 1445 623 2977 8396 10737 2099 1155 914 4380 4150 633 544 3436 9905 4100 1382 573.5 3323 3550 
Average 918.3 2381 4776 3201 1107 781.9 
2194 
2431
s.d. 933.4 2824 3863 1107 793.6 409.5 
Lavaca Bag 
Table 5. 6, (Contfjenthic biomass mollusc biomass jig vet vt/nTZ
-
27 
3-10 cm 
year 1  Nov-84 Jan-65  Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85  Average  s.d.  
'  
45  4590  914  30  793  6116  189  581  189  1675  2167  
603  4021  1072 -1435  453  189  166  189  189  964.3  516.4  
65  14322  951  6667  9875  1896  1012  1050  724.9  4562  3625  
613  340  166.3  128.4  709.4  581.2  1253  649  2242  756.7 •  731.9  
85  1465  838  3398  589.1  3050  3889  4062  196  2186  1678  
623  559  4183  13650  446  4870  4115  6946  10230  5625  4386  
633  2544  14055  121.3  536.5  0  4916  3692  5406  

Average 4216 1354 3979 3843 2403 1594 1925 2670 2747 
s.d. 5259 1422 4831 5672 2380 1694 2604 3755 3677 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 
45 1669 2778 2356 2741 1865 378 1965 898 603 446 272 340 1782 1835 68 790.5 793.3 65 1231 1691 2484 8554 1918 1268 2858 2829 615 189 144 2643 6281 3956 748 2327 2458 85 929 151 7822 3873 4847 4825 3741 2824 
623 10676 1872 6002 6040 11982 4908 6913 3765 633 272 68 1420 746.6 21526 241 4046 8577 
Average 2202 996.6 3295 4288 6847 1777 3234 
s.d. 3775 1099 2647 2788 7398 2147 4114 
10-20 cm 1 Nov-84 Jan-85 s.d.
year Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average 45 453 7173 0 53 0 0 1284 0 1120 2670 603 8 0 030 0272 8 0 39.75101 65 23 302 287 5821 23 25 0 1224 962.8 2126 613 0 0 0.15 0 687.2 37.1 295 189 151.1 254.2 65 455 91 0 189 45.7 2567 158 702 525.7 925.7 623 8 8932 7573 30169 415.3 5270 38 920.8 6666 10567 653 0 2846 0 0 0 1541 731.1 1206 
Average 157.5 2750 1123 5587 167.3 1167 254.7 653.7 1484 
3.d. 229 4147 2846 11058 274.3 2037 466.9 613.2 4482 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 0 5595 18452 5776 1065 506 5232 6961 
•
603 0 45 0 0 37 60 23.67 26.96 65 0 29942 0 415.2 1669 0 5338 12071 613 15 0 0 340.1 1933 1570 643 675.9 85 0 53 0 1132 618.8 423 371.2 451.7 623 415 10238 0 1571 506 378 2185 3980 633 0 12261 0 369.6 60 0 2115 4973 
Average 61.43 8305 2636 1372 841.2 419.6 2273 
s.d. 156 10803 6974 2015 746.7 549.9 5750 
Lavaca Bay Table 5.7, Chironomidlarvae Individuals/m~2 Totals year 1 Nov-64 Jan-65 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 45 151 5965 3171 3598 850.5 8909 3775 2341 603 75.5 528.5 377.5 2945 981.5 1812 604 755 65 226.5 226.5 1208 830.5 679.5 1888 679.5 679.5 613 0 75.5 604 0 226.5 1559 906 226.5 85 0 0 0 151 151 0 0 0 623 0 75.5 75.5 2039 75.5 75.5 0 0 633 0 0 0 528.5 75.5 302 75.5 0  Average s.d. 3567 2641 1010 924.1 802.2 528 424.7 498.6 37.75 73.68 292.6 752.5 122.7 201.8  28  
Average s.d.  64.71 91.73  981.5 2205  776.6 1141  1413 1578  451.4 386.7  2049 5130  862.9 1335  571.6 844  893.9  1604  
year 2 45 603 65 613 85 623 hvO  Oct-85 0 0 0 0 0 0 0  Dec-85 75.5 0 0 75.5 0 0 0  Feb-86 Apr-86 4757 377.5 0 151 850.5 151 151 151 0 0 0 151 0 0  Jun-86 Auq-86 0 4002 0 151 0 75.5 151 0 0 0 151 0 75.5 0  Average s.d. 1535 2220 50.53 77.98 176.2 326.2 88.08 74.25 0 0 50. jj yj no « «.?O 12.58 50.82  
Average * A v'.U.  0 0  21.57 C'u.84  01Q 7 IJ 1 -J. 1 1762  140.2 126.6  53.95 71.81  604 1499  273.2  944  
0 — 3 crn year 1 45 603 65 613 85 625 c>co  Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 151 5889 5096 5171 831 8909 3096 1888 76 529 302 2567 906 1812 453 529 227 227 906 755 529 1888 680 453 0 76 604 0 227 906 529 76 0 0 0 151 151 0 0 0 n 76 76 1965 76 76 0 0 0 453 76 502 76 0  Average s.d. 5579 2718 896.6 851.8 707.8 536.9 302 340 37.75 73.68 r-o~ i 723.8 151 184.9  
Average s.d.  75.5 95.5  1133 2338  711.9 1104  1294 1265  399.1 556  1985 3151  690.3 1095  420.6 684.9  847.3  1579  
year 2 45 605 65 613 85 623 635  Oct-85 0 0 0 0 0 0 0  Dec-85 Feb-86 Apr-86 Jun-86 Auq-86 76 2190 378 0 3926 0 0 151 0 151 0 604 151 0 76 76 151 151 76 0 0 0 0 0 0 0 0 151 151 0 0 0 0 76 0  - Average s.d. 1095 1623 50.55 77.98 138.4 236 75.5 67.53 0 0 50.55 77.98 12.58 30.82  
Average s.d.  0 0  21.57 36.84  420.6 810.7  140.2 126.6  43.14 59.4  593.2 1471  203.1  683.8  

Lavaca Bay 
Table 5.7 (Cont) Chironomid larvae lndividuals/m~2 
3-10 cm 
year 1  Nov--84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aog-85  Average  s.d.  
45  0  76  76  -76  0  0  680  453  169.9  264.6  
603  0  0  76  378  0  0  151  227  103.8  143.6  
65  0  0  151  76  151  0  0  0  47.19  •  71.81  
613  0  0  0  0  0  455  302  151  1 13.3  183.5  
85  0  0  0  0  0  0  0  0  0  0  
625  0  0  0  76  0  0  0  0  9.438  28.54  
655  0  76  0  0  0  0  12.58  30.82  

Average 0 12.58 45.14 97.07 21.57 64.71 161.8 118.6 67.1 1 
s.d. 0 30.82 59.4 128.7 57.07 171.2 255.8 173.6 140.4 
gear2 Oct--85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 0 02567 0 0 76 440.41042 
603000 'o00 00 65 0 0 227 0 0 0 37.7592.47 613 0 0 0 0 76 0 12.5850.82 85000000 00 
623000000 00 633000000 00 
Average 0 0 399.1 0 10.79 10.79 70.11 
s.d. 0 0 959.7 0 28.54 28.54 396.5 
10-20 
cm 
uear 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average S.d. 
45 0 0 0151 0 0 0 0 18.8857.07 603 0 0 0 076 0 0 0 9.43828.54 65 0 0 151 0 0 0 0227 47.1994.64 613000000760 ATO28.54
<j
r.nju 
or00000000 00
UJ 
62300000000 00 6o3 000000 00 
: 
Average 0 0 21.57 21:57 10.79 0 10.79 32.36 12.58 , s.d. 0 0 57.07 57.07 28.54 0 28.54 85.61 43.38 
year 2 Oct-85 Dec-65 Feb-86 Apr-86 Jun-86 Aug-66 Average s.d. 
45000000 00 603000000 0 .0 65000000 00 613000 ?000 00 85000 io00 00 6230000 00 00 
653000000 00 
Average 000000 0 
s.d. 000000 
Lavaca Bag 
Table 5.7.  Stroblospio benedicti  Individuals /  m~2  
Totals  
year 1  Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85  Jul-85 Aog-85  Average  s.d.  
45  227  982  0  378  0  0  76  0  207.6  369.1  
603  4153  1510  2341  1888  1284  1208  151  0  1567  858  
65  76  76  76  227  227  1133  4002  1737  943.8  .  1440  
613  22?  76  0  227  680  1208  3624  1888  990.9  1304  
85  1661  2794  1133  906  1359  2643  2869  1208  1821  877.1  
623  4153  3096  4228  755  2492  1435  1359  1963  2435  1186  
6oo  1965  529  151  0  529  1737  817.9  829  

Average 1749 1422 1391 701 884 1089 1801 1219 1271 
s.d. 1949 1305 1578 583 891 907 1674 867 1249 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 
45 453 76 76 755 1153 0 415.3 454.9 603 1057 2945 2869 5512 2039 378 2466 1800 65 5247 151 455 6795 5134 982 2794 2736 613 1888 1586 5965 5775 2265 1284 2794 1781 
85 831 76 755 1965 529 906 843.1 625.2 
6'2vj 2541 4908 5210 3096 4606 2945 3851 1200 633 227 1359 3020 2945 2190 1208 1825 1092 
Average 1435 1586 2621 3549 2556 1100 2141 
s.d. 1098 1805 2357 2055 1706 934 1831 
-
0 3cm 
year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 45 227 982 0 378 0 0 76 0 207.6 369.1 603 3926 1435 2341 1888 1284 1208 76 0 1519 869.5 65 76 76 0 227 227 1133 5624 1661 877.7 1316 613 227 76 0 227 680 1133 3247 1586 896.6 1152 
85 1359 2645 1155 906 1559 2643 2869 906 1727 894.2 625 4077 2492 4002 755 2492 1359 1559 1888 2503 1069 633 1888 529 151 0 529 1737 805.3 808.5 
Average 1648 1284 1337 701 884 1063 1683 1111 1205 
s.d. 1881 1126 1517 583 891 901 1540 820 1177 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 
45 453 76 0 755 1057 0 590.1 445.9 603 604 2567 2718 5361 1359 378 2164 1842 65 2945 151 378 6116 5134 906 2605 2558 
613 1661 1586 5814 3549 2265 1133 2668 1754 
85 755 76 755 1812 529 906 805.3 572.3 623 1965 4908 5210 3096 3926 2190 3549 1365 633 227 1359 3020 2945 2114 1133 1799 1097 
Average 1230 1532 2556 3376 2341 949 1997 
s.d. 991 1763 2324 1873 1647 688 1758 
Lavaca Bay Table 5.7 (Cont.) Streblospio bencdicti Individuals / m‘2 
' 
3-!0 cm 
year t  Nov-84 Janes  Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85  s.d.Average  
45  0  0  0  0  0  0  0  0  0  0  
603  151  0  0  0  0  0  76  0  28.31  28.54  
65  0  0  76  0  0  0  378  76  66.06  137.8  
613  0  0  0  0  0  76  378  302  94.38  162:3  
85  302  151  0  0  0  0  0  302  94.38  118.8  
623  76  604  227  0  0  76  0  76  132.1  219.8  
653 b  76  0  0  0  0  0  12.58  30.82  

Average 88 126 54 0 0 22 119 108 62.92 
s.d. 121 242 84 0 0 37 179 137 126.8 
Oct-85 Dec-85 Average s.d. 
•
year 2 Feb-86 Apr-86 Jun-86 Aug-86 45 0 0 76 0 76 0 25.1738.99 603 453 378 151 151 680 0 302 248.1 65 302 0 76 680 0 76 188.8 264.8 613 227 0 151 227 0 151 125.8 103.2 
63.17
8576 0 0151 0 0 37.75 
623 378 0 0 0 604 755 289.4 339.1 635 0 0 0 0 76 76 25.1738.99 
Average 205 54 65 173 205 151 142 
s.d. 183 143 68 242 301 272 212.4 
10-20cm year 1 Nov-84 Janes Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average 
s.d. 
0
4500000000 0 
60376 76 0 0 0 0 0 0 18.8828.54 6500000000 00 61300000000 00 8500000000 00 62300000000 00 633 000000 00 
Average 1313 0 0 0 0 0 0 2.796 
s.d. 3131000000 14.39 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 
45000000 00 603000000 00 65000000 00 61300000 -0 00 85000000 00 623 0 0 0 0 76 0 12.5830.82 633000000 00 
Average 0 0 00 11 0 1.798 
s.d. 0 0 0 0 29:0 11.65 
Lavaca Bay 
Table 5.8. 
hctHvmwtls cvllfvrtfHicnsls lwHvlrttial9/M‘2 
Totals 
year  1  Nov-84 Jan-85 Mar-85 Apr-85 May-85  Jun-85 Jul-85 Aug-85  Average  s.d.  
45  76  76  0  76  378  0  0  0  75.5  137.8  
603  604  0  0  0  76  76  76  0  103.8  40.36  
65  2341  1965  2794  2794  2643  2567  1359  1435  2237  630  
613  0  680  151  529  378  453  76  151  302  225.9  
85  6267  4077  5587  407?  5210  5851  4153  3700  4615  721.5  
623  680  3096  4550  2039  5059  4077  3775  4530  3473  1024  
653  1135  680  227  982  0  76  515.9  485.2  

Average 1661 1648 2028 1456 1995 1715 1348 1413 1658 
s.d. 2409 1686 2312 1554 2316 1762 1854 1929 1877 
year 2 Oct-65 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 151 151 151 755 453 0 276.8 277.1 603 0 0 76 529 302 0 151 218.8 
65 680 4757 6644 4379 6191 604 3876 2645 615 982 227 1812 1963 1586 906 1246 659.5 
85 2265 1812 755 9287 5814 4379 4052 3152 625 2265 3171 7852 4832 3775 3096 4165 1997 655 151 2567 7097 8532 6267 831 4241 3517 
928 1812 3484 4325 3484 1402 2572
Average 
s.d. 975 1809 3538 3543 2693 1677 2713 
-
0 3cm 
1 45 76 76 0 0378 0 0 0 66.06140.8 605 529 0 0 0 76 0 76 0 84.9436.64 65 2039 1057 2190 2643 2492 2416 680 378 1737 954.9 
615 0453 151 151 0 0 0 0 94.38168 85 2945 2718 4530 2567 1057 1284 1057 1208 2171 1299 625 302 755 2265 680 1586 76 680 151 811.6 784.3 
655 529 453 227 453 0 76 289.4 221 
gear Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 
Average 982 845 1581 928 831 604 356 259 767.6 
s.d. 1218 1002 1703 1172 932 926 440 440 1038 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. -45 151 151 151 680 455 0 «• 264.3 251.5 605 0 0 0 378 151 0 88.08 154.1 65 0 5020 4228 378 4757 76 2076 2187 615 982 151 378 227 0 0 289.4 368.1 
. 
85 1208 1510 151 4606 1661 302 1573 1611 625 76 2492 5965 604 302 302 1623 2303 635 151 2567 5059 7550 2416 529 3045 2817 
Average 367 1413 2276 2060 1391 173 1280 
s.d. 505 1308 2676 2877 1731 208 
1903 
_ 
Lavaca Bag 
Mediomastia califoronienals individuala/m~2
Table 5.8 (Cent.) 

3-10  cm  J  
year 1  Nov-84 Jan-85  Mar-85 Apr-85 May-85  Jun-85 Jul-85 Aug-85  Average  s.d.  
45  0  0  0  76  0  0  0  0  9.438  28.54  
603  0  0  0  0  0  76  0  0  9.438  28.54  
65  302  906  378  151  151  151  604  1057  462.4  379.7  
613  0  227  0  378  302  453  76  151  198.2  163.1  
85  3020  1559  982  1510  4077  2492  2718  2190  2293  1044  
623  378  2190  2265  1284  3247  3700  3096  3926  2510  941.7  
653  604  227  0  529  0  0  226.5  278.4  

Average 617 780 604 518 1111 1057 928 1046 837.5 
s.d. 1189 879 821 616 1762 1448 1373 1510 1198 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Auq-86 Average s.d. 45 0 0 076 0 0 12.5830.82 603 0 0 76 151 151 0 62.92 74.23 65 680 1661 2416 3851 1435 529 1762 1235 613 0 76 1435 1661 906 378 742.4 704.1 
65 1057 302 604 4681 4077 3700 2403 1956 623 2190 680 1688 4228 3398 2492 2479 1251 633 0 0 2059 906 3851 502 1183 1517 
Average 561 TOO 1208 2222 1974 1057 1235
JUU 
s.d. 834 614 981 1986 1762 1448 1449 
10-20 cm year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 4500000000 00 
605760000 000 9.4580 65 0 0227 0 0 0 76 0 37.7585.61 613 0 0 0 076 0 0 0 9.43828.54 
85 502 0 76 0 76 76 378 502 151 149.2 625 0 151 0 76 227 302 0 455 151 167.2 633 000000 00 
Average 63 25 43 11 54 54 65 108 53.13 
s.d. 121 62 86 29 84 113 141 189 109.4 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45000000 00 
*
603000000 00 65 0 76 0 151 0 0 37.7563.17 
613 0 0 0 76 680 529 213.9 307.3 
85 0 0 0 0 76378 75.5151 623 0 0 0 0 76302 62.92 121 633 0 0 0 76 0 0 12.5830.82 
. 
Average 0 11 0 43 119 173 57.52 
s.d. 0 29 0 59 250 225 147.1 
Lavaca Bay 
Individuals/nTZ
Table 5.9, Hobsonia florida 
3-10 cm gear 1 45 603 65 613 85 623 635  Nov-84 Jan-85 Mar-85 Apr-85 May -85 Jun-85 0 0 0 ,0 0 0 0 0 0 0 0 0 0 0 0 0 76 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 76 0 151 76 0 0 0 0  Jul-85 Aug-85 453 0 0 0 0 0 0 0 0 0 0 0 0 0  Average s.d. 56.63 171.2 0 0 9.438 . 28.54 0 0 0 0 37.75 59.4 0 0  
Average s.d.  0 0  0 0  11 29  0 0  32 59  11 29  65 171  0 0  15.38  66.21  
gear 2 AC -tJ 603 65 615 85 623 633  Oct-85 Dec--85 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Feb-86 Apr-86 0 0 0 76 0 0 0 0 0 0 76 0 0 0  Jun-86 Aug-86 0; 0 0! 0 0 0 o 0 0 0 0 0 0 0  Average s.d. 0 0 12.58 30.82 0 0 0 0 0 0 12.58 30.82 0 0  
Average s.d.  0 0  0 0  11 29  11 29  0 0  0 0  3.595  16.27  
10-20 cm year 1 Nov-84 45 0 603 0 65 0 613 0 85 0 623 0 635  Jan-85 Mar-85 Apr-85 May -85 Jun-85 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Jul-85 Aug-85 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Average s.d. 0 0 0 0 0 0 0  0 0 0 0 0 0 0  
Average s.d.  0 0  0 0  0 0  0 0  0 0  0 0  0 0  0 0  0  0  
year 2 45 603 65 613 85 623 633  Oct-85 Dec--85 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Feb-86 Apr-86 0 0 0 0 0 0 0 0 0 0 0 : 0 0 0  Jun-86 Aug-86 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Average 0 0 0 0 0 0 0  s.d.  0 0 0 0 0 0 0  

000000
Average 0 
0
s.d. 000000 
. 
Lavaca Bay 
Table 5.9 (Cent.) Hobmi*florid* (ndividutlt/m‘2 Totals 

year  1  Nov-84  Jan-85 Mar-85 Apr-85 May-85  Jun-85 Jul-85 Aug-85  Average  s.d.  
45  0  680  0  604  0  529  1057  0  358.6  417.8  
603  0  0  0  529  76  0  0  0  75.5  197  
65  0  0  0  227  227  2114  76  76  339.8  766.8  
613  0  151  0  76  0  151  0  0  47.19  71.81  
85  0  0  0  76  578  502  0  0  94.38  162.3  
623  0  76  227  906  1153  227  0  0  320.9  460.1  
653  151  151  151  76  0  0  88.08  74.25  

Average 0 151 54 367 280 485 162 11 192.9 
s.d. 0 266 95 319 399 738 396 29 380.1 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Auq-86 Average s.d. 45767676604 0 0 
138.4 251.1 
603 0 0 0 76 0 0 12.5830.82 65 0 0 076 0 0 12.5850.82 613000000 00 85000000 00 
623 0 0 302 0 0 0 50.33123.3 633000000 00 
0 0 30.56
Average 11 11 54 108 
s.d. 29 29 113 222 0 0 104.2 
-
0 3cm 
year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 
45 0 680 0 604 0 529 604 0 302325.8 605 0 0 052976 0 0 0 75.5197 65 0 0 0 227 151 2114 76 76 oc*0.o 770 
0 76 0 151 0 0 47.19 71.81 
85 0 0 0 76 378 302 0 0 94.38162.5 623 0 76 151 906 982 151 0 0 283.1 428.7 635 151 151 151 76 0 0 83.08 74.23 
613 0 151 
Averaqe 0 151 43 367 248 475 97 11 177.6 
s.d. 0 266 74 319 348 743 225 29 358.4 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 76 76 76 604 0 0 158.4 231.1 603000000 00 65 0 0 076 0 0 12.5850.82 613000000 00 
085000000 0 
623 0 0 227 0 0 0 37.7592.47 633000000 00 
Average 11 11 43 97 0 0 26.96 
'
s.d. 29 29 86225 0 0 99.8 
Lavaca Bay 
Table 5.10. L«*onerei«culveri lndividualg/m~2 Totals 

year  1  Nov-84 Jan-65  Mar-85 Apr-85 May-85  Jun-85  Jul-85 Aug-85  Average  s.d.  
45  76  151  0  0  76  76  0  0  47.19  59.4  
603  76  0  0  0  0  0  0  0  9.438  0  
65  0  0  76  76  0  0  0  76  28.31  •40.36  
613  76  0  0  0  0  0  0  0  9.438  0  
85  76  0  0  0  0  0  0  76  18.88  28.54  
623  0  151  76  227  0  0  680  453  198.2  2542  
635  *  0  0  227  0  76  378  115.5  156.6  

Average 50 50 22 43 43 11 108 140 58.72 
s.d. 39 78 37 86 86 29 254 192 125.9 
year 2 (Jet-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45 76 151 227 1737 302 151 440.4 639.6 
603:000000 00 6576 0 0578 0 0 75.5151 613 0 0 76 0 227 0 50.55 91.44 
85 0 076 0 0 0 12.5830.82 625 453 151 0 0 151 151 151 165.4 6o3 76 227 0 0 0 0 50.33 91.44 
Average 97 76 54 o02 97 43 111.5 
s.d. 161 97 84 648 129 74 280.6 
-
0 3cm 
year 1 Nov-84 Jan-65 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 4576 76 0 0 0 0 0 0 18.8826.54 60300000000 00 6500000000 00 61300000000 00 85000000076 9.45828.54 623 0 0 76 0 0 0 302 302 84.94142.7 633 0 0 227 0 76 227 88.08 111.1 
Average 13 13 11 0 32 0 54 86 26.56 
s.d. 31 51 29 0 86 0 113 127 72.09 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 
•
45 76 0 151 1510 151 0 514.6 589.5 603000000 00 65 76 0 0 227 0 0 50.3391.44 613000000 00 
85000000 00 623 76 76 0 0 76 0 37.75 41.35 633 76 151 0 0 0 0 37.75 63.17 
Average 43 32 22 248 32 0 62.92 
s.d. 40 59 57 563 59 0 235.2 
Lavaca Bay 
Laconcrcis culvcri Individuals/in^Z
Table 5.10 (Cent.) 
3-! Ocm 
year 1  Nov-84 Jan--85 Mar--85 Apr-85 May -85 Jun-85 Jul-85 Aug-85  Average  s.d.  
45  0  0  0  0  76  76  0  0  18.88  36.84  
603  76  0  0  0  0  0  0  0  9.438  0  
65  0  0  76  76  0  0  0  76  28.31  40.36  
613  76  0  0  0  0  0  0  0  9.438  0  
85  0  0  0  0  0  0  0  0  0  0  
623  0  76  0  151  0  0  378  76  84.94  135.9  
633  0  0  0  0  0  76  12.58  30.82  
Averaqe 25 13 11 32 11 11 54 32 23.77 


s.d. 39 31 29 59 29 29 143 40 60.16 
s^.
year2 Oct-85 Dec--85 Feb-•86 Apr-86 Jun-86 Aug-86 Average 45 0 76 0 151 76 76 62.92 56.85 603000000 00 65 0 0 0 151 0 0 25.1761.65 613 0 0 76 0 0 0 12.5830.82 85 0 076 0 0 0 12.5830.82 625 302 0 0 0 0 151 75.5 126.3 
633000000 00 
Averaqe 43 11 22 43 11 32 26.96 
s.d. 114 29 37 74 29 59 61.99 
10-20 cm 
year 1 Nov-84 Jan--85 Mar-•85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 

45076000000 9.43828.54 60300000000 00 6500000000 00 61300000000 00 
85760000000 9.4580 623 076 076 0 0 076 28.3140.36 633 0 0 0 0 0 76 12.5830.82 
Average 1325 0 11 0 0 022 8.389 
s.d. 31 39 029 0 0 037 23.95 
year2 Oct-85 Dec-¦85 Feb-86Apr-86 Jun-86 Aug-86 Average s.d. 
45 0 76 76 76 76 76 62.92 30.82 6030000 00 00 65000000 00 613 0 0 0 0 227 0 37.7592.47 85000000 00 623 76 76 0 0 76 0 37.75 41.35 633 0 76 0 0 0 0 12.5830.62 
Average It 32 11 11 54 It 21 57 
s.d. 29 40 29 29 84 29 45.01 
Lavaca Bay 
Table 5.11. Mulinia lateralis Individuals/m ~2 Totals year 1 Nov -84 Jan-85 Mar-85 Apr-85 May -85 Jun-85 Jul-85 Aug-85 45 0 0 0 o 0 0 0 0 603 0 0 0 0 0 0 0 0 65 0 76 76 151 227 0 0 76 613 0 0 76 0 0 0 0 0 85 0 227 151 378 227 302 0 0 625 0 0 227 0 151 0 76 0 635 151 0 0 76 76 0  Average s.d. 0 0 0 0 75.5 • 80.71 9.438 28.54 160.4 143.6 56.63 91.73 50.35 61.65  38  
Average s.d.  0 0  50 91  97 84  76 145  86 111  54 113  22 37  11 29  50.33  90.41  
year 2 45 603 65 613 85 62o> 633  Oct--85 0 0 0 0 0 0 76  Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 0 0 578 0 ! 0 0 0 0 0 0 76 151 455 0 0 0 453 0 0 0 76 1284 151 0 0 0 151 76 0 0 227 1359 1208 0 0  Average s.d. 62.92 154.1 0 0 115.3 177.1 75.5 184.9 251.7 509.1 37.75 63.17 478.2 651.1  
Average s.d.  11 29  54 84  485 591  524 429  0 0  0 0  145.6  340.7  
0 -3 cm year 1 45 603 65 613 85 623 635  Nov--84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 0 0 0 0 0 0 0 0 0 0 0 0 0 76 76 76 227 0 0 0 76 0 0 0 0 227 151 578 76 502 0 0 227 0 151 0 151 0 0 76  Jul -85 Aug-85 0 0 0 0 0 76 0 0 0 0 76 0 76 0  Average s.d. 0 0 0 0 66.06 75.5 9.438 28.54 141.6 147.4 56.63 91.75 50.33 61.65  
Average s.d.  0 0  50 91  97 84  65 141  65 92  54 113  22 37  11 29  46.14  86.04  
year 2 45 603 65 613 85 623 633  Oct--85 0 0 0 0 0 0 76  Dec-85 Feb-86 Apr-86 0 0 578 0 0 0 0 151 453 0 453 0 76 1284 151 0 151 76 227 1359 1208  Jun-86 Aug-86 0 0 0 0 0 0 0 0 0 0 0 0 0 0  ¦­ Average s.d. 62.92 154.1 0 0 100.7 182.9 75.5 184.9 251.7 509.1 37.75 63.17 478.2 631.1  
Average s.d.  11 29  43 86  485 591  324 429  0 0  0 0  143.8  341.3  

Lavaca Bag Table 5.11 (Cent) Malinia htcralij Individaals/m *2 
3-10cm year 1 45 603 65 613 85 623 633  Nov-84 Jan-85 Mar-85 Apr-85 May -85 Jun-85 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 76 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Jul-85 0 0 0 0 0 0 0  Aug-85 0 0 0 0 0 0 0  Average s.d. 0 0 0 0 9.438 28.54 0 0 0 0 0 0 0 0  
Average s.d.  0 0  0 0  0 0  11 29  0 0  0 0  0 0  0 0  1.398  10.27  
year 2 45 603 65 613 85 623 633  Oct-85 Dec--85 Feb-86 Apr-86 Jun -86 Auq-86 0 0 0 0 0 0 0 0 0 0 0 0 0 76 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Average s.d. 0 0 0 0 12.58 30.82 0 0 0 0 0 0 0 0  
Average s.d.  0 0  11 29  0 0  0 0  0 0  0 0  1.798  11.65  
10-20 cm year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 45 0 0 0 0 0 0 603 0 0 0 0 0 0 65 0 0 0 0 0 0 613 0 0 0 0 0 0 85 0 0 0 0 151 0 623 0 0 0 0 0 0 633 0 0 0 0  Jul-85 0 0 0 0 0 0 0  Aug-85 0 0 0 0 0 0 0  Average s.d. 0 0 0 0 0 0 0 0 18.88 57.07 0 0 0 0  
Average s.d.  0 0  •  0 0  0 0  0 0  22 57  0 0  0 0  0 0  2.796  20.55  
year 2 45 603 65 613 85 623 633  Oct-85 0 0 0 0 0 0 0  Dec--85 Feb-86 Apr-86 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Jun-86 Aug-86 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Average s.d. 0 0 0 0 0 0 0  0 0 0 0 0 0 0  
Average s.d.  0 0  0 0  0 0  0 0  0 0  0 :o  0  0  

Lavaca Bay 
Table 5.12  tiacoma mitchilli  Individuals/m "2  40  
Totals  
gear 1  Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85  Jul-85 Aug-85  Average  s.d.  
'  
45  0  0  0  .0  0  0  0  0  0  0  
603  0  0  0  0  0  0  0  0  0  0  
65  0  76  151  151  0  0  0  0  47.19  ,71.81  
613  0  529  1435  378  76  151  0  0  320.9  511  
85  453  982  453  378  76  227  151  227  368.1  504.2  
623  76  76  680  151  302  0  76  0  169.9  242:1  
635  755  151  76  76  0  76  188.8  281.5  

88 277 496 173 76 65 32 43 155.2
Average 
s.d. 181 399 515 155 107 92 59 86 278.4 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45000000 00 605000000 00 
65 0 0 1757 831 378 76 505.5 683.1 
613 0 76 1737 1455 982 76 717.3 769.6 85 0 76 2265 906 227 0 578.8 894.2 623 0 0 1057 529 0 0 264.3 442.2 
633 0 604 2794 529 151 76 692.1 1059 
Average 0 108 1370 604 248 o2 393.7 
s.d. 0 222 1076 512 353 40 685.6 
-
0 3cm 
year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average s.d. 4500000000 00 60300000000 00 
o oo
650760760000 i36.84
1u.uu 
613 0 455906227 0 0 0 0 198.2346 
85 453 982 453 502 0 0 151 227 520.9 340.4 625 76 0 151 151 0 0 76 0 56.65 71.81 633 151 76 0 0 0 0 37.75 65.17 
Average 88 252 237 119 0 0 32 32 92.28 
s.d. 161 399 336 114 0 0 59 86 206.2 
year 2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average s.d. 45000 000 00 603000000 00 65 0 01284 0 0 0 213.9524 613 0 76302 0 0 0 62.92 121 
85 0 76 1812 0 0 0 314.6 734.2 623 0 0 906 0 0 0 :151369.9 633 0 604 2265 0 0 76 490.8 900.6 
Average 0 108 938 0 0 11 
176.2 
s.d. 0 222 895 0 0 29 495.1 
Lavaca Bay Macoma mitehilli Individaals/m ~2
Table 5.12 (Cent.) 

3-10  cm  *  
year  1  Nov-84 Jan-85 Mar-85 Apr-65 May-85 Jun-85 Jul -85 Aug-85  Average  s.d.  
45  0  0  0  0  0  0  0  0  0  0  
603  0  0  0  0  0  0  0  0  0  0  
65  0  0  151  0  0  0  0  0  16.88  57.07  
613  0  76  378  151  76  0  0  0  84.94  135.9  
85  0  0  0  76  0  76  0  0  18.88  36.84  
623  0  76  529  0  227  0  0  0  103.8  199.1  
653  604  76  76  76  0  0  138.4  231.1  

0 25237 43 54 22 0 0 48.94
Average 
s.d. 0 39263 59 84 37 0 0 122.8 
s.d. 
year2 Oct-85 Dec-85 Feb-86 Apr-86 Jun-86 Aug-86 Average 
45000000 00 603000000 0 
0 
65 0 0 453 680 378 76 264.3 281.5 613 0 0 1455 680 502 0 402.7 572.3 85 0 0453755 151 0 
226.5 313.1 
623 0 0 151 151 0 0 50.33 77.98 633 0 0 529 453 151 0 188.8 
242.3 
Average 0 0 431 588 140 11 161.8 
s.d. 0 0 495 335 154 29 299.5 
10-20 cm year 1 Nov-84 Jan-85 Mar-85 Apr-85 May-85 Jun-85 Jul-85 Aug-85 Average 
s.d. 
4500000000 00 60300000000 00 65000760000 9.43828.54 613 0 0 151 0 0 151 0 0 37.7573.68 
85 0 0 0 076151 0 0 28.3159.4 623 0 0 0 076 0 0 0 9.43828.54 633 0 0 0 0 0 76 12.5830.82 
0 022 112243 0 11 13.98
Average 
s.d. 0 057293774 029 39.01 
* 
year2 Oct-85 Dec-85 Feb-86Apr-86 Jun-86 Aug-86 Average s.d. 45000000 0 
0 
603000000 00 
65 0 0 0 151 0 0 25.1761.65 613 0 0 0 755 680 76 251.7 362.6 
. 
0 63.17
'85 0 0 0151 76 37.75 
623 0 0 0 378 0 0 62.92154.1 633 0 0 0 76 0 0 12.5830.82 
216 108 11 55.73
Average 0 0 0 
s.d. :o 0 0 270 254 29 164.3 
CHAPTER 6 
FINFISH AND SHELLFISH 

PURPOSE 

The purpose of this study was to provide data on the utilization of the 
Lavaca River delta estuarine zone as a nursery habitat by finfish and selected 
macro-invertebrates. The sampling design was such that both seasonal and 
spatial patterns could be investigated. 
METHODS 
Sampling sites and schedules are described in the Introduction. Finfish 
and macro-invertebrates (henceforth referred to as fish except when specific 
species are mentioned) were sampled with four types of collecting gear. 
Ichthyoplankton were sampled with a 0.5 m diameter conical net made of 
505 fim mesh and a filtering cod end. This net, fitted with a flowmeter to 
measure water volume filtered, was towed at the surface for three minutes. 
Duplicate samples were taken at each station. 
Postlarval and juvenile fish were collected along the shoreline with a 
benthic sled and a bag seine. The benthic sled was a 17.8 by 53.3 cm box on 
steel runners with a 1800 /xm mesh net attached to one end. This net was 
towed 30 m by hand and sampled an area of 12 The seine was 6.1 m long 
and 1.8 m high with a 1.8 x 1.8 m bag. The entire seine was made of 2 mm 
mesh nylon. This net was pulled along the shoreline for 15 m and sampled an 
area of approximately 47 Duplicate sled and seine samples were taken at 
each sampling site. 
Juvenile fish were collected in open water (i.e. away from shorelines) 
with a 3 m otter trawl of 1.9 cm stretched mesh in both the wings and cod 
end and in addition, the cod dnd was fitted with a liner of .64 cm delta mesh. 
This net was towed for 3 minutes at 1200 rpm. Tows were made down-stream 
at the river stations and with the wind at all other sites. Trawl samples 
were taken in triplicate. Ichthyoplankton and trawl samples, along with 
Sled
zooplankton samples, were taken at the same sites on the same day. and 
seine samples were taken at the same sites on the same day but on different 
days from the above mentioned samples. (Sled and seine samples were generally 
taken the following day.) 
All samples were preserved immediately in 5 percent seawater formalin (10 
percent for trawl samples) and returned to the laboratory for processing. In 
the lab, all individuals were counted and up to 50 individuals of each species 
were measured (standard length to 1 mm) and weighed (to the nearest 0.01 g). 
When more than 50 individuals of one species were present the total weight 
for all individuals was obtained. A voucher collection was established and all 
other material was discarded. 
The basic analytical tool used for these data was cluster analysis. 
Cluster analysis involves the computation of the dissimilarity coefficients 
between all possible pairs of entities (i.e., collections) based on the attributes 
(i.e., density of each species) of those entities. These coefficients are then 
sorted into clusters or groups with high inter-group similarity and the results 
are presented in the form of a tree diagram (dendrogram) (see Clifford and 
Stevenson 1975, Romberg 1984 for complete discussion of cluster analysis). 
The dissimilarity measure used here was the Canberra-Metric (Lance and 
Williams 1967 a cited by Clifford and Stevenson 1975) which is: 
n-Xjj Xik 
(1/n) E 
i=l 
(Xij = Xik) 

Where X is the abundance of the jth species at the and stations
jth 
and n the number of species.
= 
Since this coefficient is the mean of a series of fractions, an 
outstandingly large value will contribute to only one of the fractions, giving 
abundant and uncommon species equal influence. On the other hand, it is 
strongly influenced by presence/absence data. If Xjj is 0 and X2'} is any 
whole number the result is unity; therefore, differences of 0 and 1000 and of 0 
and 1 carry the same weight, which does not make good ecological sense. The 
solution to this is to replace the 0 values with a number which is 1/5 of the 
smallest recorded value and Stevenson 1975). In this case our
(Clifford 
smallest values are 1 so the 0 values were replaced by 0.20. We used the 
flexible sorting strategy with a 6 value of -0.25 (Lance and Williams 1967, 
Sneath and Sokol 1973). All computations were done on an IBM 3081 in the 
Computation Center at the University of Texas at Austin. 
Many similarity and dissimilarity measures and clustering strategies have 
been developed but only a few are commonly used in ecological research 
(Romberg 1984). The variety of dissimilarity measures is much greater than 
clustering strategies. Although we had chosen Canberra-metric a priori for 
these data, we examined them using three measures: Euclidian distance, Bray-
Curtis, and Canberra-metric. Canberra-metric gives equal weight to all 
species, a desirable property in the investigation, whereas the other two give 
considerable weighing to abundant species. The results from the three analysis 
in
were generally similar however, that temporal patterns predominated and 
were roughly similar among the analysis. Spatial patterns were minor to non­
existent in all analysis. This indicates to us that the temporal/spatial 
patterns 
presented here are .the true patterns in the data and are relatively unaffected 
by choice of analytical methods. 
Our approach was to put each time/site (i.e. Nov 1984 station 45 as one 
"time/site" and July 1985 station 603 as another) into the analysis 
simultaneously and cluster them based on the species composition and 
abundance at each of the 98 time/sites. The results of such an analysis could 
take two substantially different forms. First, if temporal patterns are the 
dominant feature in the fish community, then the clusters would separate time 
periods and spatial patterns would be manifested only within the time period. 
Conversely, if spatial patterns were the dominant feature, then the major 
clusters would be site groupings with any time groupings imbedded within 
them. We performed both "normal" (using site/times as entities and individual 
species densities as attributes to yield site/time groups) and "inverse" (using 
species as entities and their at each attributes to
density site/time as yield 
species groups) analysis. 
Separate analyses were run for ichthyoplankton, trawl, and combined sled 
and seine data based on the assumption that the behavior and particularly 
habitat preferences of the fish might change with age, and these gears sample 
different 
age groups. 
For ease of comparing the relative distribution of abundant and 
uncommon species, the mean density of each species in each cluster was 
calculated and converted to percent occurrence per cluster. These values are 
given in table form with the species and time/sites arranged to conform to the 
results of cluster analysis. 
RESULTS 
882 79
During the study samples (14 trips x sites x samples/site) were 
taken yielding 170,907 individual organisms with a total weight of 968.5 kg. 
As is typical of fish populations in other estuarine systems, a small number of 
species comprised the bulk of the population. The seven most abundant 
species accounted for 75% of the total number of individuals collected (Table 
6.1). The collecting gears were chosen to thoroughly sample the youngest 
segment of the fish population occupying the area. The mean length of all 
individuals collected with all gear types was 34.43 mm standard length. 
Cluster Analysis 
Dendrograms from the three sets of cluster analyses are presented in 
-
Figures 6.1 6.6. Each of the time/site dendrograms was separated into three 
or four major groups by dividing the dendrogram near the highest levels of 
dissimilarity. This created time/site clusters which had maximum differences in 
species composition. Species dendograms were generally divided into 5-7 
groups. The correspondence between site/time groups and species groups are 
-
shown in two-way tables (Tables 6.2 6.4). 
There were two general patterns which were common to all three data 
sets. The most significant of these was that temporal patterns dominanted. 
The strength of the temporal pattern varied among gear types. Time groupings 
were in the seine-sled data and weakest in the
strongest ichthyoplankton. 
Three "seasons" are indicated by the fish data: November through January; 
March through June, and July through October. Placement of February and 
to a lesser extent the June samples varied somewhat by gear type. These 
three "seasons" were relatively consistent between the two years despite 
significant differences in salinity. The second generalization was that spatial 
were a minor factor in the groupings. Even within the major
patterns 
seasonal the primary factor separating minor clusters was time. In 
groups 
most when collections from several different months are in one major
cases, 
divisions within that cluster would the months
cluster, the minor separate 
rather than producing separate station groups which include collections from 
several months. 
Ichthvoplankton 
This was the least "seasonal" of the data sets. Four major groups were 
identified in the dendrogram (Fig. 6.1) for the ichthyoplankton data: 
Group I contains most of the sites from OctBs, NovB4, DecBs, FebB6, and 
AugB6 as well as a few samples from other months throughout the year. All 
of the samples in this large group had no larvae (Table 6.2). In essence, there 
are few planktonic fish larvae in the Lavaca River delta during the fall 
through mid-winter (October through February). It is noteworthy that only 
two JanBs sites (85 and 633) are in this group. The other JanBs sites had 
ichthyoplankton and in fact, ichthyoplankton were relatively abundant in JanBs 
samples. 
Group II contains primarily collections from the river and the upper lakes 
(603 and 613) during JanBs, MarBs, AprBs, and AprB6. Average salinity for 
this group was relatively low at 4.0 ppt and average temperature (16.6°C) was 
the lowest of all groups. Group II was characterized by relatively high 
densities of Gulf menhaden, striped mullet, tidewater silverside and white 
shrimp and low densities of most other species. 
of sites from JunBs JanB6
Group 111 is 'Composed primarily MayBs, (no 
sites), JulBs sites 45 and 603, plus the NovB4 and DecBs samples with fish’. 
is low and
Average salinity (3.6 ppt) average temperature (23.8°C) is moderate. 
Densities of bay anchovy, rough silverside, and Atlantic croaker are relatively 
high in this group. Densities of gulf menhaden, and brown shrimp are relatively 
low and white shrimp are absent. 
Group IV contains most of the sites from AprB6, JunB6, JulBs, and the 
AugB6 sites with fish. Average salinity (10.9 ppt) is higher here than in the 

other groups as is temperature (26.0°C). Several species had their highest 
densities in this group, especially pinfish, naked goby, and brown shrimp. 
Groups 111 & IV share similar months. They basically differ in containing 
sites from different years. Differences in species composition and abundance 
were substantial. Group 111 had higher bay anchovy and Atlantic croaker 
densitites whereas Group IV had higher densities of Gulf menhaden and both 
white and brown shrimp. Salinities were much higher at sites in Group IV 
except for JulBs. It is interesting to note that the lowest salinity JulBs sites 
(45 and 603) are grouped with low salinity Group 111. 
Sled-Seine 
The major clusters derived from the dendrogram from sled-seine samples 
(Fig. 6.3) represent very discrete time groups. In only two cases was a 
time/site placed in the "wrong" seasonal group, in spite of the fact that there 
were substantial salinity differences between similar time periods in the two 
years. Three major time/site groups were identified from the dendrogram. 
Group I contains sites from Novß4, Decßs, and Janßs. This has the
group 
and
highest density of various species of killifish of striped mullet (Table 6.3) 
8 
Atlantic
but has the lowest-catches of many other species; notably croaker. 
Gulf menhaden, and brown shrimp. Approximately one half of the red drum 
occurred in this group but red drum were relatively rare throughout the entire 
study in all gear types. 
Group II contains sites from FebBs, MarBs, AprBs, AprB6, MayBs. This 
group has the highest density of several of the most abundant species 
including Gulf menhaden, brown shrimp, Atlantic croaker, blue crab, and 
southern flounder. The highest density of some less common species, such as 
pinfish, red drum, sand seatrout and freshwater shrimp occurred here. Most of 
these species are offshore winter spawners. 
Group 111 consist of sites from JunBs, JunB6, JulBs, AugBs, AugB6, and 
OctBs. The highest abundance of some less common species including 
and
leatherjacket, spotfin mojarra, blackcheek tonguefish, scaled sardine 
occurred in this These are species which invade
group. typically upper 
estuarine areas in warm weather as older juveniles (i.e. not postlarvae). This 
group also has the highest density of white shrimp and bay anchovy. 
Differences in temperature among the groups is clearly reflected in the 
temporal nature of with in of I to
the groups, a range means 10.9°C in Group 
111. Mean the from in
28.3°C in Group salinity among groups ranges 4.4 ppt 
Group I to 9.1 ppt in Group 111. 
There is no evidence of a salinity signal in these data. 
Trawl 
The the the
temporal pattern in major clusters is obviously major factor 
here but it is not as dominant as in the sled-seine data (Fig. 6.5). 
Group I consists of essentially all the sites from Julßs, Augßs, Augß6, and 
9 
Octßs. The highest densities "of many species in the trawl collections are in 
several
this group including postlarvae and juveniles of spring-summer spawners' 
such as sand seatrout, silver perch, and bay anchovy (Table 6.4). This group 
also has of older and adults of species in the
high density juveniles caught 
upper estuary in warm months including hogchoker, lined sole, and least 
puffer. 
Group II contains some of the sites from AprB6, MayBs, JunBs, and JunB6 
there are no collections from stations 45 or 65 in the The
except group. 
highest densities for most winter spawners like Atlantic croaker. Gulf 
menhaden, brown shrimp, spot, and Southern flounder were in this group. 
There were relatively low densities of white shrimp, various species of killifish, 
and gizzard and threadfin shad in this group. 
Group 111 consist of all sites from NovB4, DecBs, and FebBs plus stations 
45 and 65 from AprB6, JunBs, and JunB6. While densities of most species are 
at intermediate levels in this group, a few species, particularly white shrimp 
and bighead searobin had relatively high densities here. Several species had 
relatively low densities, especially Atlantic croaker, brown shrimp, and spot. 
Group IV was made up primarily of sites from JanBs, MarBs, (AprBs, and 
two sites (45 and 633) from MayBs). The highest densities of striped mullet, 
threadfin and gizzard shad, tidewater silverside, freshwater shrimp, blue crab, 
and several species of killifish were in this group. The lowest densities of 
some of the most abundant species, especially brown shrimp, white shrimp, and 
sand seatrout occurred here. 
Groups I and II had higher mean salinity and temperature than groups 111 
and IV. 
10 
Two groupings in the trawl data might indicate a salinity effect in the 
fish population. In the first situation. Group IV (JanBs MarBs AprBs) and 
Group II (AprB6 MayB6 JunBs and 86) share April collections from two 
years and two May sites are in group IV (Fig. 6.3). Average salinity is low in 
Group IV (2.3 ppt) and relatively high in Group II (12.4 ppt). Species densities 
are quite different between groups. Group IV has much higher densities of 
threadfin and gizzard shad and several species of killifish as well as higher 
densities of freshwater shrimp, blue catfish, blue crab and striped mullet. 
Group II had much higher densities of Atlantic croaker, brown shrimp, spot, 
and sand seatrout among others. These species differences appear to be 
related more to temperature than salinity. Water temperature in April 1985 
was 3 degrees cooler than April 1986. The cool April was grouped with cooler 
months of January and March, while the warmer April grouped with the 
warmer months of May and June. The species differences described above 
reflect this difference rather than
temporal a salinity effect. Additionally, low 
and high salinity collections from June 1985 and 1986, respectively, are in the 
same group (Group II). 
Size Distributions 
Cluster analysis provides a clear picture of seasonal patterns in the fish 
population in the Lavaca River delta and would have shown obvious spatial 
patterns if there were any. Much additional information concerning the 
organisms utilizing the delta can be gained by examining their size distribution 
over time. More than 50% of the species captured in the study are not 
permanent residents but are in the area for only part of their life cycle. The 
vast majority of these transient species are in the area during the early stages 
will be
of their life and use the area as a "nursery". The following discussion 
limited to the utilization of the area as a nursery by the dominant species or 
those species of commercial or recreational importance. 
Tables 6.5 to 6.8 show the mean standard length for each of the 23 most 
abundant species (plus spotted seatrout) for each month. The data are pooled 
-
over all stations and presented by gear type. Tables 6.9 6.12 give the mean 
abundance for each species in the same format. This presentation allows an 
examination of the seasonal size trends for each species. 
The smallest specimens were caught, obviously, in the ichthyoplankton 
samples. From Table 6.5 it can be seen that the very smallest individuals 
represent those species which spawn in the study area. These include clown 
goby, tidewater silverside, and bay anchovy. Bay anchovy eggs were common 
in the study area during the summer. This table also reveals that several 
species which spawn in the lower estuary or offshore move into the Lavaca 
River delta while still in the planktonic Atlantic croaker. Gulf
stage. 
menhaden, brown and white shrimp, and blue crab fall into this 
category. 
There are several species whose demersal postlarvae or juveniles were 
relatively common in the study area but were rare or absent from the 
ichthyoplankton samples. Species such as southern flounder, spot, sand 
slower
seatrout, and silver perch apparently move up the estuary at a rate 
and, therefore, have grown substantially prior to arrival in the delta. Another 
interesting situation is with spotted seatrout which is known to spawn in 
estuaries but was never taken in our plankton samples, even though several 
were taken with both sled and seine. This indicates that spotted seatrout do 
not spawn in the study area and that planktonic larvae do not disperse rapidly 
up-estuary from the lower-estuary spawning sites. 
and taken at the time and at the
Sled samples seine samples were same 
same sites and capture roughly the same size individuals. Data from the sled 
shows a better representation of time of recruitment of the youngest (smallest) 
individuals into the nursery habitat, especially when the period of recruitment 
is protracted, whereas the seine data reflects the initial period of recruitment 
but subsequently reflects growth in the cohort, masking continual recruitment 
of small individuals. 
Mean lengths of fish from the seine and sled data (tables 6.6 and 6.7) 
show three of larval recruitment into the Lavaca River delta.
general patterns 
The most dominant pattern is the arrival of postlarvae of fall and winter 
spawners. Out of 11 species which show a clear change (increase) in size for 
the population over time, the initial recruitment time for seven of those is the 
to
November January period (see Fig. 6.7 as an example). Postlarvae of the 
remaining four species initially arrive in the delta in early to mid-summer. 
The final pattern is shown by those species which show essentially no change 
in size over time. This pattern (or lack of pattern) is seen in species which 
in
are only captured occasionally, but is also seen common resident species 
with small adult size. This is most obvious in bay anchovy which clearly 
spawns in the summer based on ichthyoplankton data but has essentially the 
same mean length throughout the year due to the dominance of adults in the 
collections. 
A uniform pattern of growth can be seen for the winter spawners from 
initial recruitment in the late winter throughout the summer until large 
individuals are no longer caught in the seine in the late summer and the next 
year’s recruits arrive in the fall (see Fig. 6.8 as an example). The departure 
of larger fish is difficult to interpret. Although all of these species will leave 
the delta area and return to" the spawning area or adult habitat, the size 
selectivity of the seine makes it impossible to determine for most species' 
delta evade the will
whether they have left the or simply net. This be 
addressed further in connection with the trawl data. 
The temporal pattern in size distribution is less obvious for most species 
in the trawl data (Table 6.8) than in the seine and sled data. This is due 
primarily to the under representation of the smaller individuals in the trawl, 
the of a 6.4 mm liner. The lower abundance of smaller
despite presence 
individuals in the trawl may also represent intraspecific differences in habitat 
preference by different size classes. 
Results of both trawl and sled-seine cluster analysis show the year is 
roughly divided into three "seasons" based on species composition. Species 
which are using the delta as a nursery are influential in developing these 
-
seasonal patterns. "Winter" (November February) is a period of low diversity 
and density of fishes using the delta as a nursery area. Striped mullet is the 
only species whose highest density consistently occurs in the January-February 
size
period at a mean of about 23 mm. They grow rapidly through the spring 
and
and summer though striped mullet are relatively common in the study area 
they are rare in our samples due to net avoidance. 
"Spring" is the period of highest density of fishes in the nursery area 
with the young of fall-winter spawners predominating the catches. The two 
dominant species taken during this time are Atlantic croaker and Gulf 
menhaden. Atlantic croaker initially arrive in the delta in the December to 
February period but their highest densities are in March and April in the seine 
collections (Fig. 6.7) and in April to June in the trawl collections. The 
earliest arriving individuals 15-20 mm and the cohort uniformly
average grows 
to about 70 mm in July wherf they either leave the delta or successfully avoid 
our collecting gear (Fig. 6.8). Gulf menhaden had a quite similar abundance 
with initial arrival of the postlarvae in November to February and peak
pattern 
densities of juveniles in March to June. The slow increase in mean length of 
recruitment
menhaden in the seine data suggest a prolonged period; presumably 
due to an extended spawning period in this species. Brown shrimp appear to 
have two recruitment periods, one in late winter-early spring (February-May) 
and the other in late summer (August-October). The abundance data suggest 
that the late summer recruitment period is less important than the one in the 
spring. Red drum, blue crab, southern flounder and pinfish also exhibit this 
winter to spring overlap in nursery utilization. Southern flounder was 
something of an anomaly compared to other species in the delta in that they 
were caught primarily with the trawl and were relatively uncommon in the 
were
sled-seine samples. All the previously mentioned species taken commonly 
in both shoreline and open water samples. The smallest southern flounder 
were in the 12-17 mm range in the December to January period and grew to 
70-80 mm in August. 
Several species of recreational or commercial importance were at their 
highest density during the "summer-fall" season but most were not as abundant 
as several of the "spring" species. Spotted seatrout were collected almost 
exclusively during this season and were only taken in shoreline collections at a 
size of 15-30 mm. White shrimp arrive in the delta in May to July at 14-18 
mm. Their highest densities are typically in August and they leave the delta 
in October November at 50-60 mm.
or 
Comparisons with other studies 
Several studies dealing with macro-invertebrates and fishes have been 
done in the Lavaca Bay area. Results from most of these investigations are in 
reports to government agencies or private firms and were unavailable to the 
author (i.e. Blanton et al. 1971, Mackin 1971, and Lyons 1973; all cited in 
Gilmore et al. 1976). Gilmore et al. (1973) used nonreplicated-10 minute trawls 
at 7 sites in a 30 month survey of fishes and invertebrates in Lavaca Bay. 
They reported that fish densities were higher in the spring and summer and 
lower in the winter, which essentially agreed with our findings. The list of 
eight most abundant species essentially agrees with ours, though not quite in 
the same order. The major discrepancies are due to our inclusion of shoreline 
samples (i.e. grass shrimp and tidewater silversides). They found no 
correlation between freshwater inflow and the occurrence of nekton in their 
samples. 
Moseley and Copeland (1974) reported on a long-term study of nekton in 
Cox Bay, a portion of lower Lavaca Bay, in relation to the construction of an 
electric generating station. They showed a strong seasonal pattern in the fish 
population structure with the lowest densities in the winter. They examined 
the salinity relationships for 11 selected species and found that most exhibited 
no relationship; however. Gulf menhaden, sand seatrout, hardhead catfish, and 
Atlantic croaker decreased in abundance with increasing salinity while bay 
squid increased with salinities > 12 ppt. 
The results of these two studies concur with our conclusions that 
seasonal patterns are the dominant feature of fish populations in Lavaca Bay. 
These seasonal patterns are quite consistent year to year for each species and 
are minimally affected by short term variations in freshwater inflow. 
16 
A report by Texas Department of Water Resources (TDWR 1980) utilizes a 
more long-term data set to examine the influence of freshwater inflows on 
fisheries production. A complex stepwise multiple regression model was used 
seasonal freshwater inflows with various components of 1962
to compare the 
through 1976 inshore commercial fisheries harvest. These analyses indicated 
that all fisheries harvest components except blue crab were positively related 
to April-June inflows and negatively related to July-August inflows. The 
numerous fisheries components examined yielded a variety of responses to 
inflows for other It shown that when inflow needs of the
seasons. was 
fisheries components are similar, the components reinforce each other, but 
when they have different responses, management decisions must be made to 
balance divergent needs of the various components or preference must be given 
to 
one particular component. 
Salinity relationships 
Direct comparison of the relationship between salinity and the density of 
three abundant species was made through calculation of least squares 
regression. The results of these analyses present difficulties in interpretation. 
all
Table 6.13 shows statistically significant relationships (P > .0003) for three 
analysis. There is positive relationship with salinity for brown shrimp and a 
negative relationship for Atlantic croaker and Gulf menhaden. The is
difficulty 
all
that the R-square values are quite low. The highest R-square value was 
for brown shrimp = 0.0496) but this still indicates that variation in salinity 
accounts for less than 5% of the variation in brown shrimp density. Plots of 
these data ( Figs. 6.9-6.11) clearly show the scatter of the data about the 
calculated linear relationship. This indicates that although there is a significant relationship between"salinity and the density of these species, the 
relationship is relatively unimportant since greater than 95% of the variability 
in density is still unexplained. 
CONCLUSIONS 
The primary factor influencing changes in fish species composition in the 
Lavaca River delta is the sequential arrival and departure of a variety of 
postlarval and juvenile fish and invertebrate species. These fishes are moving 
into the delta from the area in which they were spawned, generally some 
distance from the delta in the lower estuary or from offshore. Most species 
depart from the delta after six to eight months. Those species which remain in 
the delta for a longer period grow rapidly and are ultimately able to avoid our 
which size
collecting gears, are highly specific. Spawning periods are relatively 
short for most species, in some cases only a month or two, but seldom more 
than six months, and are fairly consistent year-to-year. This results in quite 
discrete and relatively predictable pulses of various species entering and 
leaving the delta, producing the strong temporal pattern in the data. Salinity 
(as a surrogate for freshwater inflow) effects are seen only as a perturbation 
within these major temporal patterns and is not the major driving force 
regulating the community composition of the fish in this system on a short 
term basis. A significant, long-term alteration of freshwater inflow could have 
an effect on the overall functioning of the biological system and may indeed 
influence the relative value of the delta as a nursery, either to an individual 
species or the fish community as a whole. 
Our data show that the Lavaca River delta is utilized extensively as a 
nursery area by most estuarine dependent species which are of commercial or recreational importance in the western Gulf of Mexico. There are also 
numerous other species, many of which are important components of the food-
web leading to commercial or recreational species, utilizing the delta as a 
nursery area. The spring-early summer period (February through June) has the 
the
greatest diversity of species and the highest biomass due to preponderance 
of winter spawners whose offspring utilize the estuary as a nursery. 
Conversely, the fall-early winter period has the lowest diversity due to small 
whose larvae move to the
number of summer spawners upper estuary. 
The seasonal is a reflection of spawning times of those species
pattern 
utilizing the delta as a nursery area. In general, the "seasons" reflect the 
juveniles of winter spawners in March-June; spring and early-summer spawners 
in July-October. The low number of species spawning in late summer are 
in low the
reflected the relatively diversity of November-February period. 
even
Both diversity and density of the fish community would be more reduced 
during this period were it not for the occurrence of several species of killifish 
(Cyprinodontidae) which are apparently driven from their preferred habitat in 
submerged marsh by cold and/or low water levels during the winter. 
REFERENCES 
Blanton, W.G., T.J. Culpepper, H.W. Bischoff, A.L. Smith, and C.J. Blanton. 
1971. a study of the total ecology of a secondary bay (Lavaca Bay). 
Final Report, Aluminum Company of America. 306 
pp. 
Clifford, H.T. and W. Stevenson. 1975. An introduction to numerical 
classification. Academic Press, New York, NY. 229 pp. 
Lance, G.N. and W.T. Williams. 1967a. A general theory of classificatory 
sorting strategies. I. Hierarchical systems. Comput. J. 9:373-380 
Moseley, F.N. and BJ. Copeland. 1974. Final report-Ecology of Cox Bay, Texas 
1969-1973. Central Power and Light Company, Corpus Christi. 164 pp. 
Romberg, H.C. 1984. Cluster Analysis for Researchers. 344p. Wadsworth Inc., 
London. 
Sneath, P.H.A. and R.R. Sokol. 1973, Numerical Taxonomy. W.H. Freeman and 
Co., San Francisco, CA., USA. 573 PP. 
TWDB. 1980. Lavaca-Tres Palacios Estuary; A study of the influence of 
freshwater inflows. Texas Water Development Board. LP-106. Austin, 
Texas. 
APPENDIX I 
ranked
the
total abundance. Mean length, 	total weight with all 
-
by 
abundance 
combined. 
and total were computed 
and
dates, stations, gear types 
Total Abundance 
Mean Total 
Length Weight (mm) (gm) 
Table 6.1 List of species taken during study 

1  GULF MENHADEN  29.9  231375  50185  
2  BAY ANCHOVY  26.9  255059  47423  
3  ATLANTIC CROAKER  37.6  65563  21701  
4  GROOVED SHRIMP  36.1  64879  14602  
5  GRASS SHRIMP  - 2666  10692  
6  WHITE SHRIMP  39.2  15847  9971  
7  SPOT  39.4  7061  3210  
8  TIDEWATER SILVERSIDE  32.7  2547  2332  
9  BLUE CRAB  20.9  35584  2184  
10  STRIPED MULLET  35.1  6824  2063  
1 1  SHEEPSHEAD MINNOW  27.0  1619  1222  
12  ROUGH SILVERSIDE  21.4  105458  578  
13  SAND SEATROUT  50.1  1704  525  
14  BLUE CATFISH  39.8  26588  486  
15  PINFISH  31.4  21559  483  
16  FRESHWATER SHRIMP  - 1442  4 17  
17  NAKED GOBY  17.8  3599  341  
18  SOUTHERN FLOUNDER  37.3  1700  338  
19  GULF KILLIFISH  43.6  630  316  
20  HARDHEAD CATFISH  45.9  3416  230  
21  CLOWN GOBY  8.0  99089  224  
22  SILVER PERCH  32.6  187  219  
23  GAFFTOPSAIL CATFISH  51.4  2216  153  
24  RHITHR. HARRISII  7.1  645  152  
25  ATLANTIC THREADFIN  60.3  682  111  
26  BAY WHIFF  36.3  153  66  
27  HOGCHOKER  42.8  413  58  
28  MOSQUITOFISH  18.7  11  54  
29  BLACKCHEEK TONGUEFISH  51.1  101  4 4  
30  LINED SOLE  29.1  63  43  
31  DIAMOND KILLIFISH  21.1  12  42  
32  LADYFISH L  26.6  68  4 1  
33  SPOTTED SEATROUT  23.0  100  37  
34  THREADFIN SHAD  53.2  85  36  
35  LEAST PUFFER  26.3  4 1  35  
36  BIGHEAD SEAROBIN  33.2  46  29  
37  GULF PIPEFISH  60.3  10  26  
38  GIZZARD SHAD  73.3  255  23  
39  MUD CRAB  10.0  6  17  
40  STRIPED BLENNY  3.3  2364  16  
4 1  SPOTFIN MOJARRA  45.3  51  15  
42  GOBY SP.  5.5  613  12  
43  THUMBSTALL SQUID  53.3  131  12  
44  SCALED SARDINE  29.1  4  11  
45  RAINWATER KILLIFISH  24.7  3  10  
46  SKILLETFISH  24.8  9  10  
47  SPECKLED WORM-EEL  45.0  5372  10  

Table  6.1 (continued)  
48  DARTER  GOBY  17.4  85  8  
49  LADYFISH  A  50.1  45  8  
50  BLACK  DRUM  28.4  286  7  
51  ATLANTIC  MIDSHIPMAN  39.3  25  6  
52  RED  DRUM  31.7  129  6  
53  SHEEPSHEAD  4  1.2  64 1  6  
54  LEATHERJACKET  51.5  12  5  
55  MENIPPE  MERCENARIA  12.4  4  5  
56  PETROLISTHES  ARMATUS  6.6  1  5  
57  INSHORE  LIZARDFISH  33.8  40  4  
58  XANTHIDAE  SP.  5.0  0  4  
59  ATLANTIC  NEEDLEFISH  76.0  2  3  
60  BAYOU  KILLIFISH  36.3  3  3  
61  CHAIN  PIPEFISH  31.0  4  3  
62  PIGFISH  15.0  0  3  
63  SAILFIN MOLLY  28.0  1  3  
64  GREEN  GOBY  26.0  1  2  
65  SOUTHERN  KINGFISH  80.0  17  2  
66  STRIPED  ANCHOVY  40.0  1  2  
67  ATLANTIC  BUMPER  25.0  0  1  
68  BLACK  CRAPPIE  120.0  58  1  
69  CENTRARCHID  SP.  20.0  0  1  
70  CLINGFISH  10.0  0  1  
71  CODE  GOBY  16.0  0  1  
72  CRAVALLE  JACK  96.0  25  1  
73  EURYPANOPEUS  DEPRESSUS  11.3  1  1  
74  GULF  KINGFISH  11.0  26  1  
75  GULF  TOADFISH  11.0  46  1  
76  LONGNOSE  KILLIFISH  28.0  0  1  
77  MOTTLED  MOJARA  64.0  . 0  1  
78  PAGURID  SP  6.0  0  1  
79  SHRIMP  EEL  41.0  80  1  
80  SOUTHERN  HAKE  62.0  3  1  
81  STAR  DRUM  9.0  0  1  
82  STRIPED  BURRFISH  3.0  0  1  
83  SUNFISH  SP.  61.0  6  1  
84  WHITE  CRAPPIE  170.0  150  1  

data.
Figure 6.1 Site/time dendrogram from cluster analysis of ichthyoplankton 
Figure 6.1 (continued) 
Figure 6.2 Species dendrogram from cluster analysis of ichthyoplankton data. 
from cluster analysis of combined sled-seine data.
Figure 5.3 Site/time dendrogram 
Figure 6.3 (continued) 
combined sled seine data. 
Figure 6.4 Species, dendrogram from cluster analysis of 
Site/time dendrogram from cluster analysis of trawl data.
Figure 6.5 
Figure 6.5 (continued) 
of trawl data. 
Figure 6.6 Species dendrogram from cluster analysis 
32 
Table 6.2 Percentage of occurrence in each tlme/site group for 
each  species  In the  icthtyoplankton  data. Lines  defining  the  
boxes  were  derived from  the dendrogram.  
Time/site Groups  
I  II  III  IV  
Bay  Anchovy  1  89  10  
Clown  Goby  99  1  
Rough  Silverside  1  90  9  
Blue  Crab  5  50  5  
Gulf  Menhaden  72  5  23  
Brown  Shrimp  1  16  83  
Naked  Goby  100  
Atlantic Croaker  6  89  5  
Striped Mullet  100  
Speckled  Worm-eel  100  
Pintish  100  
Least  Puffer  27  73  
Tidewater Silverside  58  12  30  
White  Shrimp  69  31  
Striped Blenny  35  65  
Mean Salinity  8.7  4.0  3.6  10.9  
Mean  Temperature  22.8  16.6  2 3.8  26.0  

in each tirae/site group
occurrence
Table 6.3 Percentage of for 
in the combined sled-seine data.
each species 
Leatherjacket Mud Crab Hardhead Catfish 
Clown Goby Spotfin Mojarra Blackcheek Tonguefish Seatrout
Spotted 
Ladyfish (adult) 

Scaled Sardine Lined Sole Skilletfish 
Black Drum Diamond Killifish Red Drum 
Gulf Pipefish Pinfish Southern Flounder Bay 
Whiff Rhithr. 
harrisii 
Darter Goby Blue Catfish Freshwater Shrimp 
Rainwater Killifish Mosquitofish Ladyfish (larvae) 
Atlantic Croaker Blue Crab 
Grass 
Shrimp Spot Striped Mullet Brown Shrimp 
Tidewater Silverside Gulf Menhaden Bay Anchovy Sheepshead Minnow 
Gulf Killifish Silver Perch 
Sand Seatrout 
White Shrimp Naked Goby Silverside
Rough 
Mean Salinity 
Mean Temperature 
Time/Site Groups 
I II III 
100 34 
62 
100 100 82
18 
59
21 7 
21 93 
100 100 100 
15 85 
23 77 98 50 
50 
21
3643 
3
4 94 
4 90 11 45 
96 
26
27 
78 30 
22 
70 
19
81 
31 4 
8
61 
2 96 39 
98 
1
60 
26
31 43 
7
3260 
3
89
7 
1
93 6 
25 62 19 
70
4 
20 
15
75
10 59
1
18 
1
98 1 
1
2
97 
79
20 
10 99 
90 
1 28 20 
51 
6 94 
4.4 6.8 9.1 
22.3 28.3
10.8 
34 
Table 6.4  Percentage  of  occurrence  In each  time/site group  for  
each species  in the trawl  data.  
Time/site Groups  

I  II  III  IV  
Bighead  Searobin  6  89  5  
Naked  Goby  100  
Rhithr.  harrisii  9  13  43  35  
Mud  Crab  100  
Hogchoker  40  20  2  39  
Atlantic Midshipman  70  30  
Lined Sole  66  27  7  
Least Puffer  94  6  
Pinfish  13  81  2  3  
Thumbstall Squid  11  89  
Blackcheek  Tonguefish  38  - 28  34  
Bay  Whiff  24  68  8  
Atlantic Treadfin  7  66  27  
Hheepshead  Minnow  1  8  92  
Gulf  Killifish  2  98  
Threadfin Shad  17  2  81  
Gizzard  Shad  100  
Tidewater Silverside  12  88  
Sheepshead  16  84  
Striped  Mullet  7  15  78  
Atlantic  Croaker  2  67  6  
Brown  Shrimp  12  81  6  
White  Shrimp  43  56  
Gafftopsail  Catfish  100  
Silver Perch  66  34  
Hardhead Catfish  63  36  1  
Sand  Seatrout  36  52  7  6  
Blue Catfish  63  9  1  26  
Freshwater Shrimp  1  3  6  90  
Bay  Anchovy  34  35  17  IT  
Blue  Crab  7  23  20  58  
Gulf  Menhaden  6  47  16  31  
Southern Flounder  8  52  26  14  
Spot  3  83  6  14  
Grass  Shrimp  8  10  81  
Mean Salinity  10.0  12.4  6.2  2.3  
Mean  Temperature  29.2  27.1  19.5  16.1  

,d.  2*3 5,7  6.3 2,2 0.7  *  *  •  *  10.4  1.0 2.9  • •  1.4  18.3 1.1  9.2  
s  
Average  13.3 15.5 0.0 11.7 11.6 4.5 0.0 0.0, 0.0 0.0 26.9 0.0 3.5 12.8 7.5 0.0 30.0 0.0 0.0 8.0 0,0 0.0 16.3 9,4  14.6  
August  0.0  
June  20.5  20.5  
April  5.3  23.0 11.9  25.2  12.0  4 . 4 11.0  13.3 8.0  
February  20,5  13.0  16.8 5.3  
December  12.0 20.3  16.2 5.9  
collections.  October  17.0  3,6  10.3 9.5  
7'  
icht hyoplankton  July August  12.2 9 .  15.0 4.0 7.0 10,4 4.0  37.0  6.1  8.5 9.0  13.8 8.0 12.0 2.6  
the  June  15.8  8,1 13.8 4.5  51.0  7,7  7 2 9.0  14.6 15.1  
for  
combined,  May  14.3  13.0 7.8 5.5  20.0  6.1  11.1 5.7  
stations  April  24.8  16.1 12.4  23.5  3.5 14.0 12.4  15.4 6.7  
all  March  8.0 13.0  21.4  5.0  11.9 7,2  
by species,  January  21.1  23.2  29.0  8,0  37.4  21.6 11.0  
length (mm)  November  | 1 20,0 |  |  |  |  |  | |j 20.7 |  |  |j 12,0  |  | 31.0 |  |  |j  |  |  (  19,5 7. 4  
6.5 Monthly mean  SPECIES  SAY ANCHOVY BLUE CATFISH SLUE CRAB ' BROWN SHRIMP CLOWN GOBY FRESHWATER SHRIMP GAFFTOPSAIL CATFISH GRASS SHRIMP GULF KILLIFISH GULF MENHADEN. HARDHEAD CATFISH NAKED GOBY PINFISH ROUGH SILVERS1DE SAND SEATROUT SHEEPSHEAD MINNOW SILVER PERCH SOUTHERN FLOUNDER SPOT SPOTTED SEATROUT STRIPED MULLET TIDEWATER S1LVERSI0E WHITE SHRIMP  Average s.d.  
Table  

s.d.  27.8 2.8 43.6 7.9 14.1  11.9 7.6 42.4 8.1 26.1 11.9 6.2 3.0 20.6 11.1 24.1  10.4 23 4 7 4 14.7  20.2  
Average  <4.3 25.8 40.0 15.6 32.3 0.0 0.0 54.5 0.0 44.3 27.4 43.2 20.0 35.9 40,8 41.7 26.4 35.6 35.2 40.8 23.7 42.7 33.7 35.8  33.7  
August  100.0 28.9  12.2 41.6  43.7 13.0 34.0 74.5 33.3 45.8  55.5  55.8 20.0  34.3 42.2  42,3 23.0  
June  80.3 25.1 57.0 34.3 <7.7  32.8 95.0  65.5 28.1  18.3  50.0 13.8 55.6  28.4  45,1 23.8  
April  41.7 28.3 13.0 30.5 40.4  22.5  27.4  42.6 38.0  29.0 41.6 10.0  30.4 11.1  
February  19.0 31.1 12.0 9.5 15.3  60.0 21.6  15.0 14.5 35.0  24.0  19.0 17.0  24.4 26.1  22.9 12.4  
December  21.4 23.6  8.6 16.0  33.1 21.7  18.0  22.7  11.0  20.5 31.7 51.8  23.3  11.4  
October  13.5 23.5  . 6.0 50.5  84.0 16.0 11.0 39.9  37.0 96.0  54.1  39.2  29.9  
collections.  August  63.0 24.6 12,5 12.0 25.9  54.5  26.0 33.3 13.5 7.7  49.8 29.7 60.0  16.4 45.8 36.2 27.4  31.7  17.5  
seine  July  74.8 27.1 33.0 16.1 41.1  56.0 38.5 10.7 12.5 80.0  34.8  47.5  81.0 36.7 71.2 35.8 29.7  42.7 22.7  
the  June  64.3 24.8 40.0 10.5 52.5  31.0  17.5 56.0 34.8 41.5  27.6  73.0 18.5 66.1 23.1  38.7  19.6  
for  
combined,  Hay  44.3 23.2  12.5 17.8 28.8  49.0 22.2  33.0 38.0 52.8 36.6  10.5 42.5 59.9  34.9 28.6  33.4 14.2  
stations  April  37.6 27.3 139.6 15.8 17.6  56.3 22.2  25.3 17.0 61.4  36.6 46.5  39.7 50.7  42.4 31.7  
all  March  25.5 28.8  15.6 13.6  39.0 22.4  23.0 14.3  30.0  28.4  25.6 35.4  25.1 8.0  
by species,  January  17.1 21.4  13.0  34.3 22.3  20.0  26.6  16.1  23.7 31.9  22.6 6.8  
length (mm)  November  | 17.8 | 23.5 |j  16.0 | 29.4 |  |  |  |  ( 45.0 | 21.7 j  | 18.5 | 12.0 |j  | 25.1 |j  | 12.3 |  [ 21.0 | 28.5 | 43.0  24.1 10.3  
6.6 Monthly mean  SPECIES  ATLANTIC CROAKER SAY ANCHOVY BLUE CATFISH BLUE CRAB BROWN SHRIMP CLOWN GOBY FRESHWATER SHRIMP GAFFTOPSAIL CATFISH GRASS SHRIMP GULF KILLIFISH GULF MENHADEN HARDHEAD CATFISH NAKED GOBY PINFISH ROUGH SILVERSIOE SANO SEATROUT SHEEPSHEAO MINNOW SILVER PERCH SOUTHERN FLOUNDER SPOT SPOTTED SEATROUT STRIPED MULLET TIDEWATER SILVERSIOE WHITE SHRIMP  Average s.d.  
Table  

¦  
s.d.  22.3 3.9 .  17.1 10.9 3.5  .  2.4  - 4.$ 15.0 .  •  S.l 1.0 12.5 19.1 6.5 .  14.2 12.7  13.2  
Average  31.7 21.5 11.0 18.5 25.7 12.8 0.0 0.0 0.0 45.2 21.2 0.0 17.5 .23.6 21.0 15.0 28.3 11.4 33.0 29.3 14.5 22.0 24.8 24.8  23.3  
August  25.5  73.0 26.1  19.7  11.9  60.0 10.0  30.4  32.1 22.6  
June  16.0 21.8  13.9 42.7  11.7 50.5 21.0  12.0 52.3 49.0 11.5  14.1  26.4 16.9  
April  34.6 17.0  11.6 24.7  19.9  22.7 32.0  38.0 34.7  11.0  24.6 9.9  
February  19.9 31.3  12.8 15.0  22.1  19.9 13.7  31.0  20.4 15.0  22.0  20.3 6.3  
December  16.0 20.4  9.4 17.7  16.8  23.4  52.0  22.2 13.8  
October  11.9 18.3  7.1 37.0 10.2  13.4  22.7  17.2 10.1  
collections.  July August  80.0 20.3 19.6  8.8 19.1 27.5 22.3 15.3  13.5 11.1  10.3  22.0  17.0 18.7  23.9 17.6 21.9 4.2  
sled  
the  June  66.0 21.5  19.9 48.4  26.0  14.9  22.3  31.3 18.7  
for  
combined,  Hay  38.1 19.0 11.0 17.9 25.5  19.0  23.4  15.0  13.7  20.3 8.1  
stations  April  28.1 25.0  13.3 15.0  20.2  23.7 18.5  25.9 22.1  40.8  23.3 7.8  
all  March  24.6 21.3  10.8 13.2  21.4  21.2 14.3  35.5  28.5 13.3  20.4 7.8  
by species,  January  0.0 - 
length (mm)  November  | 13.4 j 18.1 |  | 23.4 j 19.6 |  |  |j  | 46.2 | 19.8 |  | 15.8 | 12.5 |  |  | 23.1 |j  | 11.3 ) [ | 20.0 | 35.1  21.5 10.0  
6.7 Monthly wean  SPECIES  ATLANTIC CROAKER BAY ANCHOVY BLUE CATFISH BLUE CRAB BROWN SHRIMP CLOWN GOBY •FRESHWATER SHRIMP GAFFTOPSAIL CATFISH GRASS SHRIMP GULF KILLIFISH GULF MENHADEN HARDHEAD CATFISH NAKED GOBY PINFISH ROUGH SILVERSIDE SAND SEATROUT SHEEPSHEAD MINNOW SILVER PERCH SOUTHERN FLOUNDER SPOT SPOTTED SEATROUT STRIPED MULLET TIDEWATER SILVERSIDE WHITE SHRIMP  Average s.d.  
Table  

s.d.  18.3 4.7 37.4 10.0 14.4 2. ,5  21.5  8.5 12.7 74. Tv 3.9 23.5  13.7 2 1 22.4 23.9 22.4  36 4 25 1 17.4  26.9  
Average  47.6 35.7 28.4 30.2 49.7 25 8 0.0 52.0 0.0 59.0 41,6 65.6 27.3 52.5 0.0 55.3 30 9 44.5 46.3 65.5 0.0 44 9 64 1 52.8  45.9  
August  70.9 42.4  16.5 26.2 45.2  28.4  44.7 42.5  68.0  53.6  51.3 83.5 62.2  87.0  61.6  52.3 18.2  
June  65.3 38.5  25.7 69.5  39.1 31.9  60.8  40.0  27.0 51.5 57.6  16.5  43.6 15.4  
April  45.5 34.4  46.5 51.6  27.9 79.9 23.0 27.6  45.7 43.1  35.2  41.9  19.3  
February  32.4 28.0  16.3 39.8  26.6  25.5 72.0  26.4 24.2  53.6  34.5 20.1  
December  27.8 30.5 14.5 19.7 47.4 24.0  53.0  32.0  82.0 30.7  12.3  14.6  57.8  34.3 24.0  
October  46.0 38.7  32.2 52.0  57.9 73.0  91.0  70.3  57.6 13.7  
collections.  August  73.1 40.3 13.1 40.5 58.5  57.4  61.0 40.7  83.7  63.0 28.0 73.3 78.3 86.7  91.0  39.4  58.0 21.0  
trawl  July  74.8 39.3 15.0 40.2 58.6  70.3  48.8 19.6 31.0 68.6  52.6  78.9 76.4  47.0  62.1  52.2 19.5  
the  June  58.6 39.9  14.3 40.7 68.4  58.3 33.0  64.0  54.8  26.5 57.2 67.0  48.6 15.6  
for  
combined,  Hay  48.8 35.4 21.3 38.0 ST .7  38.6 13.6  38.1  41.6 49.0  37.0  37.6 11.9  
stations  April  41.4 34.7 134.7 34.6 35.5  31.3 256.0 29.0 31.0  38.3 36.6  86.0  65.8 83.3  
all  March  31.5 36.1 17.2 23.2 14.0  27.7  28.5 36.0  20.0 96.0  13.3  72.0  34.6 30.4  
by species,  January  26.2 20.5 17.0  27.5  53.0 25.9  22.0  32.2  16.3 83.0  16.6 48.5  31.7 21.8  
length (mm)  November  jj 36.0 | 17.0 j 21.9 j 52.6 |  |  |  ( j 65.0 | 41.2 1|j 13.0 |j 58.3 ( 32.5 j  | 52.2 j 78.1 j  j  | 85.0 | 59.3  45.6 23.5  
6.8 Monthly mean  SPECIES  ATLANTIC CROAKER BAY ANCHOVY BLUE CATFISH BLUE CRAB BROWN SHRIMP CLOWN GOBY FRESHWATER SHRIMP GAFFTOPSAIL CATFISH GRASS SHRIMP GULF KILLIFISH GULF MENHADEN HARDHEAD CATFISH NAKED GOBY PINFISH ROUGH S1LYERSIDE SAND SEATROUT SHEEPSHEAD MINNOW SILVER PERCH SOUTHERN FLOUNDER SPOT SPOTTED SEATROUT STRIPED MULLET TIDEWATER SILVERSIOE WHITE SHRIMP  Average s.d.  
Table  

s.d.  22.9 64,5  * 12.7 30.4 87.1  - - - *  94.5  0.5 51,5  - 0.0  - - - - 0.7 8.5 4.5  55.0  39  
v  
Average  14.8 51.9 0.0 6.8 26.8 53.5 0.0 0.0 0.0 0.0 67.2 0.0 17.0 1.3 38.2 0.0 1.0 0.0 0.0 2.0 0.0 1.5 15.7 4.3  30.4  
August  19  19.0  
1  
2.0  
June  
April  22  1 65  11  1  2  17,0 24.9  
2  1  
February  1.5 0.7  
December  1 16  8.5 10.6  
1  5  
October  3.0 2.8  
collections  August  4  1 7 1  2  3.0 2.5  
hyoplankton  June July  200 22  38 1 17 183 3  1 1  28 18  6 11 2  60.5 7,8 81.8 9.5  
icht  
the  May  146  2s  27  23  129  55.3 64.6  
in  
species  April  5  66  254  17 2 10  51.3 92.1  
by  
stations  March  37  1 1  148  6  1  32,3  58.4  
for all  January  59  158  1  2  2 22  41.9 56,4  
abundance  November  62  7  I  1  15.0 26. 4  
|  |  |  |  |j  |  |  |j  |j  |  |  |  |  |  |  |  |  |j  |  
6.9 Monthly total  SPECIES  8AY ANCHOVY BLUE CATFISH BLUE CRAB BROWN SHRIMP CLOWN GOBY FRESHWATER SHRIMP •GAFFTOPSAIL CATFISH GRASS SHRIMP GULF KILLIFISH GULF MENHADEN HARDHEAD CATFISH NAKED GOBY PINFISH ROUGH SILVERSIDE SAND SEATROUT SHEEPSHEAD MINNOW SILVER PERCH SOUTHERN FLOUNDER  SPOT SPOTTED SEATROUT STRIPED MULLET TIDEWATER SILVERSIDE WHITE SHRIMP  Average s ,d.  
Table  

s.d.  34 3.2 2598.6 6.4 66.3  251.6 7.2  629 2 45.3 6044.2 0.9 10 3 55 1 74 9 24.1 192.3 18.6 2.2 146 6 4.2 <57.7 112 6 879.5  1913.8  
'  
Average  252.6 3168.0 4 6 <0.8 0.0 299 3 5.7 2.0 599.5 28.8 3311.3 1.6 6.7 21.2 55.3 18 4  145.7 12.7 5.3 87.8 5.0 151 2 151.1 661.5  54 6.7  
August  2 3912 215  46  117  59  1  1 2 8 2  11 1  93 2332  389.1  1066.5  
June  3 5892 1  3  45  8269 1  5 200  11  18 37 217  129  986.9 2515.5  
April  358 1615  4  ’329  44  237 9  38  8 395  3 285 1  4 55 .1 7 54 .5  
February  453 71  1 41  689  1125 1 961  1 193 1  23  3 398  106 106  260.8 365.7  
December  168 3684  4  467  380 128 310  2  246  1  45 293 5  441.0 987.2  
October  2 9286  1  1  1 1 2 S3  4 1 10 211  797.8 2673.8  
August  3 4 2 5 8 '2 3  84  2  25 1 124  2 1  4 14  1  1 6  3 73  1341  313.1 1002.6  
collections  July  5 2129 3  15  41  567  3 13  3 37 1  3  4  2  13 29  166 1272  239.2 567.5  
June  25 5597 20 246  504  I  126  666  11 1  no  25  50  16 3 7 175  4 4 6 .1  1340.8  
seine  
the  May  190 3800 2 32  580  2  1649 2  5504  10 4  8  58  6 4 14  8  6.6  663 .3  1532.3  
in  
species  April  1194  2193  6 107  625  14  381 4  1206  1  3 7  6 82  19 45  368.3 636.4  
by  
stations  March  1586  34  432  586 3 21722  3 3  I  57  65  65  1933.1 5962.8  
for all  January  11  2  14  796 41  1181  3 1  491  51  1671 357  358.5 54 2.0  
abundance  November  318  64  79  1954  76 653  9 1  99  1303 I  313.7  536.5  
|  |  |  |  |  |  ]  |  |  |  |  |  |  |  |  |j  |  |  |  |  |  |  
6.10 Monthly total  SPECIES  SAY ANCHOVY BLUE CATFISH SLUE CRA8 CLOWN G08Y BROWN SHRIMP FRESHWATER SHRIMP GAFFTOPSAIL CATFISH GRASS SHRIMP GULF KILLIFISH GULF KENHAOEN HARDHEAD CATFISH NAKED G08Y PINFISH ROUGH SILVERS IDE SAND SEATROUT SHEEPSHEAO MINNOW SILVER PERCH SOUTHERN FLOUNDER SPOT SPOTTED SEATROUT STRIPED MULLET TIDEWATER SILVERSIOE WHITE SHRIMP  Average s.d.  
Table  

s.d.  67.1 27.4  28.8  348.8 0 7 0.5 223.0  <70.5  15.2­62.3  80.5 44.3  10.3 133.9 1.2  1.2  151.6  186.9  
Average  46.6 23.5  1.0 39.4  264.8 3 5 1.5 0.0 149.4 11.0 194.6 0.0 18.0 28.8  1.0 6 0  49.3 40.3 9.4 58.4 2.3  1 0 2.0  100.0  75.3  
August  2  10  105  15  6  9  1  1  80  25.6  30.5  
16  226  1  21  19  3 1  91 3 2  3  1262  49.9 79.2  
June  
T1  6 1  8 1219  18  8  11  2  1 3  1  116.2 6.4  
Apr  
February  64 4  30 811  310  16  6  156  1  23 361  1  148.6 149.3  
December  25 18  52 5  121  5  25  1  31.5 56.3  
October  5 3  21 78 4  52  21  26.3 ERR  
August  7  9 67  19  18  86  34.3 39.0  
collections  June July  1 1 12 86  35 22 201 181 3 1 2  71 226  1  22 43  21  3  3 437  38.6 93.2 30.1 166.9  
sled  
the  Hay  6  73  1  45  165  2  83  2  5  6  3  35.5 32.5  
in  ¦  
species  April  52  43  34  175  63  71  9 2  18 6  3  43.3 29.5  
by  
stations  March  90  17  89  137  49  1260  9  4  2 33  169.0 506.8  
for all  January  60  796  2  286.0 561.4  
abundance  November  216 24  97 72  11  4  29 $ 169  3  1 9  53.4 26.2  
|  |  |  |  |  |j  |  |  |  |j  |  |  |  |  |  |  (  |  |j  |  |  
6.11 Monthly total  SPECIES  ATLANTIC CROAKER .BAY ANCHOVY BLUE CATFISH BLUE CRAB BROWN SHRIMP CLOWN GOBY FRESHWATER SHRIMP GAFFTOPSAIL CATFISH GRASS SHRIMP GULF KILLIFISH GULF MENHADEN HARDHEAD CATFISH  NAKED GOBY P1NFISH ROUGH SILVERSIOE SAND SEATROUT SHEEPSHEAD MINNOW SILVER PERCH SOUTHERN FLOUNDER SPOT SPOTTED SEATROUT STRIPED MULLET TIDEWATER SILVERSIOE WHITE SHRIMP  Average s.d.  

’ 
Table 
s.d.  1 870.7 178.9 58 0 81.9 707.7 0.7 123.4 23.8 199.3 31.1 ' 862.2 28.0 0.5 7.5 53.7 64.0 5.8 20.8 354 .2 24.5 12.7 632.6  695.8  
June August Average  377 105 1259.9 28 509 163.3 214 40 7 12 74.8 1458 159 5 4 6.8 1.5 98.5 50.3 157.7 23.0 4 9 7.9 24.6 1.6 5.1 0.0, 53.4 37.3 5.5 20.8 136.5 0.0 15.7 11.0 37 5.2 46 358 33 326 70 12 2 2 1 73 14 2 <0 1 • 4 150 • 2 2 563  203 .1 129.1 239 .1 418.4 185.3  
April  1836 548 43 222 1 66 1560 18 1 24 34 1300 2 4  589.0 827.9  
December February  315 452 363 24 7 21 78 78 1 43 49 48 201 I 257 2 1 3 11 3 74 38 18 131 15  85.9 93.8 122.4 138.4  
October  6 60 I 7 128 17 2 1 134  39.6 55.0  
stations by specie in the trawl collections.  March April May June July August  706 1 279 122 53 62 81 93 132 218 39 32 32 21 162 147 271 208 120 45 55 12' 1 36 790 1268 730 73 112 268 8 6 29 76 481 17 1 126 2 3183 1 2 307 3 277 3 2 1 83 21 9 70 1 1 5 3 51 158 95 27 4 3 1 19 1 24 175 43 3 31 8 16 35 6 11 4 5 1 1 656 209  2 4 8 .7 <89.8 296.8 598.8 144.5 65.7 613.2 1051.9 4 79.9 1816.6 226.9 75.7  
abundance for all  November January  58 57 1 4 141 19 113 2 1 412 45 147 120 1 I 18 4 133 9 12 5 1 64 20 204 7  2 2 4 .3 94.3 55 7 .3 146.4  
Table 6.12 Monthly total  SPECIES  BAY ANCHOVY | BLUE CATFISH j BLUE CRAB | BROWN SHRIMP j CLOWN GOBY j FRESHWATER SHRIMP | GAFFTOPSA IL CATFISH 1 GRASS SHRIMP | GULF KILLIFISH ] GULF MENHADEN | HARDHEAD CATFISH | NAKED GOBY | PINFISH | ROUGH SILVERSIDE | SAND SEATROUT | SHEEPSHEAD MINNOW | SILVER PERCH | SOUTHERN FLOUNDER | SPOT | SPOTTED SEATROUT | STRIPED MULLET | TIDEWATER SILVERSIDE j WHITE SHRIMP j  Average s.d.  

Table 6.13. Results of .regression analysis of salinity and density of three species taken in the sled and seine collections. 
Species Correlation R 2 Significance Coefficient 
Atlantic -0.216 0.0444 P >0.0001 croaker 
Gulf -0.188 0.0352 P >0.0003 menhaden 
Brown 0.222 0.0496 P >0.0001 shrimp 
Fig. 6.7 Mean number of Atlantic croaker per 10m_2 by month for combined seine and sled data 
Fig 6.8 Mean length of Atlantic croaker from trawl 
and seine data for each month. 

Fig. 6.10 The relationship between salinity and density of brown shrimp. 
Fia. 6.9 The relationship between salinity and density 
Fig 6.11 The relationship between salinity and density of Gulf menhaden. 
¦"  CHAPTER 7  
STABLE ISOTOPE STUDIES  
INTRODUCTION  
There  are  two  stable  isotopes  of  carbon  and  two  of  nitrogen  with  the  
ratios:  
13 c  1.11  15 N  0.37  
12 C  98.89  14 N  99.63  

It has been known for sometime that these ratio values are slightly different 
for materials from various sources. The chemical principles which control 
these variations are well understood so that measurements of the ratios can be 
used to mechanisms of natural As a result of small kinetic
study processes. 
isotope effects in the biological carbon and nitrogen cycles the major 
reservoirs of carbon and nitrogen have fairly distinct isotope ratios. Modern 
mass spectrometers make it possible to measure variations in these ratios on a 
large number of samples at a high precision. By custom, isotope ratio data are 
reported using the 8 (del) terminology*. 
Carbon reservoirs relevant to this study include C 3 plants, phytoplankton, 
seagrasses and C 4 plants. Because these are the end members for the mixing 
model that will be used to estimate the sources of organic matter in the diet 
13 
of animals it is important to note their 6 C values as well as their abundance 
1 
"
RR 
xs 
13 
SC= X1000 R 
s 
13 12 
where R = 
C/ C of a sample
x 
l3 12 
R = C/ Cof a standard carbonate rock, PDB. 
s 
15 
A similar definition applies to 8 N where the standard is atmospheric nitrogen. The units are per mil. 
and distribution. Phytoplankton are distributed throughout the study area;
, 
13 
~
6 C for marine phytoplankton are -20. The Cz plants are mostly associated-
with the extensive Juncus marsh in upper Lavaca Bay and with other vascular 
plant detritus which is being transported downstream by the river and streams; 
13 
do not
~
8 C for Ca plants is -26. Seagrasses occur in Lavaca Bay, although 
13 
~
they do grow in Matagorda Bay; 8 C for seagrasses is -10. Spartina does 
occur in upper Lavaca Bay, but it is not nearly as abundant as Juncus; as a Ca 
13 13 
~
plant it has a 8 C of -13, Given these distributions and 8 C ranges a 
13 
good, but not perfect, 8 C tracer model can be made for the study area. 
To a first approximation a number of investigators have found that "you 
are what you eat ± 1.0 mil" applies to food webs as diverse as insects (Fry
per 
et al 1978) and African browsing animals like the kudu (Van Der Merwe, 1982). 
The opportunity for a natural tracer experiment of carbon flow in coastal food 
webs is obvious and has been undertaken by several researchers. These studies 
are reviewed by Fry and Sherr (1984), 
15 
Nitrogen isotope ratios, as expressed by 8 N, do not behave exactly like 
carbon. Rather than staying almost constant as organic nitrogen moves up a 
food 2 mil in each
chain, 6 15 N shifts to 5 per the plus direction at trophic 
level (DeNiro and Epstein 1978). The exact value of this shift is species 
dependent and is not well understood. However in a general sense the position 
of a species in a food chain will be reflected in the 6 15 N value of that 
~
species. For example zooplankton are +5, while rainbow trout are ~ +l2, in 
Lake Iliamna, Alaska. 
13 15 
The results of a two year study of 8 C and 6 N of the components of 
the Lavaca River Delta and Bay are reported and analyzed in this report. 
METHODS 
13 
Table 7.8 8 C values for 700 samples of biota,,
reports approximately 
sediment and dissolved Organic carbon. In order to interpret this data an 
estimate of error must be made. 
13 
The 8 C values were measured on a VG Micromass isotope ratio mass 
spectrometer. The measurements were made on CO2 which was prepared by 
sealed tube oxidation, sample plus cupric oxide in a pyrex tube. Routine 
duplicate analyses and daily calibration checks indicate that the analytical 
error for a single analysis does not exceed ± 0.2 per mil. As may be 
anticipated this is considerably less than the variability associated with 
biological samples. Table 7.1 provides two examples of the range associated 
with organisms taken in the same trawl haul. 
These animals, like most in this study, are small and respond quickly to 
changes in diet. The 1.0 to 1.5 per mil variability reflects the random 
utilization of isotopically dissimilar diet items by these animals. Captive 
13 
shrimp offered a single diet resemble each other in 8 C values to ± 0.3 
(Anderson et al 1987). 
Samples were taken for isotopic studies during the regular sampling 
periods, refrigerated, returned to the laboratory and kept frozen until 
processed. The sampling schedule is shown in Table 7.2. 
RESULTS 
The major goal of the carbon isotope study was to assess the level of 
utilization of river/marsh derived organic matter by biota in upper Lavaca Bay 
and whether that extends toward the
to establish a gradient of organic signal 
it
lower bay. In order to evaluate the data-base (Table 7.8) is necessary to 
establish end members for organic reservoirs which are subject to mixing. 
The following values are consistent with generally accepted ones with the-
major uncertainty being the net phytoplankton: 
~
Cs terrestrial plants, e.g. elm -26 
~
Cs marsh plants, e.g. Juncus -26 
~
C 4 marsh plants, e.g. Spartina -13 
~
Seagrasses -10 
Blue-green algae -14
~ 
~
Net phytoplankton -20 
The model for Lavaca Bay is a simple one wherein more negative organic 
carbon derived from river transported C 3 plants and from marsh derived Juncus 
(also Cs) is mixing with phytoplankton to yield organisms, sedimentary carbon 
13 
and DOC with intermediate 8 C values. As has been pointed out seagrasses 
are absent from Lavaca Bay and Spartina is not very abundant. For the 
Matagorda Bay station seagrass must be taken into consideration. 
13 
A series of 6 C measurements were made on contents and muscle
gut 
tissue to establish the relationship between the tissue and the most recent 
feeding of each organism (Table 7.3). With only one exception, a flounder, the 
13 13 
animal tissue is between 1 and 3 per mil enriched in C (i.e. 8 C more 
positive) with respect to the gut contents. The muscle is a time integrated 
quantity while the gut content is short term. Nevertheless it appears that 
there is a small metabolic isotope effect for carbon. Other workers have made 
similar observations for other Based on this one can
ecosystems. argument 
13 
that 8 C values of animal tissue shown in Table 7.8 should be corrected
argue 
1 or 2 per mil to represent the food source. No such correction has been 
made, but the argument should be kept in mind. 
Marine sediments contain several types of organic matter including 
13 
macro-infauna which was removed. Thus 8 C determined on the remaining 
material provides data which should record a time integrated indicator of the 
13 
source of organic .matter. Irr Figure 7.1 8 C of all sediment samples are 
plotted against station number to test the simple model that the amount of 
river transported organic matter which is deposited in sediment decreases with 
distance from the river. There is clear trend which verifies the model;
a 
13 
station 623 does not fit the trend, being too heavy in 8 C. The ordering of 
the stations on the x-axis is somewhat arbitrary, but it does follow the 
13 
average salinity trend. The average 8 C values for sedimentary organic 
matter range between -22.5 and -17.5. This is not unexpected since even the 
river station has a plankton source for some fraction of its organic matter. 
The bay stations 1505, 1905 and 35/36 appear to have received very little river 
transported higher plant organic matter. Once again station 623 is more 
13 
positive, C enriched, than the trend would place it. 
13
• 
Infauna were picked from sediment, identified and subjected to 8 C 
determination. The same trend is seen for infauna (Figure 7.2) as for 
sediment; a strong higher plant/river signal near the river which grades into a 
13
• 
phytoplankton signal at the bay station. Infauna are ideal organisms for C 
tracer studies because they do not move substantial distances and thus make a 
13 
true record of 6 C of organic matter which comes their way. If -23 is taken 
13 
50
as the 8 C value which represents a 50 percent higher plant source and a 
percent plankton source then infauna from stations 45, 603 and 65 are mostly 
higher plant supported while the other stations are mostly plankton based. 
case.
Station 623 is again a special Bivalves, like infauna, non-mobile and
are 
13 13
. 
good 8 C recorders. Figure 7.3 shows a clear trend of 8 C with distance 
from the river mouth for bivalves. Bivalves are often used as indicators of 
pollution and they may be useful indicators of the source of organic carbon. 
Zooplankton are at the base of the food web and thus important to an 
understanding of the food web. The samples shown in Figure 7.4 represent 
hand picked zooplankton which are free of detritus. Each point represents 
more than one species, but the species are known and recorded in Table 7.8. 
Once again station 623 does not follow the trend. A strong input of river 
transported higher plant material is suggested by the fact that the Lavaca 
Bay/River stations (except 623) are more negative than -23.5. This observation 
confirms the suggestion that Spartina is not very important in this food-web 
13 
relative to Ca material. In order to more critically examine 8 C zooplankton, 
individual Acartia (100-200) were hand picked from selected collections and 
13 
submitted for 6 C analysis. The Acartia show the same trend with relation to 
station number (Fig. 7.5), as the mixed zooplankton but they have end members 
of -21.8 and -26.4 similar to our model. Acartia fall on the river source side 
of the mixing curve with an overall average of -24.0 ± 1.9. This supports the 
idea that zooplankton may be deriving substantial nutrition from higher plant 
detritus or from microorganisms that are consuming detritus. In other words 
in this estuarine system zooplankton are not just consuming phytoplankton, 
they are interacting with higher plant detritus. Crude net tows were also 
studied, but that data is not included in Figures 7.4 or 7.5. It is included in 
Table 7.8. 
Particulate organic carbon, POC, contains zooplankton, phytoplankton and 
13 
detritus. The 8 C values for POC in Fig. 7.6 do not correlate with station 
location very well, but it is interesting to note that most values are more 
negative than minus 23, indicating a strong river/Ca plant source; station 623 
again bucks the trend. Based on the fact that strong Ca and weak C 4 signals 
have been detected in Figures 7.1 to 7.5 it seems clear that the Bay POC 
values of -20.3 represents marine plankton and not a mixture of C 3 and 
CVseagrass; open bay stations less negative than -20 may represent a seagrass 
influence. Dissolved organic carbon, DOC, shows little relation to station and 
only a modest river signal (Fig. 7.7). DOC is too complex to yield to a simple 
model. 
The fish samples were taken with the net used in the distribution and 
13 
abundance study, which catches fish of a few cm length. The plot of 8 C of 
all fish vs station number (Fig. 7.8) shows a fairly strong correlation, 
13 
especially if station 623 is ignored. The average 6 C values of all fish, 
sorted by station range between -21.5 and -19.0, a range which in Figure 7.8, 
is suggestive of plankton as a source of carbon. Since fish are more
one or 
steps up the trophic scale the small metabolic effect described in Table 7.3 is 
probably shifting them 1.0 or 1.5 per mil in the plus direction relative to their 
food. At this time it is not appropriate to make a correction based on this 
but one should be aware of the idea. Not all individual fish fall in this 
13 
narrow Table 7.4 shows the 6 C value of the same 198 fish
range. average 
sorted according to type wherein the range is -17.1 to -24.6. The average 
13 
S C value of all fish used in the study is -20.6 ± 2.6. Individual species do 
not correlate with station as well as all species do, as shown in Figure 7.9. 
I3 
£ Fundulus
Specialized feeding patterns for Cyprinodon (avg. C = -17.3), and 
13 
(avg. 6 C = -17.6) are evident. 
Shrimp are like fish in being mobile and thus more able to seek food. 
13 
all
The plot of 8 C of penaeid shrimp (Fig. 7.10) shows a fairly strong 
13 
correlation with station. The average 6 C values of all Lavaca Bay samples 
are more positive than -23 suggesting a mixed higher plant and plankton food 
source. The shrimp value at the Bay station (-17.4) compares with offshore 
Gulf shrimp (-16.5)-(Fry, 1981)'. However it is possible that both samples may 
taken beds
have been slightly influenced by seagrass. Shrimp from seagrass in’ 
13 
the Laguna Madre have 8 C values in the -12 to -13 range (Fry and Sherr, 
13 
1984). Table 7.5 shows 8 C of shrimp as a function of station and month. 
July collections at the river stations stand-out, but the data is inadequate to 
13 
make a firm conclusion. The same trend is seen for 8 C of fish vs station 
and time of collection (Table 7.6). 
15 
A suite of samples was selected for the determination of 8 N. These 
13 
samples were subsamples of freeze-dried and powdered material for which 8 C 
15 
had been determined. 8 N is generally viewed as a tracer of the source
not 
of organic matter, i.e. terrestrial plant vs phytoplankton. It is rather an 
indicator of the level of an organism on the trophic food scale. The samples 
for 515 N were selected to span the trophic structure of the river/bay 
ecosystem. Table 7.7 illustrates this trophic relationship in a gross way. 
Higher plants and macroalgae are at the less positive end of the Table. The 
IS 
trophic shift of £ N, mentioned earlier, of 2 to 4 per mil is evident in Table 
7.7 with infauna as a being the most positive. This does not indicate
group 
that infauna are at the top of the food-web, because no doubt several food-
webs are represented in the data. However it does indicate that infauna, fish 
and shrimp are fairly near the top. Among fish, croaker at +l3 to +l4 are 
higher than Cyprinodon at +7. In another study large redfish were +l7, clearly 
15 
a top carnivore. Station number was not expected to correlate with 5 N, 
however based on Fig, 7.11 that expectation is reconsidered. Figure 7.11 
15 
shows a weak trend for 8 N to become more positive with distance from the 
+2
river. If higher plant organic nitrogen is to +3, while phytoplankton 
15 
nitrogen is +5 to +7, then a weak station to 8 N relationship might be 
9 
15 
superimposed over the stronger trophic nitrogen pattern. While the 8 N 
-
relationships are interesting, at this time the data base is too small to 
13 
completely resolve specific food-webs. Almost all of the samples used for 8 C 
1$ 
are achieved as a dry powder which could be used for future 5 N studies. 
CONCLUSIONS 
13 
The 8 C data combined with a simple, conceptual mixing model indicate 
that marsh
substantial river transported higher plant, C 3 and C 4 plant organic 
carbon is being taken up and assimilated by organisms in the Lavaca Bay 
ecosystem. The degree of assimilation correlated with distance from the river 
for sedimentary organic matter and for a number of biota. The utilization of 
river transported organic matter is most intense in bivalves and surprisingly in 
zooplankton, Acartia. Shrimp and infauna show the river signal but less so 
than bivalves and Acartia. Fish show the least utilization of river transported, 
Cs-higher plants. This is taken to indicate a plankton rich diet because the 
role the be
of sparse Spartina stands do not appear to generally significant. 
13 
The generalizations, based on 8 C data, combine with abundance data for the 
various species indicate that river and its associated marsh is important in the 
food-webs of the estuarine A similar, but much less extensive, one
system. 
13 
of al
year survey 8 C of samples from the study area (Ward et 1982) found 
trends like those discussed. Taken together the two years of data of this 
study and the one year survey are a sound argument for the importance of 
freshwater for the Lavaca Bay system. 
LITERATURE CITED 
13 12 
Anderson, R.K., A.L. Lawrence and P.L. Parker. (1987). A C/ C tracer 
study of the utilization of presented feed by a commercially important 
shrimp, Penaeus vannamei in a pond growout system. J. World 
, 
Aquaculture Society. 18(1). 
DeNiro, M.J. and S. Epstein. (1978). Influence of diet on the distribution of 
carbon isotopes in animals. Geochimica et Cosmochimica Acta. 42:495­
506. 
13 
Fry, B and E.B, Sherr. (1984). 6 C measurements as indicators of carbon flow 
in marine and freshwater ecosystems. Contribution in Marine Science. 
27:13-47. 
Fry, 8., A. Joern and P.L. Parker. (1978). Grasshopper food web analysis: use 
of carbon isotope ratios to examine feeding relationships terrestrial
among 
herbivores. Ecology. 59:498-506. 
Van Der Merwe, N.J. (1982). Carbon isotopes, photosynthesis and archaeology. 
American Scientist. 70:596-606. 
Ward, G.H., Jr., N.E. Armstrong and J.M. Wiersema. (1982). Studies of the 
effects of freshwater inflows into Matagorda Bay, Texas. Phase 3 final 
TX: Huston &
report. Austin, Espey, Associates and the University of 
Texas at Austin; prepared for U.S. Fish and Wildlife Service, Division of 
Ecological Services, Albuquerque, N.M. 1 vol. 
FIGURE 7.1 
_
Figure 7.1 Data 
FIGURE 7.2 
-
FIGURE 7.2 DATA 
FIGURE 7.3 
-
7.3
FIGURE DATA 
¦ FIGURE 7.4 
Data
Figure 7.4­
Station(s) Average Std. Dev. Number 
45 -25.7 0.79 7 603 -24.9 1.12 7 65 
623 -21.7 1.98 3 613 -23.8 1 633 -25.1 1.12 3 85 -23.8 1.88 8 
Bay -22.0 0.99 16 
All -23.5 1.97 45 
FIGURE 7.5 
Figure 7.5~ Data 
Station(s) Std. Dev. Number
Average 
45 -26.4 0.30 3 603 -24.4 1.26 4 65 623 -22.5 1 613 -23.8 1 633 -25.9 0.08 2 85 -24.9 
Bay--21.8 0.92 6 
All -24.0 1.90 20 
FIGURE 7.6 
-
FIGURE 7.6 DATA 
FIGURE 7.7 
-
FIGURE 7.7 DATA 
Dev.
Station(s) Average Std. (N) 
45 -23.4 0.80 4 603 -22.5 0.04 2 65 -23.0 0.69 3 623 -19.4 1.57 3 613 -22.4 1.87 4 633 -19.0 1 85 -21.7 1.35 4 
BAY -22.8 1.77 8 
ALL -22.2 1.89 29 
FIGURE 7.8 
FIGURE  7.8  - DATA  
Station(s)  Average  Std.  Dev.  Number  
45  -21.45  2.79  36  
603  -21.09  2.35  39  
65  -20.24  2.86  24  
623  -19.12  2.86  24  
613  -20.66  2.54  20  
633  -20.65  2.08  13  
85  -20.50  1.80  37  
BAY  -19.01  1.22  5  
ALL  -20.58  2.57  198  

FIGURE 7.9 
Data
Figure 7.9­
Del 13-C Croaker 
Station(s) Average Std. Dev Number 
45 -22.3 1.63 6 603 -22.4 1.60 
7 
7 623 -20.0 1.97 5 613 -21.5 1.35 5 633 -19.9 
65 -22.9 1.42 
2.04 4 85 -21.9 1.16 12 
-21.9 1.16 12
Bay 
All -21.6 1.88 50 
Del 13-C Anchovy 
Station(s) Average Std. Dev Number 
6
45 -22.0 1.21 
6
603 -21.7 1.05 
65 -22.7 0.28 3 623 
-21.4 0.23 2 
-22.6 2.33 3 633 -21.8 0.88 3 85 -21.1 1.18 5 
613 
Bay -18.5 0.04 2 
All -21.6 1.53 30 
FIGURE 7.10 
FIGURE  7.10  - DATA  
Station(s)  Average  Std.  Dev.  Number  
45  -22.1  2.07  8  
603  -23.0  1.18  9  
65  -21.4  0.34  3  
623  -19.5  1  
613  -20.2  1.22  14  
633  -22.3  0.02  2  
85  -21.6  1.49  10  
BAY  -17.4  1.28  3  
ALL  -21.4  2.02  50  

FIGURE 7.11 
FIGURE  7.11  -DATA  
Station(s)  Average  Std.  Dev.  Number  
45  9.10  2.82  3  
603  12.80  0.67  3  
65  0  
623  0  
613  0  
633  0  
85  12.23  2.25  6  
BAY  14.58  0,00  1  
ALL  11.82  2.62  13  

TABLE 7.1 
13 
6 C of Organisms Taken In the Same Trawl 
Sta. 613 Sta. 85 
Individual w. shrimp croaker 1 -21.39 (2)* -22.46 (2.1) 2 -18.98 (2.5) -23.24 (2.5) 3 -19.16 (3) -23.18 (2.7) 4 -22.32 (3) -23.13 (3.3) 5 -18.42 (3) -22.28 (3.3) 6 -18.55 (3.5) -22.52 (3.8) 7 -19.12 (3.5) -22.27 (4.5) 8 -20.43 (61 -20.10 (4.8) 
x ± s.d. -19.71 ± 1.52 -22.4 ±1.01 
* length in cm 
TABLE  7.2  
SAMPLING  SCHEDULE  
ISOTOPE  STUDY  
Station  
Date  45  603  65  613  623  85  633  1505  1905  35/36  
27-29  +  +  -f  +  +  +  +  
Nov.  1984  
22-24  +  +  -f  +  +  +  
Jan.  1985  
2-3  +  +  +  +  +  +  +  + s  + s  
Apr.  1985  
16-17  +  +  +  +  +  +  +  
Jul.  1985  
22-24  +  +  +°  +  +  +  +  +  
Oct.  1985  
4-5  +  +  +  +  +  O­ +  
Feb.  1986  
8-10  +  +  + POC  +  +  +  +  -f  
Apr.  1986  
s  =  sediment only  
POC  =  water column  POC  only  
o  =  oysters only  

Table 7.3.  Comparison  of 6 13 C  values  for muscle  tissue and  gut  
contents of  some  samples- 
Size  
Species  JL  (cm)  Muscle  Gut  Station  Date  
White  shrimp  8  5  -24.3  •-27.2  45  7/85  
Mullet  2  5  -19.2  -19.3  45  7/85  
Menhaden  4  3.5  -24.6  -25.7  45  7/85  
Blue  catfish  2  9  -25.7  -27.0  45  7/85  
Anchovy  12  2.5  -24.0  -26.4  45  7/85  
Anchovy Sea trout  6 1  2.5 6  -23.9 -21.3  -25.7a -22.0  603 603  7/85 9/85  
Blue  catfish  2  11  -24.7  -24.9  603  9/85  
Croaker  4  7  -24.2  -26.4  603  7/85  
Flounder  1  14  -21.3  -20.4  603  4/85  
Flounder  4  7-5  -24.7  -26.0  603  7/85  
Menhaden  2  4.5  -24.1  -24.5  603  7/85  
Menidia  3  3.5  -23.5  -23.7  603  7/85  
Mullet  2  7  -21.6  -22.7  603  7/85  
Brown  shrimp  6  6  -23.3  -25.3  603  7/85  
White  shrimp  7  7.5  -23.2  -24.3  603  7/85  
Croaker  3  5  -20.1  -23.2  65  4/85  
Menhaden  8  2.5  -21.0  -26.2  65  4/85  
Mullet  1  4  -17.5  -21.2  65  4/85  
Rangia  1  -24.0  -26.3  ..  613  11/84  
Menhaden  8  2.5  -20.8  -23.1  613  4/85  
Anchovy  7  4  -20.7  -21.5  613  4/85  
Flounder  4  3  -20.4  -23.2  613  4/85  
Croaker  8  3  -21.0  -22.3  613  4/85  
Macoma  1  -23.6  -23.9  633  8/85  
Mullet  2  2.3  -19.6  -20.5  633  4/85  
Anchovy  3  3  -22.6  -25.7  633  7/85  
Paleomonetes  8  2.5  -18.2  -19.3b  623  4/85  
Anchovy  6  4.5  -22.9  -24.8  85  7/85  
Anchovy  9  2.2  -21.3  -21.9.  85  4/85  
Croaker  6  3.5  -20.7  -22.0  85  4/85  
Croaker  1  6  -19.6  -21.0  85  4/85  
Fundulus  1  6  -11 .1  -19.4  •  •  85  4/85  
Hardhead catfish  1  12  -20.2  -22.2  85  7/85  
Menhaden  7  2.5  -19.1  -20.6  85  4/85  
Sea  trout  1  4  -21.6  -23.2  85  7/85  
Tonguefish  1  7.5  -20.9  -22.6  85  7/85  

2 
Species  |_  Size (cm)  Muscle  Gut  Station  Date  
Oyster Brown shrimp Macrobranchium Paleomonetes White shrimp  2 5 1 6 5  4.5 3 3 7.5  -23.2 -22.2 -19.1 -19.3 -22.5  -25.5C -22.3 -21.6a -19.9 -23.4  85 85 85 85 85  4/85 7/85 7/85 7/85 7/85  
Oyster  2  -20.3  -23.4a  1905  11/84  
a k c  Whole animal. Eggs only. Fat only.  

TABLE 7 4 

Del I3—C f-is 11 
I>eI 13-CofSelectedFjsh Specjes 
Spec ie'3 Averaqe S td.Dev. I'iunil »er 
Ao.ciio vy  -31 .6  1  .53  30  
Calf:sh  -29  i  1.69  9  
.  
Croa'Ket  -2 I  6  I  9G  50  
.  .  
i'ypr i 1:0 don  -1  7.3  1  .  C‘i  1 9  
i r  1 ounder  -21  8  2.59  5  
.  
F 11 nd j j I t is  -17.6  I .  79  29  
Menhaden  -21.3  i  92  29  
.  
Hen i < i  i o  -20.3  L  . 65  i  9  
r*i* t j i e t.  — i G . 8  I . 09  1 9  
Sp-z-c. k i ed  Trout  -21.1  0.62  3  

0 thers -22.0 2.78 O 
I J •20 6 2.57 tOG 
-
TABLE  7.5  
- '  
l'-e i  1 3—LI  Shr i nip  
j  .* (. ; •;: , 6 *'i 6o:j 65 623 A 3 '3  IAN -20 -1 ¦ 2< f . 0 -20. 0 -1 B . 5 • 20. •  I-lr i3 -21 .7 22. B  Mnnt.li APR -28.0 -20.3 -22.0 -19.9 — 19. «  -26 . J -23 -9  DC 1 -2 ¦ . 3 -2 : -7  NOV -20.6 -20.2 -20.6 -19.6 -20.2  A I i -22.2 -22. I -2 2 .2 -19.6 -20.2  ( N ) 1 5.0 15.0 9.0 6.0 3 5.0  c. _ rj 1 .96 1 . 99 2.06 i . 36 1.18  
633 05  -1 .‘3 .  S  -cl -8 -a ¦ . a  ”2 i .3 -2 I .5  -21 .7 -2 1-9  -03  '3  -20.3  -2 • — 2 i  . 6 .2  6.0 19.0  2. 1 2 1.79  
R  = y  - 1 7 .  w  -17.3  -17.6  3.0  1  .23  
A1 1 •: N > s . d - _ p'~) p 7 . 0 2 . 00  -Pi . Q 6 . 0 O . 56  _-J i *3 20 -0 2-5m  -23.0 18.0 1 .69  — 2 . 3 i 3.0 I . 00  -20. 1 23.0 J . 35  -21.2 90.0 2.32  90  2.32  

TABLE  7.6  
Del  13-1  P i  «-ih  
.  
j I .? (  i r<n { s  M011I.I1  
JAM  APR  JUL  nr:i  HOv  m’i I  ( M )  . d.  
m 5  -­F;< ). 65  -7? 1.13  -23.35  -20.59  -20.25  -21  . '*5  36  Zi  '7 0  
D 1  -10.93  -21.06  -23.02  -21.39  20.39  -21.09  39  r? . 35  
65  20 . GO  -20.QI  -19.09  — pij. pM  2m  ;? . 86  
23  -13. .39  -19.59  -19.S6  -19.12  P-'i  cl  GO  
.  
6 ! 3  -01.79  -20.33  -20.35  -20.90  -20-66  20  C“ t|  
633  -20.3G  -21.09  -20.91  -20.65  ; 7  cl  09  
.  
S3  -19.20  -1 9.53  -21.11  —19.97  -21 .‘V7  -20.50  37  1  so  
.  
Qa » ••  -JO.08  -20.91  -19.01  5  1  n -> . czc  
A 1  j  -19 - 02  -20.35  -22.83  -20.15  -20.3"  -20.5G  1 9P.  a. . 57  
( i i ;  M 3  53  26  1 3  O J  1 99  
S . r i .  p _ <--.9  1 . G3  2 .92  5 . 27  2.82  —• r*'' C . /  

TABLE 7.7 
5 IS 
N BY SAMPLE TYPE 
6 lsN 
Infauna  + 11.9 ±  2.6  
Fish  11.6  ±  2.5  
Oyster  11.4 ±  1.1  
Shrimp  11.1 ±  1.1  
Zooplankton  (Acartia)  10.1 ±  0.5  
Crab  10.0 ±  1.1  
Bivalve  (Rangia)  8.5  -­ 
Bivalve  (Mulinia)  8.1 ±  0.2  
Amphipods  7.6  -­ 
Detritus  5.9  ±  0.9  
Sediment  5.4  ±  5.4  
Plants  4.7 ±  1.9  

7.41
del-N15 11.5 
c:S 1X
3 26 i,9J9 8.8 5J9J J 9J 
•. • 
» a.% .. * 
VX 9JU7/ y 0v
21
-19 -22 -20.0 -18.5 -18.1 -20.1 -21, -20.6 -21. -19 -20.5 -18 -20 -21.4 -19 -18.8 -22.0 -22.4-19.8 -18.5 -17.8 -15.9 -18.1 -24.3 -22.6 -22.8 -21.9 -21.2 -21.4 -21.6 -22.7 -23.9 -25.1 
4* X 1XX1•L X 2X
de1-C1 
part 
tail guts tail muscle
Body 
cm 
5cm 2cm 
.. 
65
Size 4 
31 25 
11 

10 55
150 150 125 150 125 150 
7.8 
DOC DOC POC POC
delta tinea sp. delta fil. tonsa tonsa tonsa 
TAI3LI3 Organism lateralis mitchilli mithilli capitata Maldanidae calif. Dorvilleidae Glycera limicola Eudorella Spionidae Armandia HaploscoloplosParonidae americana Ogyrides sediment sediment aztecus brevis nauplii-a nauplii-b Paracalanus Petrolisthes Chaetognatha DOC-RepA DOC-RepB 
C. A.A.
Nemer 
A. 
Cossura Acartia
G.
Mulinia Anchoa Glycera Mediomastus Ogyrides Heteromastus Penaeus Loligunculus Barnacle Barnacle 
Type 
Sample bivalve DOC DOC fish fish infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna POC POC sediment sediment shrimp squid zoopl zoopl zoopl zoopl zoopl zoopl zoopl zoopl 
DOC DOC Apr Apr Mar Oct Oct Apr Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Oct Oct Oct Oct Oct Oct Apr Mar Apr Jun Oct Oct Feb Feb Feb Oct Oct Oct Oct Oct Dec Dec 
Date 1986 1985 1985 1985 1985 1986 1986 1986 1986 1986 1986 1986 1986 1986 T9 1986 1985 1985 1985 1985 1985 1985 1985 1985 1985 1986 1985 1985 1986 1986 1986 1985 1985 1985 1985 1985 
Station 86 1505+19051985 1505+19051985
555555555 5 5 55 5555 
00000 0 00 0
1505 1505 1505 1505 15 15 15 150 15 1505 15 1505 150 150 1505 150 1505 1505 15 1505 1505 1505 1505 1505 1505 1505 150 1505 1505 15 15 1505 150 150 150 15 
7.42 
2X6 7 
9 
8U 1 
5 14uX 11. 13.2 10.6
del-Nl 
" 
6VJ 2 *1 .4*7156V6V 4H 7 2X5-J 6v 5nj7/ 
•
• . .••• • %t• •• 
9X W
V W .. UvJX0 v .X
20 19 20 20 1921
-21.8 -18.5 -18.5 -21.8 -18.4 -22.6 -23.7 -20.0 -20/6 -4 -20.6 -19.1 -18 -20.8 -21.8 -19/ -20.0 -16.8 -21.3 -20.2 -18.9 -20.5 -21.9 -18.7 -22.9 -19.6 -20.4 
X X X1XXX X XX2X X XX
-20 -18 -21 -21
del-013 
, 
part 
muscle tail tail tail
Body 3cm 5cm 5cm 
<. . 
34
Size * 
1 455 
II 

POO POO DOC DOC DOC sp.
POC-b POC-a und. magna Nereis delta delta
lateralis sapidus undulatus mitchelli Nereis capitata Nemertinea Ogyrides Magelona Nemertinea Maldanidae americana Mediomastus Paronidae Drilonereis Nemertinea Paronidae americana setigera limicola Drilonereis
0. C.
Organism Callinectes Micropogonias Drilonereis Phyllodocidae HaploscoloplosDorvilleidae Spirochaetopterus Glycera Ogyrides californiensis
M. M.A. G. 
G. Tharyx 
M. 
Type 
Sample bivalve infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna

POO POO POO POO crab DOC DOC DOC fish fish fish Dec Feb Feb Oct Feb Nov Apr Aug Mar Nov Nov Oct Apr Apr Apr Aug Aug Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Oct Oct Oct Oct Oct Oct Oct Oct Oct 
Date 1986 1984 1985 1985 1985 1984 1984 1985 1986 1986 1986 1985 1985 1986 1986 1986 1986 1986 1986 1986 1986 1986 1986 1986 1986 1985 1985 1985 1985 1985 1985 1985 1985 1985 
Station 1505+19051985 1505+19051986 1505+19051986 1505+19051985 
1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 
25 8W 
w 9.
11. 11. 5'.• ;I
del-N15 9J 
3 9 9J JL 593J5 X x6V5 8U2X53J1X c:X *7 5J 
del-013 • •.( •#•t ••i ...
% 
J OU
J X V >Jv vjV U7O
19 r18
-20,3 -23.4 -25. -22.4 -19.8 -18.8 -17.2 -18.1 -17*3 -17, -22.2 -22.1 -22.2 -20.5 -23.0 --24.4^ -17.3 -22.1 -20.3 -18 -17. -20 -19. -19.2 -19.1 -18 -20 -19.9 -18 -20 -18. -18 -19 / --17.2
X X XxXX XX XXX1XX
M1 -X 
part 
muscle whole tail muscle tail
Body 
7cm 4cm 
.
large 
-
3
Size 
2245 2 
II 

150 47 160 200 
tow POC POO 

tonsa
virg. brevis nauplii DOC Nereis abdita Nereis cuprae
Net 
Organism virginica sediment sediment sediment setiferus Chaetognatha CtenophoraParacalanus lateralis undulatus Nemertinea Phyllodocidae Ogyrides Nereidae Diopatra Maldanidae Nemertinea Drilonereis Mediomastus Magelona Glycera Cossura Clymenella monodon phyllisae Ogyrides 

C. P. M.M.
Crassostrea L. Barnacle A. Eudorella Ampelisca Diopatra
Magelona 
Type 
Sample bivalve bivalve plankton sediment sediment sediment shrimp squid zoopl zoopl zoopl zoopl zooplbivalve infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna
POO POO DOC fish Nov Nov Nov Apr Mar Apr Feb Jun Nov Oct Feb Oct Oct Oct Oct Feb Dec Oct Aug Aug Aug Aug Feb Feb Feb Feb Feb Feb Feb Feb Feb Oct Oct Oct Oct Oct Oct Oct Date 1984 1984 1984 1985 1985 1985 1986 1986 1984 1985 1986 1985 1985 1985 1985 1986 1985 1985 1985 1985 1985 1985 1986 1986 1986 1986 1986 1986 1986 1986 1986 1985 1985 1985 1985 1985 1985 1985 
5
Station 1905 1905 1905 1905 1905 1905 1905 1905 1905 1905 '190 1905 1905 1905 1905 35/36 35/36 35/36 5/36 35/36 35/36 5/36 5/36 35/36 5/36 5/36 5/36 35/36 5/36 35/36 35/36 35/36 5/36 35/36 5/36 5/36 35/36 5/36 
3 333333 3
3 33 
9.4 6.3 7.44
del-N15 
' 
0v7 a6w 
.% 
96 X
21
-18.2 -18.2 -19.0 -17.1 -15.7 -20.9 -20.3 -17.9 -19.9 -19.0 -11.7 -21.0 -20. -27.1 -21.8 -20.0 -19.9 -20.5 -25.2 -22.8 -26.7 -26.5 -24.1 -22.6 -22.6 -21.9 -21.4 -19.6 -22.3 -21.1 -19.7 -.22.1 -18.1 -21.0 
1 C*
1X
del-C13 
part tail muscle claw body body claw tail tail tail tail tail tail tail backbone tail
Body 
•
5cm 5cm 5cm 4cm 5cm 4cm 
.. 
6-7cm large small large l-3cm 3-4cm 2-3cm
.-­
-
7 7 3343
Size 
3 111 149368 
II 

1 602 11 10
150 100 155 2 POC POC DOC DOC DOC sp.
Drilonereis americana culveri verrilli Apreades rep.l rep. Sediment sediment aztecus brevis tonsa tonsa Chaetognatha Paracalanus lateralis sapidus sapidus sapidus sapidus detritus detritus detritus detritus undulatus cephalus patronus Menidia undulatus mitchilli cephalus undulatus
A. A. 
P. C.C.C.C.
Organism Ictalurus
G. 
M. M. M.A. M.
Noctiluca Noctiluca L. Trawl Trawl Trawl Trawl Mugil
Laeonereis Ampelisca Brevortia M. 
Type Sample infauna infauna infauna infauna infauna plant plant POC POC sediment sediment shrimp squid zoopl zoopl zoopl zoopl bivalve crab crab crab crab plant plant plant plant DOC DOC DOC fish fish fish fish fish fish fish fish fish 
Oct Oct Oct Oct Oct Feb Feb Dec Feb AprFeb Oct Oct Feb Oct Oct Oct Apr Apr Nov Nov Nov Apr Jan Nov Oct Apr Jan Mar Apr Apr Apr Apr Apr Apr Apr Jan Jan 
5
Date 1985 1985 1985 1985 1985 1986 1986 1985 1986 1985 1986 1985 1985 1986 19-8 1985 1985 1986 1985 1984 1984 1984 1985 1985 1984 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 
6
Station 35/36 5/36 5/36 5/36 5/36 5/36 5/36 5/36 35/36 35/36 35/36 5/36 5/36 5/36 35/3 5/36 5/36 5 P555 5 55r5555 3 A4
333333 33333445 A44545P4AC44544545 4545 a4 444545 
44 
3w 9
•/ 7.45 
.I •. 
/
7 6v
del-Nl'5 13.1 
-
2 2 7 4 5 844*1607/ A
3 01 16 
, . ..f» % 
V 0v 1JL Q
-16. -24.1 -18. -19. -20.4 -14. -17. -21.8 -19.4 -22.7 -22 -19.3 -27.0 -19 -24,6^”21,1 -26.8 -25.7 -25. -24.5 -26.4 -28.3 -24.1 -23.3 -22.8 -20. -22.4 -16.0 -17. -22.3 -16.6 -23 -17 -20 -20.7
w 26 2ft9 
_
del-C13 
part 
skin tail muscle whole liver scales tail tail tail whole tail guts gutstail tail tail tail guts tail tail guts tail tail tail tail tail tail tail tail tail tail tail tail tail tail
Body 

. 
cm
3cm 2cm 2cm 2cm 3cm 5cm 5cm 4cm 3cm 7cm 5cm 4cm 4cm 5cm 6cm 5cm 8cm 7cm 
Size 13cm 20cm 13cm 13 2-3cm -9-10cm 2-3cm small large small large
. . ...
2-> 
4 33 2 31.3 
2 522411 1811 6
5224421 1 181
10 1010 12121010 2010
II 
sp. sp. sp. sp. sp. sp.
felis 
larvae
cephalus cephalus cephalus cephalus cephalus varie. patronus patronus similis cephalus cephalus patronus patronus undulatus mitchilli maculatus mitchilli patronis undulatus mitchilli similis variegatus mitchilli similis undulatus variegatus mitchilli mitchilli Myrophis culveri 
A. 
F. F. 
M. M.M.M.M. B. B. M. M.B. B. B.
Organism Menidia Ictalurus Menidia Ictalurus Ictalurus Menidia 
M.A. A. M. A. A. M. A.A. 
0. C.
Cyprinodon Fundulus Chironomid Laeonereis
Trinectes 
•
Type Sample fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish infauna infauna infauna 
Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Oct Oct Apr Apr Apr 
4 
8
Date 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1984 1984 1984 1984 198 1984 194 1984 1984 1984 1985 1985 1985 1985 1986 
Station 
5555555 5 5 C
555 5 55 55555r5555
C
4545 4,5 45 4545 4545 45 454545 45 45
4444444 44 4 a
4 4 44 44A44A 44
'4 444 
9 
. 
L, X 
6.4 5.8 5 12J 12,1
5
del-N15 * 7.46 
3 7286 C fJ 9 4*11X X 6U 
1• t 
'J TX V1v
-26, -23. -21. -23.9 -24 -27.5 -22.1 -26.7 -24.3 -21 -25.5 -12.1 -25.5 -27 -19.2-24.1 -20.6 -25,4 -24 -21.9 -23.3 -21.6 -22.1 -21,4 -19.8 -24.3 -21.7 -20.1 -21.8 -24.3 -23.3 -27.3 -23.7 -20.0 -.21.2 -20 -21.8
fcC «w 
w 
-
del-Cl. • 21 I i 
. 
part 
tailtailtail tailtailtailtail gutstailtailtailtailtail
Body 5cm 4cm 6cm 5cm 2cm 2cm 6cm
l-3cm 4-6cm 5-8cm
,.
-
0.1. 1.
83 2
Size 
3549 18384 834 
It 1010 
POC POC POC POC
larvae Nemertinea capitata Hobsonia Edotea CorophiumLaeonereis larvaeLaeonereis larvaeromqrianus 'patens australis frutescens stick stick algae sediment sediment sediment setiferus Mysidae setiferus sp. setiferus setiferus aztecus aztecus 
off off
Organism Palaemonetes Macrobranchium Palaemonetes Palaemonetes Penaeus Macrobranchium Palaemonetes 
P. P. 
P. P.P. P.
Chironomid Capitella Chironomid Chironomid Juncus SpartinaPhragmites Iva Algae AlgaeBlue-green 
Type 
Sample infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna plant plant plant plant plant plant plant sediment sediment sediment shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp
POC POC POC POC 
Apr Apr Apr Feb Feb Feb Feb Feb Oct Oct Jan Jan Jan Jan Jul Oct Oct Apr Dec Jan Mar Apr Feb Jun Oct Apr Apr Feb Jan Jul Jul Jul Jul Jul Nov Nov Oct Oct 

Date 1986 1985 1986 1986 1986 1986 1986 1986 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1986 1986 1985 1985 1985 1986 1985 1985 1985 1985 1985 1985 1984 1984 1985 1985 
Station 
5 5555555555 
55 555555555555
4554 454545 4 44454 45445445 45454 454544 444444 4
444 4 444 44 
del-N15 5.3 13.8 7.47 
3 1 9546053 2 7 4n
.'3 7.1 / 
17/ v
-21.6. -26.0 -24.9 -24.7 -26. -24.7 -26.8 -26.3 -26.3 -24 -21.2 -18.9 -17.0 -16.8 -26.5 -25.6 -22.6 -22.5 -20.3 -21. -19. -21. -21, -22. -20. -18. -19 -17. -24.5 -21.3 -20.4 -24 -21.6 -21.8 --18.8 -16 -19.3
Xx
de1-C1 .• • 
part 
tail claw claw whole muscle tail tail skin tail tail tail tail tail tail tail tail tail guts tail liver tail tail tail tail tailBody 
cm cmcm
5cm 5cm 4cm 5cm 5cm 5cm 2cm 2cm 5cm 5cm 2cm 5cm 3cm 3cm
small 2-3cm 14cm 14cm 10cm 14cm
57 14
.. . 
. >­
Size 4 435. 2.4 2-1 
3 5 1221 29227291 2 5
1 1 11113
59 17 
10 10
II 
160 115 150 
POC DOC DOC DOC sp. sp.
zooea tonsa tonsa tonsa
aztecus Diaptomus medusae Argulus sapidus sapidus sapidus sapidus detritus detritus Fundulus undulatus lethostigma mitchilli undulatus undulatus Fundulus patronus Cyprinodon maculatus lethostigma lethostigma lethostigma patronus Fundulus cephalus Cyprinodon undulatus

A. A.A. 
P. C.C.C.C. 
B. B.M.
Organism Menidia Ictalurus
M. A.M.M. T. M.
Xanthidae Scyphozoa Trawl Trawl 
P. P.P. P. 
Type 
Sample shrimp zoopl zoopl zoopl zoopl zoopl zoopl zoopl POC DOC crab crab crab crab plant plant DOC DOC fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish 
OctAprAprFebFeb Oct OctOctOctAugAprJanNov NovJanNovAprJanAprAprAprAprAprAprAprAprAprAprAprAprAprAprAprJanJanJanJan Jan Date 1985 1985 1985 1986 1986 1985 1985 1985 1985 1985 1985 1984 85
1985 1984 19 1984 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 
Station 45+603 45/65 603
5 
0
4545 4545454545 603603 603 603603603603603603603603603603603603603603603603 6036036036036033603603
4 
6 
54 
7.48 
12 12.3 10.8
del-Nl . 
< 
3043 22 
-19.5 -26.4 -23.5 -24.9 -23.9 -24.2 -24.7 -26.0 -23.7 -24.7 -25.7 -22.7 -24.1 -21.6--24.5 -18.2' -20.8 -24 -17. -17 -20.8 -20.2 -23.1 -23 -18.9 -21.3 -21.0 -22.0 -21. -23.5 -24 -23.0 -26.7 -25.0 -25.1 -23.7 -25.5 -22.3
del-C13 . .. . 
part 
trout
tail gutstailgutstailtailtail gutsgutstail gutsgutstailtail gutstailtailtailtailtailtailtailtailtailtail muscletail tailBody 
ex 
2cm 5cm 3cm 7cm 5cm 7cm 5cm 2cm 8cm 4cm 2cm 3cm 4cm 3cm 5cm 6cm 2cm 5cm 4cm
11cm 
. . ....
7-8cm
-
,2 
232 42 3
Size » 
44326444326222231115321111316 1 
II 
sp. sp. sp. sp. sp. sp, 
(rep) larvae
Fundulus undulatus mitchilli undulatus lethostigma lethostigma mitchilli cephalus patronus cephalus patronus Cyprinodon undulatus Fundulus Fundulus mitchilli Fundulus patronus ..undulatus nebulosus mitchilli mitchilli mitchilli Nemertinea larvae-a Corophium larvae-b Streblospio Nemertinea Backswimmer

Organism Menidia Ictalurus Menidia Ictalurus Menidia Menidia 
M. B.M.B. B. 
M. A.M. A. M. A. M. A.A.A. 
Nemertinea Chironomid
P. P. 
Cynoscion Chironomid Chironomid 
Type 
Sample fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish infauna infauna infauna infauna infauna infauna infauna infauna insect 
Jan Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Oct Oct Oct Oct Feb Feb Feb Feb Feb Oct Oct Oct Apr 
Date 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1984 1984 1984 1984 1984 1984 1984 1984 1984 1984 1985 1985 1985 1985 1986 1986 1986 1986 1986 1985 1985 1985 1985 
333 3
Station 
00 
0
603603603603 6036036036036036036066603603603606036036036036036036036033603603603603603603603603603603603603 
6 
. 
7.49 
4 
3.8 7 10.2 10.2 9.7 11.7
del-N15 
3 52X ’9 31X3 -J3J50v 0V 0v I 
1•%•t %*• % 
4T Vy5J J X6w 4H
-24.0 -22.1 -31. -20,5 -24.3 -24.2 -26.8 -26.1 -21. -21.8 -21.5 -21.1 -20 -22.8 -19 -24.9 -23.2 -23.3 -23.2 -22 -19.0 -21.3 -22 -21.9 -24.9 -22.9 -24.9 -25.4 -23.8 -26.2 7 -24.4 -25.1 
2X xX X26 X X2X2x
-24 -19 
• 
-
de1-C1 
part 
• 
tail tail whole guts tail tail guts tail tail tail chitin tail tail tail whole 
Body 
3cm 5cm 9cm 5cm 4cm 1cm
-8cm -7cm 
3-5cm
. 
• 
0 76
Size . 
2667 433
11 
9766 517 1
10 1010 5990
II 
100 110 100 200 
tow POC POC POC
POC-a POC-b zooea tonsa tonsa 
Net
Detritus Cladophora Cladophora Marsalia sediment sediment sediment Mysidae Mysidae setiferus setiferus aztecus aztecus aztecus setiferus setiferus aztecus setiferus Diaptomus tonsa-a nauplii tonsa-b sapidus detritus detritus 

A. A.
Palaemonetes Palaemonetes Palaemonetes Palaemonetes

P.P.P. P. A. A. C.
Organism 
Net 
P.P. P. P. P. 
Xanthidae Barnacle Trawl Trawl 
Type 
Sample plankton plankton plant plant plant POC POC POC POC POC sediment sediment sediment shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp zoopl zoopl zoopl zoopl zoopl zoopl zoopl crab plant plant 
Jan Nov Jan Oct Oct Apr Dec Feb Feb Jan Apr Feb Jun Apr Feb Jan Jan Jul Jul Jul Jul Jul Nov Nov Nov Oct Oct Oct Apr Apr Apr Feb Feb Feb Oct Jan Apr Nov 
6
Date 1985 1984 1985 1985 1985 1985 1985 1986 1986 1985 1985 1986 1986 1985 19-8 1985 1985 1985 1985 1985 1985 1985 1984 1984 1984 1985 1985 1985 1985 1985 1985 1986 1986 1986 1985 1985 1985 1984 
3 **s
Station 
0 
0«
603 603603 603603 603603603603603603'603 603603603 603 6036033603360360360360360360360603603603603603 603603613613613 
66 
del-N15 
4 .1 8 3 6.163 25 55.9
.9 .'3 .364 .1 
.. 
-23 -19.3 -22. -23,9 -23 -21.0 -18 -20.8 -20.42-2 -21.5 -23.2 -20.7 -25.9 -18 -17.9 -17. -25 -16, -22. -20.4 -21. -23. -23 -22. -16. -19 -17. -20. -22.5 -22.3 -23 -26.3 -24.0 -24.2 -•22.6 -23.9 -23.3 
del-C13 
part 
gut
Body gutstail tailtail tail guts guts gutstail tail muscletail skin+scalestail tail tail tailtail tail tail tail tail tailtail muscle muscle muscle 
3cm 2cm 5cm 2cm 5cm 5cm 5cm 5cm 2cm 2cm 5cm 2cm 2cm 6cm 5cm 1cm 5cm 
• 
. . .. ... 
-2-3cm 2-3cm 2.7cm cm 
. 
-
2.1.2. 2.
22 325 52 222
Size 3 
8888487472161422844664 81 11
12
il 
DOC DOC DOC DOC sp. POC POC POC
patronus undulatus patronus patronus lethostigma undulatus mitchilli lethostigma mitchilli mitchilliFundulus CyprinodonFundulus patronusFundulus patronus mitchilli undulatus patronus undulatusFundulus undulatus Cyprinodon undulatus Mediomastus Oligochaeta virginica cuneata cuneata detritus
Menidia 
B. B.B. B. B. B.
Organism 
M. M.A. A.A. A.M. M. M. M. C. Net
Rangia R. 
P. P. 
Sample 
Type DOC DOC DOC DOC fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish infauna infauna bivalve bivalve bivalve plankton POC POC POC 
Apr Aug Jan Mar Apr Apr Apr Apr AprApr Apr Apr Apr Jan Jan Jan Jan Jan Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Oct Apr Apr Apr Nov Nov Jan Apr Jan Mar 
Date 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1984 1984 1984 1984 1984 1984 1984 1984 1984 1984 1985 1985 1985 1985 1984 1984 1985 1985 1985 1985 
Station 
613 613 613 613 613 613 613 613 613 613 613 ¦613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 
5 5.3 7.51 
del-Nl j• 
9 0 .1 310
3 -25.5 -19.9 -19.4 -20.1 -19.0 -18.6 -19.1 -21.0 -21.4 -20.4 -22.3 -21.0 -22.0 -18.4-19.2' -20.5 -20.4 -23.8 -19.1 -24.0 -19.2 -25. -22.3 -25. -21.5 -19.0 -17.8 -18.3 -19 -21.2 -24.5 -20.1 -17. -18. -18. -19.7 -16.0
de1-C1 
part tail tail tail tail tail tail tail tail tail tail tail tail-tail tail tail tail claw whole muscle tail tail tail tail tail tail tail tail tail tail Body 
5cm 5cm 5cm 2cm 6cm 3cm 5cm 5cm 3cm 3cm 2cm 2cm 3cm 2cm 4cm 3cm 5cm 5cm 5cm 3cm 7cm 
. . .. ...
l-2cm 3.5cm 3.5cm small large 2-4cm
. 2. 6.
223 33 233
Size 
58611111111 11 4 241 3 1 6911
14 45 
II 13
200 11 
POC sp. sp. sp. DOC DOC DOC sp.

tonsa
sediment setiferus setiferus setiferus aztecus setiferus setiferus setiferus aztecus aztecus setiferus setiferus setiferus aztecus A. sapidus sapidus sapidus detritus detritus detritus patronus cephalus mitchilli patronus undulatus undulatus lethostigma GobidaeFundulus 
P. P.P. P. C.C.C. 
B.M. B.
Organism Penaeus Ictalurus
P.P.P. P.P.P. P.P.P. A. M.M.
Trawl Trawl Trawl
Palaemonetes Palaemonetes 
P. 
Type Sample POC sediment shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp zooplcrab crab crab plant plant plant DOC DOC DOC fish fish fish fish fish fish fish fish fish fish 
Oct Apr Apr Apr Jan Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Oct Oct Jul Apr Nov Nov Jan Jun Nov Apr Jan Mar Apr Apr Apr Apr Apr Apr Apr Apr Apr Jan Date 1985 1985 1985 1985 1985 1984 1984 1984 1984 1984 1984 1984 1984 1984 1984 1984 1985 1985 1985 1985 1984 1984 1985 1985 1984 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 
Station 
2 23
613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 613 623 623 623 623 623 623 623 623 623 3 623 623 623 623 623 623 623 623 
66 
5.7 4.9
del-N15 11.5 
486 1123356
4 41 96 
... . 
... 
. 
'. 
24
-16.2 -15.1 -18.3 -17.4 -20.7 -24 -16.7 -15. -21. -24.1 -22. -21.6 -17.9 -21.7 hO -21.2 -21.8--20.7 -19.4 -22.9 -24.7 -26 -26 -24 -21.2 -22.1 -22. -18. -18 -22. -19. -18 -19 -195 -19.0 -22,5 -23.7 
1--2
del-C13 
' 
part 
fat

tail tail tail tail whole tail tail tail tail tail tail tail tail tail muscle whole whole tails tail eggs tail tail tailBody 
6cm 2cm 2cm 1cm 5cm 3cm 4cm 5cm 5cm 2cm 2cm 5cm 2cm
s* 
5 
Size 2.7cm cm small large 2.5cm large
.. 
,
< 9> 32‘.2 2. 
< 
25 77 18441 47 2858 84 
li 10 10 17 101530
120 
tus POC POC POC 
tonsa zooea
Fundulus Cyprinodon cephalus Cyprinodon undulatus patronus CyprinodonFundulus undulatus patronusFundulus undulatus mitchilli Cyprinodon Nemertinea Laeonereis mitchilliLaeonereis virginica virginicaMussels virginica Ectocarpus sediment setiferus Amphipoda 

A.
Organism Mediomastus Heteromas Palaemonetes Macrobranchium Palaemonetes Palaemonetes Palaemonetes 
M.B. 
B. 

M. 
M. M.A. C.C. C. P. 


Xanthidae
Macoma 
Type 
Sample fish fish fish fish fish fish fish fish fish fish fish fish fish fish infauna infauna infauna bivalve infauna infauna bivalve bivalve bivalve bivalve plant sediment shrimp shrimp shrimp shrimp shrimp shrimp zoopl zoopl zoopl
POC POC POC Jan Jan Jan Jan Jan Nov Nov Nov Nov Nov Nov Nov Nov Nov Aug Aug Aug Jun Jun Jun Apr Apr Nov Nov Jan Apr Jan Mar Apr Apr Apr Apr Jan Nov Nov Jan Jul Jul Date 1985 1985 1985 1985 1985 1984 1984 1984 1984 1984 1984 1984 1984 1984 1985 1985 1985 1985 1985 1985 1985 1985 1984 1984 1985 1985 1985 1985 1985 1985 1985 1985 1985 1984 1984 1985 1985 1985 
3 2 
Station 
2 2 6 
623 623 63 623 623 623 623 623 623 623 623 63 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 623 
8.3 Q 6.0 
Q
del-N15 
-
0 0v 6' 
• 
.
%i 
y «. 
x
-18.9 -24.4 -19.2 -22.4 -20.9 -18.5 -23.3 -28 -19 -19.8 -20.4 -24.5 -17.2 -2 -19 -19.5w -20.5 -17.0 -22.6 -25.7 -21.9 -23.0 -20.6 vv -20.2 -23.6 -24.0 -23.9 -23.7 -22.3 -19.0 -21.3 -20.8 -19.8 -25.8 -23.7 -24.2 -20.2 -19.1 
x
del-C13 2.4, 
part body 
claw claw tail tail tail tail tail-tail tail Guts tail tail guts tail tail tail muscle muscle muscle guts whole 
Body 
whole 
cm cm
2cm 4cm 2cm 5cm 8cm 3cm 5cm 5cm 6cm 5cm 
*8 
Size 16cm 2-3 4,4cm 2.3cm 2.3cm 5-7cm
... . 
33293 1.9 
-3 
321 691512821331841111 7 
li 
DOC POC POC 
mitchelli minor mitchilli lateralis sapidus sapidus sapidus detritus undulatus patronus lethostigma undulatus mitchilli cephalus undulatus cephalus cephalus mitchilli mitchilli marina undulatus mitchilli nebulosus mitchilli lateralis mitchilli Mediomastus Corophium Ampelisca GlyceraLaeonereis Edotea Coleoptera sediment sediment 
C. C. C.
Ensis 
B. M. M.M.
Organism Bagre
M. M.M. M. M.A. M. A.A. M.A.C.M.M.M.
Trawl 
P. 
Type 
Sample bivalve bivalve bivalve bivalve crab crab crab plant DOC fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish bivalve bivalve bivalve infauna infauna infauna infauna infauna infauna insect POC POC sediment sediment 
Apr Feb Feb Feb Apr Apr Jul Jul Apr Apr Apr Apr Apr Apr Apr Apr Apr Jul Jul Jul Jul Jul Oct Oct Aug Aug Aug Feb Feb Feb Feb Feb Feb Apr Apr Feb Apr Jun 
Date 1986 1986 1986 1986 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1986 1986 1986 1986 1986 1986 1985 1985 1986 1985 1986 
333333 3 3 333 
333
Station 
33333 3 3 
3333 3
633633633636336633663366,366363363363366336336336633633633633633633 6 6633663363633633 633 
66 3 
del-N15 12,. 
205 2 229105 L39
.'8 J 
. tt 
.. 
X 3J 
w
-24.8 -17.8 -21.8 -20.5 -22.3 -22 -26. -23 -25.8 -19 -24. -18.0 -24.1 -24.6 -28.2 -24.0 -22.7. -22.4 -21.9 -21.2 -17.5 -26. -23. -21. -20. -22.6 -21. -22 -23.6 -22.9 -19.4 -17.6 -17.9 -21.2 -18.9 -2 -20 -24.5
C
del-C!3 
part tail tail tail tail tail claw whole claw tail guts tail guts guts tail tail tail tail tail whole tail whole tail tail tail tail tail tail tail Body 
cm cmcm
5cm 3cm 5cm 5cm 6cm 5cm 5cm 2cm 2cm 5cm 5cm 3cm .,5cm 5cm 3cm 
.1.8 44
5-7cm 5-8cm -l-2cm 2.5cm
. .. , 
-0.2 .4 2. 2.1-1 2 . 
41 3
Size 2.5-3cm 4-5. 2.5-3cm 2-2
2-. > 
4 
32 968 11 6118313 826 25 686
4 11
10 65 1412 10 
il 
105 125 
DOC DOC DOC
tonsa tonsa felis
Mysidae aztecus setiferus nauplii sapidus sapidus sapidus detritus detritus detritus undulatus cephalus cephalus patronus undulatus undulatus mitchilli patronus mitchilli undulatus undulatus Fundulus Cyprinodon Fundulus Menidia cephalus undulatus patronus undulatus
A.A. A.
Organism Macrobranchium Palaemonetes Palaemonetes 
P. C.0. C. 
M. M.B. B. M. B. 
P. M. M. M.A. A.M.M. M. M.
Trawl Trawl Trawl
Barnacle 
Type Sample shrimp shrimp shrimp shrimp shrimp shrimp zoopl zoopl zooplcrab crab crab plant plant plant DOC DOC DOC fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish 
Apr Apr Feb Jul Jul Jul Feb Feb Oct Apr Jan Nov Apr Jan Nov Apr Jan Mar Apr Apr Apr Apr Apr Apr Apr Apr Apr Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Nov 
5 54 
88
Date 1985 1985 1986 1985 1985 1985 1986 1986 1985 1985 1985 1984 1985 1985 1984 198 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 19 1985 19 
Station 
5555 55555 555555 5555 5 555r
55 C5r 6666 66666 6 
633 633 633 633 633 633 633 633 633 65 65 65 /<•
666666 6666666r666 
7.9 9.2
del-N15 11.2 
-
3 5 3J 1i 0V 4T0v24 0v 
.• »•••« • 
41 v4JV1X X 
“
20 21
2fa 2w XX24 X
-16 -16.4 -23.1 -15.8 -15.0 -17.1 -23.8 -23.4 -27.1' -26.6 -24.2 -24.5 -29.2 -27.6 -21.0 -22.5 -20.7 -25.0 -19 -21.1 -18.6 -21.9 -19.5 -18.5 -18.8 -21.3 -22.2 -23.4 -21.4 -21.7 -21.0 -23.1
2
del-Cl 
body
part 
+
tail tail tail tail tail muscle tail whole whole whole tail tail tail tail tail tail tail tail tail claw claw muscle whole 
Body 
claw 
cm
5cm 6cm 5cm 5cm 5'dm 3cm 4cm 2cm 5cm 7cm 5cm 2pm6cm 2cm 
* 
3”4cm, 6cm large
... . 
2. < 
333 52
Size -3 
2. 
1121181 458 11111 21214 II 
10 
sp. sp.• tow Iva POC POC POC sp.
pupae 
Organism Cyprinodon Fundulus mitchilli CyprinodonFundulus Menidia undulatus Oligochaeta Tellina lateralis cuneata sediment Macrobranchium Macrobranchium Palaemonetes Palaemonetes setiferus setiferusPalaemonetes setiferusPalaemonetes mitchelli mitchilli lateralis lateralis Tellina sapidus sapidus sapidus sapidus sapidus 

R. C.C.C.C.C. 
A. M. M. P.P. P. M.M.M.M.
Chironomid Mediomastus Net 
Type 
Sample fish fish fish fish fish fish fish infauna bivalve bivalve infauna infauna bivalve plankton plant POC POC POC sediment shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimpbivalve bivalve bivalve bivalve bivalve crab crab crab crab crab 
Nov Nov Nov Nov Nov Nov Nov Apr Apr Apr Apr Apr Nov Nov Jan Apr Jan Mar Apr Apr Apr Apr Jan Nov Nov Nov Nov Nov Feb Apr Apr Feb Oct Apr Jan Jul Nov Nov Date 1984 1984 1984 1984 1984 1984 1984 1985 1985 1985 1985 1985 1984 1984 1985 1985 1985 1985 1985 1985 1985 1985 1985 1984 1984 1984 1984 1984 1986 1986 1986 1986 1985 1985 1985 1985 1984 1984 
Station 
5?•555r 555 5555 555555 5 555r5
6565 /•*6 /•666666565 65656666565 858588 8585
6
656 66 656 666 6 8 8585 
d
8 
1X 
7.3 5.2 
11.7 11.7 10XV# 14.2 13.9 13.4 12.6 
del-N15 
98 96 77 4 306 4229692 2 J7/ 
....t i 
... ... 
. 
4* i.
-27.2 -26.4 -21.0 -26 -22 -22.8 -21. -19 -20.6 -19. -20. -22.0 -19 -17.7' -21. -21. -18 -19 -16 -22 -18 -17 -20 -17. -18. -22.3 -20.0 -20,9 -22.6 -23 -24.8 -20.2 -20.4 -21.7 -22.9 -21 -22.2
W
del-013 .1 
part guts guts tail gutstail tail guts guts tail tail guts tail tail tail tail tail tail tail whole tail whole tail tail guts guts guts tail tail tail tail tail guts 
• .
Body 
cm cmcm
6cm 6cm 6cm 2cm 6cm 6cm 5cm 5cm 2cm 2cm 3cm 2cm 2cm 5cm 2cm 7cm 5cm 5cm 7cm 5cm 4cm 
6 65 
12cm 
... .
3.5cm 
.. . 
3, 2.2.2. ­
2 2222 7 34
Size -­
33 
91 166 19 17 3453911 11251
7 146
10 10 
II 
DOC DOC sp. sp. sp. sp. 
felis felis
detritus detritus detritus detritus mitchilli mitchilli undulatus patronus mitchilli undulatus undulatus Fundulus Fundulus mitchilli undulatus patronus Cyprinodon patronus cephalusFundulus undulatus cephalus patronus xanthurus nebulosus mitchilli Gobidae undulatus mitchilli nebulosus

A. A. 
B. B. B.M. M. B,
Organism Menidia Menidia Symphurus Symphurus
A.A.M. A.M.M. A.M. M. C.A. M.A.C.
Trawl Trawl Trawl Trawl 
Leiostomus 
Type Sample plant plant plant plant DOC DOC fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish 
Apr Jan Nov Oct Aug Jan Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Jan Jan Jan Jan Jan Jan Jan Jan Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Date 1985 1985 1984 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 
Station 
5 555555555 5 5 
5 555
8585858585858588585 8,58 8 8 8 8588588585 858585858 8585 85
8
8888 8 8588 
3V 3J 
7.6 10.7XV.1 10V 13J 
XX
del-N15 . . 
'¦ 
3 122 J 6SJ / fa7/
.1 .1 
. 1 i•tI .. 
«*> X VVi 
W 21 X 91w
XM •
-18 -23 -19 -20. -23 -22.5 -23 -22.3 -20.2 -21.9' -19.9 -21,9 -22.3 -22.5 -20.0 -14.9 -22.4 -22.7 -22.0 -21.9 -22.9 -19.9 -17,6 -19.3 -19.9 -20.5 -22.7 -21.6 -21.6 -23.3 -22.1 --25.5 -23.2 -26.7 -26.2 -20.5
del-013 
part tail tail tail tail tail tail. tail tail tail tail tail tail tail tail tail fat muscle whole whole Body 
8cm 5cm icm 2cm 5cm 5cm' 8cm 2cm 
V
3.5cm 3.3cm mixed 2.7cm 3.3cm mixed.
... ... 
.. 
422 23 434 
<> 

Size ' 
338 6
1845 10 
II 
tus tow 
Net
Cyprinodon undulatusFundulus undulatus undulatus undulatus undulatus undulatus sp. mitchilli Cyprinodon undulatus undulatus undulatus mitchilli capitata Edotea Laeonereis Edotea Mediomastus Scotolana Ampelisca Glycera Nereis Edotea larvae Loandalia Streblospio Hobsonia Edotea virginica virginica mussel virginica Ctenophora
Menidia Mediomas Mediomastus
Organism 
M. M.M.M.M.M. A. M.M.M.A. C.C. C.
Glycera Chironomid 
Type 
Sample fish fish fish fish fish fish fish fish fish fish fish fish fish fish fish infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna infauna bivalve bivalve bivalve bivalve plankton zoopl 
Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Oct Apr Aug Aug Aug Feb Feb Feb Feb Feb May May May May May May May Oct Apr Apr Nov Nov Jan Jan 
4 
8 

1984 85
Date 19 1984 1984 1984 1984 1984 1984 1984 1984 1984 1984 1984 1984 19 1986 1985 1985 1985 1986 1986 1986 1986 1986 1985 1985 1985 1985 1985 1985 1985 1985 1985 1985 1984 1984 1985 1985 
Station 
55 5555 555 555 55555 5 5555 5 5
5
85858 88858 858588 8885 88 85 8 8585
8 8588 88 8 85888 885888858 
7 6V/ 
5v
12,2 ¦10 11.7 9J 7
XXI 10XV 
X
del-NlS • % 
A 3 4 6V0v5yj J *v 9 4 yj X 9J V 4*14*1 5-J5yj5J8 
. I•1%•. • %\ # %. •.
1 •• 
24x2C J Cm X X3-J V yj 2Cm X4H
1 
/ 21
-28 -14.7 -20. -23.8 -19.9 -17.4 -19.9 -24,0 -18 -19.3, -24.2 -25. -19.1 -21.6 -21.3 -18.8 -19.3 -22,5 -23.4 -22.3 -22.2 -18.8 -19.7 -21.1 -21.71 -20.5 -19,0 -25 -24 -20.6 -24
242Cm2 X x Cm c* Cm2Cm Cm Cm Cm 2Cm Cm2Cm
Cm
del-C13 
part .gland 
viscera 
guts tail tail tail tail eggs tail tail tail guts guts tail tail tail chitin tail tail tail muscle
Body 
green 
head 3cm 2cm 3cm 4cm 3cm 3cm 5cm 5cm 2cm 8cm 4cm 
1
7-8cm 4-5cm large small
. ... 
2 276
Size 2.5-3cm 
63611 8555 431 8 
It 1010 
125 150 120 133 tow POC POC POC tes 
tonsa tonsa tonsa 
Net
Enteromorpha Cladophora Cladophora s.ediment sediment setiferusPalaemonetes MysidaePalaemonetes Palaemonetes setiferus setiferus aztecus aztecus Palaemonetes setiferus setiferus setiferus setiferus aztecus brevis nauplii Amphipoda Ctenophora Ctenophora

, 
A. A.A. 
L. 
P.P. P.
Organism Palaemone Macrobranchium Macrobranchium Macrobranchium Macrobranchium Macrobranchium
P. P.P. P.P.P.P. 
Barnacle 
Type 
Sample plankton plant plant plant sediment sediment shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp shrimp squid zoopl zoopl zoopl zoopl zoopl zoopl zoopl
POC POC POC Nov Apr Jan Jul Apr Feb Jan Apr Jun Apr Apr Apr Apr Apr Apr Apr Apr Feb Jan Jul Jul Jul Jul Jul Nov Nov Nov Nov Oct Oct Oct Feb Feb Jan Jul Oct Oct Oct Date 1984 1985 1985 1985 1985 1986 1985 1985 1986 1985 1985 1985 1985 1985 1985 1985 1985 1986 1985 1985 1985 1985 1985 1985 1984 1984 1984 1984 1985 1985 1985 1986 1986 1985 1985 1985 1985 1985 
Station 
555555 55 
5
85 85585885 858585858 8S8858588585888858585 8585 85 85858885858585885 8585 
5 C5 
2.1 9 7.3 2.5 
O
o1
12.2 16.2 16.2 13.0 12.5 13.0 
X
de1-N1 • » 
¦' 
3 
-26.5 -19.5 -21.6 -24.2 -25.0 
de1-C1 
part Body 
Size 
58 
II 
DOC DOC POC POC 
cuneata abdita Ulmus
Paracalanus Cladophora Mediomastus Mediomastus Mediomastus Mediomastus Mediomastus Mediomastus Cladophora

Organism 
R. Ampelisca 
Type Sample zoopl DOC DOC POC POC plant plant plant 
Oct Dec Oct Dec OctOct Nov Apr Apr Apr Apr Apr Apr Feb Nov Aug 
Date 1985 1985 1985 1985 1985 1985 1984 1986 1986 1986 1986 1986 1986 1986 1984 1986 
5
Station 85+633 85+633 85+633 85+633 5/36
5 3,3 0 23 
85 603 603 854 603615 190536 
555 22 60v 98 942835195 34 2X8 
.;•• • 
9 66
2. 11,5 8. 14.6 J 13.2 11.75. 11.9 9.4.1 .7.3 6. 16.5. 5. 12.8w 10.8 12. 13.8 \J3. 2.1
11, 12. 11. 10. 13X• < 13 12. 12. 16X 
V
del-N15 
432 3 8 07235 
.. 
.
-20.1 -23 -20. -20.6 -20 -18.7 -19.7 -18.6 -18.8 -17-. -20.5 -23 -17.5 -17.4 -26.7 -25.5 -22.8 -24.1 -23.7 -24.3 -26. -24. -24 -21. -20.
del-013 . 
. 
part 
whole muscle tail tail claw tail tail tail tail tail guts tail tail tailBody 
5cm 5cm 5cm 
7 
. ..
Size large large large 5-8cm 3-4cm 7-8cm cm 14cm 
3 23 
225 4111 444441 
If 10 
7.9 Ulmus calif virg. abdita larvae stick
Organism Maldanidae virginica lateralis undulatus limicola Mediomastus americana Ogyrides sediment setiferus sapidus undulatus variegatus variegatus Mediomastus australis detritus Macrobranchium Macrobranchium cuneata lethostigma lethostigma undulatus lethostigma Mediomastus Cladophora Cladophora
TABLE off 
C. R. 
C.M.M. G. P. M. M. 
C. C. 
Trawl 
P.P. P.
Mediomastus Crassostrea Ogyrides Ampelisca Chironomid Algae
Phragmites 
Type 
Sample plant infauna infauna bivalve bivalve bivalve fish infauna infauna infauna infauna sediment shrimp infauna crab fish fish fish infauna infauna plant plant plant shrimp shrimpbivalve fish fish fish fish infauna plant plant 
Aug Feb Apr Nov Nov Feb Nov Oct Apr Feb Feb Apr Nov Feb Nov Nov Nov Nov Feb Apr Jan Jan Oct Jul Apr Nov Jul Jul Jul Apr Apr Oct Oct 
8-4
Date 1986 1986 1986 1984 1984 1986 1984 1985 1986 1986 1986 1985 1984 1986 19 1984 1984 1984 1986 1986 1985 1985 1985 1985 1985 1984 1985 1985 1985 1985 1986 1985 1985 
5 
03 
555555 555 0 
Station 1505 1505 1905 1905 1905 1905 1905 1905 1905 1905 1,9 1905 5/36 4 4 45 4 4 4 603 6 603 603 603 603 603 603 603
5 
344 
44 4 39 3339 2417 2 
5 5. 4. 7.
5.34.711.710.29.710.211.57.3 5.7 8.313.09.96.0 10.7 9.211,27.6 .9 11.711.12.612.212.5.2
12. 13. 10. 14. 13 13-. 10. 
¦' 
‘
del-Nl 
36422 7
229182 .1 98 8 
. ... ... . . 
..
-26.5 -21.8 -22.5 -23. -23 -23 -26.8 -25 -24 -18 -22 -20 -20 -24.8 -26 -23.2 -25.5 -22 -23 -21.7 -18.3 -20.2 -21.7 -22 -24 -23.2 -20.0 -21. -23 -26.4
del-C13 . . 
. 
part 
fat
tail tail tail tail whole tail whole muscle whole claw tail tail tail tail guts guts tail tail
Body 
\ 
5cm 5cm 2cm 6cm 7cm 7cm 4cm
12cm
7-8cm 6-7cm 3.5cm 4-5cm
--< 4
3 < 
Size 
24767 2 3 42126611 
If 

10 10 
felis
Organism detritus sediment setiferus setiferus aztecus aztecus virginica Cladophora detritusEctocarpus sediment lateralis Mediomastus Laeonereis sediment virginica virginica virginica lateralis sapidus sapidus Cyprinodon undulatus mitchilli mitchilli nebulosus xanthurus nebulosus Mediomastus Cladophora detritus 

A. 
P.P. C.C.
Macrobranchium

P.P. C. M. C.C.C.M. M.A.A.C. C.
Trawl Trawl Trawl
Leiostomus 
Type 
Sample plant sediment shrimp shrimp shrimp shrimp bivalve plant plant plant sediment bivalve infauna infauna sediment shrimp bivalve bivalve bivalve bivalve crab crab fish fish fish fish fish fish fish fish infauna plant plant 
Jan Apr Nov Jul Jul Jul Nov Nov Jan Jan Apr Feb Apr Feb Apr Apr Nov Apr Apr Feb Nov Jul Nov Jul Jul Jul Jul Jul Jul Jul Apr Jul Jan Date 1985 1985 1984 1985 1985 1985 1984 1984 1985 1985 1985 1986 1986 1986 1985 1985 1984 1985 1985 1986 1984 1985 1984 1985 1985 1985 1985 1985 1985 1985 1986 1985 1985 
Station 
3 3'3
3 5 555555
555
603603603603603623623623 623623 633 633 633858585 8 88858585858
66 88888 85
8 
l'i 7.6
,Hn'v 10.6
l-«5 
de 
’
C13 1 
-is'g -21 -222 “20.6
' 
del . 
Part 
tail tail tail '5cm -8cm
small 
47 
858 
" 
11Sm ment rus ecus 
' 
l9a 5f^ 
o,-detritus ®®fi fetiferus
Amphipoda
a 
i 
’ ‘ 
p 
pP
Trawl pP 
Type 
t 
* 
a
sample sediment shrimp shrimp shrimp toopl
„i 
w 
Apr Apr Nov Jul Jul Jan 
Date 1985 1985 3984 1985 1985 1985 
Station­
85 85 85 oc88