I I I PART I I Production ecology of Ruppia maritima L. s.l. and Halodule wrightii Aschers. and the biomass of associated macrophytes in two south Texas estuaries I FINAL REPORT I to the Texas Water Development Board I P.O. Box 13231 Capitol Station Austin, Texas 78711-3231 I from I Ken Dunton The University of Texas at Austin Marine Science Institute I Port Aransas, TX 78373 I I I December 1989 Technical Report No. TR/89-012 I I I I I I 2 I ACKNOWLEDGEMENT In response to House Bill 2 (1985) and Senate Bill 683(1987), as enacted by the I Texas Legislature, the Texas Parks and Wildlife Department and the Texas Water I Development Board must maintain a continuous data collection and analytical study program on the effects of and needs for freshwater inflow to the State's bays and estuaries, I as part of the mandated study program. This research project was funded through the Board's Water Research and Planning Fund, authorized under Texas Water Code Sections I 15.402 and 16.058( e ), and administered by the Department under interagency cooperative I contract No. 9-483-706. I I I I I I I I I I I 3 I ABSTRACT I Seasonal growth and production dynamics of Ruppia maritima L. s.l. were compared I over a three year period in two south Texas estuaries that were characterized by different salinity and nitrogen regimes as a result of freshwater inputs. Continuous measurements of shoot production in the higher saline Nueces Estuary (32 -38 °loo) and the lower saline I Guadalupe Estuary (0 -25 °loo) revealed no major differences in the magnitude of growth, but the plant populations differed significantly in the seasonality of growth, the time of I flowering and the persistance of an overwintering population. During the period of rapid I shoot development, from March to August, growth rates usually ranged from 2-4 mm day91 (0.04 to 0.08 mg dry wt mg shoof1 day91), although peak growth rates of up to 8 mm I I day-1 were also recorded. At the high nutrient site in Guadalupe Estuary, a combination of heavy fouling by epiphytic macroalgae and wave exposure prevented the establishment I of an overwintering population compared to the less exposed higher saline site in NuecesI Estuary. As a result, R maritima was a strict opportunist, with a monocarpic reproductive pattern, yearly colonizing bare areas and completing its entire growth cycle in four months. I Halodule wrightii Aschers. was absent from Guadalupe Estuary, but simultaneous I measurements of growth in H wrightii in the Nueces Estuary revealed a nearly opposite strategy which included the presence of large overwintering populations, with a significant I proportion of the plant's total biomass contributed by its roots and rhizomes. For R I maritima these results indicate that large changes in salinity and nutrient regimes, as caused by increased freshwater inflow, have little direct effect on the growth of this euryhaline species, but could, under extreme conditions, produce an environment that prohibits its I establishment as a result of fouling by epiphytic algae. I I 4 I INTRODUCTION I I Despite the widespread occurrence and abundance of the submergent halophytes Ruppia maritima L. and Halodule wrightii Aschers throughout Gulf of Mexico coastal habitats, no long-term measurements of net production are available in relation to in situ I environmental parameters. Annual or seasonal net production of aquatic macrophytes is often estimated by harvesting above-and below-ground biomass, an indirect technique that I assumes losses of plant material during the growth season are negligible (Westlake, 1965). I But studies have demonstrated that annual net production can significantly exceed maximum biomass in many species due to losses of plant biomass during the growth season I from natural senescence (Mann, 1972; Roman and Able, 1988), epiphyte loading (Kiorboe, I 1980) or from grazing (Roman and Able, 1988). I In addition, few studies of rooted macrophytes have presented data for more than oneI consecutive year. Often, what is thought to be average growth in a "typical" year may not, in fact, reflect the dynamic state of the · habitat and the importance of various I environmental factors. Such factors include the effects of water temperatures, nutrients,I salinity and irradiance on macrophyte growth (McRoy and McMillan, 1977; Drew, 1979; McMillan and Phillips, 1979; Harrison, 1982). As a result, knowledge of how aquatic I vegetation responds to short-and long-term changes or conditions in their natural habitat I is lacking and makes effective management of the coastal habitat difficult. In this study, I examined the growth response of Ruppia maritima in two south Texas estuaries that are characterized by different freshwater inflow regimes over a three-year I period. Continuous measurements of shoot production were correlated with in situ changes I I 5 I in water temperature, salinity, ambient dissolved inorganic nitrogen (DIN), underwater light, and algal epiphyte biomass and species composition at the various experimental sites. I Differences in the strategy of growth between R maritima, an annual, and Halodule I wrightii, a perennial, were compared through measurements of shoot production and biomass over a coincident two-year period at a site where both species co-existed. I Seasonal and annual differences in the timing of maximum biomass and fruiting in R maritima among three estuarine sites were also examined. I I METHODS I Study sites I I Four sites were established in this study, two in San Antonio Bay in the GuadalupeI Estuary, and two in Corpus Christi Bay in the Nueces Estuary (Fig. 1). The two sites in San Antonio Bay, Seadrift (SD) and Blackjack Peninsula (BP), were dominated by pure stands of Ruppia maritima to 0.4 m depths. Sediments at Seadrift at 0.3 m were 89% sandI and shell, 2% silt, and 9% clay. In Corpus Christi Bay, East Flats (EF) consisted entirely I of Halodule wrightii, but at Indian Point (IP), both species occurred in both pure and mixed stands. At Indian Point, monotypic stands of Halodule occurred throughout the deeper and I shallower areas of the subtidal zone, from 0.3 m to 0.7 m depths. Ruppia occupied a zone I between these two beds, at a 0.3 m depth, which occassionally (usually in the autumn) I I I I I I I I I I I I I I I I I I I Figure 1. Map of the south Texas coast, showing location of the study sites in San Antonio Bay (Seadrift, SD; Blackjack, BP), and Corpus Christi Bay (East Flats, EF; Indian Point, IP). I I I 7 became mixed with Halodule for a short period. Sediments at Indian Point at 0.3 m depths I were 86% sand and shell, 8% silt and 6% clay in the R maritima community, and 74% I sand and shell, 14% silt, and 12% clay in the shallow H wrightii community. Both study sites in Corpus Christi Bay (IP and EF) were relatively protected from waves and adverse sea conditions. East Flats was located on the southeast side of a small I inlet, and the seagrass community at Indian Point was located behind several shallow offshore sand bars on the northwest side of the bay. The presence of the sand bars I permitted luxuriant growth of both species in protected, quiet waters. In contrast, the sites I in San Antonio Bay were more exposed. Seadrift received the full force of winds and I waves that developed from the south, which were only partially dissipated by offshore I islands and shoals. Blackjack Peninsula was located on the west side of the Gulf Intracoastal Waterway (GIWW), and was therefore exposed to wave surges from passing barge and ship traffic. I I Production and biomass measurements I I Measurements of shoot production and biomass were made at the shallow (0.3 m) and deep areas (0.4 to 0.6 m) at each site except East Flats (0.4 m only). At each depth, and I at 2-4 month intervals, three biomass samples of 0.0064 m2 were randomly collected with I a 9.0 cm diameter coring device where grass cover appeared uniform and dense. Samples were thoroughly cleaned of epiphyte material in the laboratory, separated into above ground and below-ground biomass and dried at 60° C to a constant weight. Estimates of I shoot production were obtained at 3-6 week intervals using the leaf-clipping technique I I 8 I described by Virnstein (1982). This is a cut and harvest approach that requires clipping a small area of shoots directly above the basal sheath, allowing re-growth, and then collecting I cores of the clipped area to measure net growth. Estimates of epiphyte biomass were usually made from three replicate leaf samples I taken adjacent to the biomass cores. Epiphytes were separated from the leaf surface in I the lab by scraping with a scalpal and transferred to Whatman GF/C filters (Borum et al., 1984). This procedure removes >90% of the epiphytic algae at low density (Borum et al., I 1984). The species composition of algal epiphytes was determined from subsamples of I collected blades. I Estimates of drift macroalgal biomass were made by harvesting all the algae withinI randomly thrown 0.1 m2 frames at two sites in Corpus Christi Bay, East Flats (Fig. 1) and Fin and Feather, located 4 miles northeast of East Flats in Redfish Bay. Since the seagrass I beds at both sites are characterized by a natural progression from Halodule wrightii in I shallow water to Thalassia testudinum and Syringodium filiforme in deeper water, drift algal biomass was examined in each habitat type based on ten tosses of the frame in June 1988. For each toss, all the drift algae within the volume of water determined by the frame was I I harvested and placed in a labeled bag. In the laboratory, the algae within each bag were sorted by species, identified and then rinsed in fresh water to remove excess salt. They were then oven-dried at 60°C and weighed on an electronic balance to the nearest 0.01 g. I I I I I I I I 9 Irradiance measurements I Measurements of photosynthetically active radiation (PAR = ca. 400-700 nm) were I collected continuously on a remote basis at Seadrift (0.4 m), East Flats (0.4 m), and Indian Point (0.6 m) in 1988. PAR was measured at one minute intervals and integrated on an I hourly or 3-hourly basis. Coincident measurements of incident PAR were made at nearby shore-based field stations using a LI-190SA quantum sensor and datalogger. The sensorI was mounted so as to minimize shading from nearby vegetation or structures. To test for I significant differences in PAR among sites, statistical analyses were performed on a microcomputer using a one-way block design (ANOVA) model. Tukey multiple I comparison procedures were used to find a posteriori differences among station means. All I analyses were performed using SAS software (SAS Institute, 1985). Levels of total ambient DIN (N03-+ No2• + NH4 +)from water samples collected I near each site were determined according to Strickland and Parsons (1972). I I I I I I I I I I 10 RESULTS I Production dynamics I There was little difference in the growth rate of Ruppia maritima at Seadrift and I Blackjack sites in San Antonio Bay, despite the large differences in ambient DIN and salinity regimes between the two sites (Fig. 2). Water salinities were frequently much I I lower and levels of ambient DIN were consistently higher at Seadrift than at Blackjack. Water temperatues at the two sites were nearly identical. Shoot growth at the shallower (0.3 m) and deeper (0.4 m) locations at each site also did not differ significantly. I I The period of maximum growth in Ruppia maritima at all three sites (Blackjack, Indian Point, and Seadrift) occurred during the late spring/early summer period (Figs. 2; 3)~ In I 1987, a distinct increase in growth from depressed winter levels occured by May, when I growth rates of 7-8 mm day"1 were recorded. However, shoot growth usually ranged between 2-4 mm day"1 (0.04 to 0.08 mg dry wt mg shoor1 day"1) during the period of I maximum growth in 1988 and 1989. The high growth in May 1987 corresponded to a I period of exceptionally low daytime tides, high ambient DIN concentrations and lowered salinities that resulted from increased river inflow during a wet spring in south Texas. The period of maximum growth in Halodule wrightii also coincided with a noticeable increase I in water temperatures at Indian Point (Fig. 4). Growth of Halodule wrightii reaches a peak of 4 to 6 mm day"1 ( 0.13 to 0.21 mg dry wt mg shoot day"1) by early summer at a I I I I I I I I I I I I I I I I I I I Figure 2. I I TOTAL INORGANIC NITROGEN 417 z 200 0 • -• SEADRIFT 11 ~I o-o BLACKJACK 0:::: 1--~ ~ 7100 u C' ~~ (.) g 40 j\ •-• SEADRIFT ........ 0 30 o-oBL.ACKJACK /0.......~ <>--o-'o 0-0...,,0/ • ~ 20 z ::i < 10 / o')\1\J~ U1 0 ~"-'--==~~...-;:::::i;;;;;;~~-&..!!~--1--1........!!...--1...-.1..---1.---1.----L--J--J--Jt....-:J U A U J J A S 0 N D J F U A U J J A S 0 N D .J 0 u 40 •-•SEADRIFT ~ 30 /~~oBLACKJACKl!~-~......._., :J !:( 20 a::: . ~ ~ w 0... 10 ~ w 1--0 L-..L.-..L...-...l-....L..-.....l..---1---1.---1.-....1.-....l.---l--l--l-----L..-l...__.i..--J..--i.---L--'----A--' U A M J J A S 0 N D J F M A U J J A S 0 N D J 10 Ruppia maritima -shallow (O.J m) T 0 8 e-eSEADRIFT 0-0 BLA.CKJACK 6 Ruppia maritima-deep(0.4 m) 0 e-eSEADRIFT O -·-0 BLA.CKJACK 6 ~ 4 r-~ 2 ........ \/. '\. .t~~~~y.~ .--::::::::. 0 L_.1.-.-.1--.1--..1.....-..1....-...L.-...L.-..i......!!~:C:::::tlh::::~...:..,__.i__.i__.i_...:..._...:..._~..J.....-,.J M A M J J A S 0 N 0 J F M A M J J A S 0 N D J 1987 1988 Ruppia maritima. Aspects of shallow and deep shoot growth with respect to total ambient DIN, salinity and temperature at Seadrift and Blackjack. I •-•SEADRIFTTOTAL INORGANIC NITROGEN z o-oBLACKJACK 0 120 •-•INDIAN PT. I ~ 90 a::: ~~60 12 ~ :t30 I z ot..:....L--..&--1.._._!:L__._:~~~~~~~::...:...__._~~a;::::;::..-......__,__....__.._~--'llll~.-Jl.I~~ 0 ...... u MAMJJASONDJFMAMJJA S 0 ND J FM AM J J AS 0 I I I I I A M J J A S 0 N D J F M A M J J A S 0 N D J F M A M J J A S 0 I 10 T 0 Ruppia maritima -shallow (0.3 m) 0.20 I 8 , 0.15 1,,, : 0.10 .g /o l •-• E I l\ ! I E 2 _. 0t-• ~'-_lo-o):~-6-~ t .._/<''.1.;( 0.05 z E O 0.00 0 M A M J J A S 0 N D J F M A M J J A S 0 N D J F M A M J J A S 0 I 1 I u ~ 8 ::J •-•INDIAN PT. (0.3 m) 3: Halodule wrightii 0.30 0 6-6INDIAN PT. (0.6 m) et: 6 A.-• ~ C) I 0 0 0.20 Q_ ~ 4 r ~ o 0 I 0 I ,. l I 2 ~6-K~· ~<"l-_. 0.10 0 _// _ 6 _.,,1 .-/cs' A-:::::-...~---'¥ 6 ..t. U1 (f) ---· 0.00 I MAMJJASONDJFMAMJJASONDJFMAMJJASO I 0 1987 1988 1989 I Figure 3. Ruppia maritima and Halodule wrightii. Aspects of shoot production and growth with respect to total ambient DIN, salinity and temperature at Seadrift, I I Blackjack and Indian Point. Values for shoot growth are x±SE(n=3 to 4). Corresponding values for shoot production are shown on the right axis and followed the same trend as depicted for shoot growth. I 13 Halodule wrightii e-eIndian Point (0.3 m)I 8 7 0-0Indian Point (0.6 m) I 6 I ~~ 01 I 5 4 0:::: >. '-' 0 I-'"O o E 3 I o E I (/) I 2 0 L-----L~---L-~-L----JL----L-~-'-~....____,_~__._~~~'--~~~ I D J F M A M J J A S 0 N D J I 1988 0.30 I Halodule wrightii e-eIndian Point (0.3 m) 0-0Indian Point (0.6 m) z 0 I 0.20 1 I u~ :J I 0 >. 0 0 0:::: '"O 0... O'I I-EI 8 0.10 I I (/) I 0.00 L--~~-'-~_.___.._____._~_,_~....____,_~__._~~~'--~~~ D J F M A M J J A S 0 N D J I 1988 Figure 4. Halodule wrightii. Seasonal patterns of growth and production of shallow and deep habitats at Indian Point (Corpus Christi Bay) from November 1987I through December 1988. I I I I 14 depth of 0.3 m. Plants in deeper water (0.6 m) displayed very similar rates of shoot growth I on a seasonal basis, except during summer when maximum growth rates averaged only 3I 4 mm day-1• At East Flats, growth of H. wrightii closely matched that of the shallow Indian Point site for the identical one year period (data not shown). Vegetative biomass of Ruppia maritima showed large seasonal changes at all three I estuarine locations (Fig. 5). Above-and below-ground biomass was lowest during the winter and early spring months, and highest during the early autumn. Maximum shoot I biomass approached 200 g dry wt m-2, compared to 100 g dry wt m-2 for roots and I rhizomes. At Seadrift, plants disappeared entirely in winter 1988 and 1989. At Indian Point, a reduction in plant density and size occurred following flowering, but complete loss I of vegetative biomass did not occur. In contrast, Halodule wrightii always maintained a I substantial root and shoot biomass (Fig. 6), regardless of season, at both Indian Point (0.3 I and 0.6 m depths) and East Flats (0.4 m). Maximum shoot biomass in H. wrightii wasI nearly 70 g dry wt m-2,compared to over 200 g dry wt m-2 for roots and rhizomes. As a result, a significant proportion (50 to 85%) of the total biomass in H. wrightii is contributed I by its roots and rhizomes. In contrast, root-rhizome biomass was quite variable in R. I maritima, and often made up a considerably smaller proportion (20 to 70%) of the total plant biomass. I To determine if there was any significant positive or negative relationship between I production in Ruppia maritima and salinity, temperature, and ambient dissolved inorganic nitrogen (DIN) at either Seadrift or Indian Point, six regression analyses were performed. The results of these analyses are shown in Table 1. With one exception, none of the I correlations are statistically significant. The one exception is the positive correlation I I I I I I ,,-...._, N I I E I I (./) (./) I <( 2 0 OJ I I I I I I I Figure 5. I 250 (./) 200 l o 0 I 150 (./) 100 50 200 150 (./) w 2 8 100 I et:: / (./) l o 0 et:: 50 e-eSeadrift 0-0Blackjack A-A Indian Point ~ ~ 0 L-.L~-.=-.~..L......l.-L..L.....l---1.3111L=i~~1-L_J_.J........L_,L_~~~lllE..J-...L_J'---l........I MAMJJASONDJFMAMJJASONDJFMAMJJASO 1987 1988 1989 Ruppia maritima shallow (0.3 m) I 0 Ruppia maritima shallow (0.3 m) T l~ T ' 0 ·==o, tii~ Ruppia maritima. Above-and below-ground biomass at Seadrift, Blackjack and Indian Point. I I I I I I I r-"'.. N I I E I (/) <{ I 2 0 I rn I I I I I Figure 6. I I e-eIndian Pt. (0.3 m) 0-0Indian Pt. (0.6 m) 80 Halodule wrightii A-AE. Flats (0.4 m) T A 60 l .i~; m 5 ·-l • • ~40~r 0---?~. A 0 20 l~l 0 l A o.__..__...__...._~_.__..__.__.___..__.__.____..___...__.___.-----"~ 0 N D J F M A M J J A S 0 N D J F M 300 Halodule wrightii 250 I U) 0w 200 2 0 l T N I 150 0::: 0 U) l " b 100 l 0 0::: 50 0 _______ _.__.___.~..___.__.__.____.____..__....__.__,__,___._____. 0 N D J F M A M J J A S 0 N D J F M 1987 1988 Halodule wrightii. Above-and below-ground biomass at Indian Point and East Flats. I I 17 Table 1. Summary of the results of regression analyses between Ruppia maritimaI production (dependent variable) and salinity; temperature, and ambient DIN. ns: regression coefficient (r) is not significant. n = 8 to 18. I I Ruppia Shoot Production Parameter Seadrift Indian Point Salinity ns nsI Temperature ns p < 0.05 Ambient DIN ns ns I I I I I I I I I I I I I I 18 between water temperature and R. maritima growth at Indian Point. The absence of a I significant correlation between growth and DIN and between growth and salinity reflects I the generally inconsistent relationship between these parameters as depicted in Figures 2 and 3 for R maritima and in Figure 3 for Halodule wrightii. I Algal epiphyte biomass I Macroalgal and microalgal epiphytes on Ruppia maritima and Halodule wrightii I contributed a significant fraction of the total macrophyte biomass at all sites (Fig. 7). Algal epiphytes colonized the blades readily, and their biomass usually equalled or I exceeded that of the seagrasses themselves. At Seadrift, the algal epiphytes coalesced to I form a floating mat in autumn. In this instance, all the plant and algal material harvested within 0.10 m2 quadrats was used to estimate the percentage epiphyte fraction. Algal 2 I biomass in early autumn ranged from 74 to 79 g dry wt m·(1988, 1989) to over 200 in I 1987. The species composition of the algae differed significantly between sites (Table 2). I In San Antonio Bay (Seadrift and Blackjack), the epiphytic species included only greenI algae (Cladophora and Enteromorpha) and diatoms. In contrast, the algal epiphytes at Indian Point and East Flats in Corpus Christi Bay were chiefly composed of red algae (Polysiphonia and Graci/aria). Green algae were noticeably absent. I I I I I I I I I I I I I I I I I I I I I 1.0 SHALLOW (0.3 m) • •-•Seadrift 0-0Blackjack +-+Indian Point 0.8 T 0.6 0.4 ----0 0.2 0.0 L-..J'----1~~4-4--+-L----L.-J-----L.----L-----L-----1-----'--'-----4t~-'---~_,__,_-L-_.____, N D J F M A M J J A S 0 N D J F M A M J J A S 0 N 1.0 DEEP (0.4 m) •-•Seadrift 0-0Blackjack 0.8 0 0.6 o~f•! 0.4 0.2 0.0 "-".____.._..~L.t-f--+-'"---L---"---'---'--f-+--'---'--i----'"-ff--_,__,.......,.__.___,__,___.__. N D J F M A M J J A S 0 N D J F M A M J J A S 0 N 1986 1987 The overall contribution of algal epiphytes to total biomass at Seadrift, Blackjack and Indian Point. z 0 J u~ <( ..µ ~ ~ l.J_ c 5:w --0 I o o_ 0 o_ ..µ W'Q _J ~ <( '-' _J <( Figure 7. I 20 Table 2. Algal epiphyte species composition on Ruppia maritima and Halodule wrightiiI at Seadrift and Blackjack in San Antoiiio Bay and Indian Point and East Flats in Corpus Christi Bay. I I I San Antonio Bay I *Cladophora I Oedogonium *Enteromorpha I Microcoleus lyngbyaceus I Acrochaetium ALGAL EPIPHYfE SPECIES COMPOSITION Corpus Christi Bay *Polysiphonia *Graci/aria cylindrica Myriotrichia subcorymbosa Stictyosiphon subsimplex Diatoms I *Diatom5 (Bacillaria, Nitzschia, N avicula Synedra, Fragilaria) Chaetomorpha linum I *predominant species I I I I I I I 21 Drift macroalgal biomass I I The abundance of unattached (drift) macroalgae at two sites in Corpus Christi Bay is shown in Table 3. Seven species of drift algae were .harvested, and their abundance 2 I I varied from 0.1to4.9 g dry wt m-• Of the seven species, Dictyota dichotoma and Corallina cubensis were the least abundant. The largest percentage of the total biomass was I collected in water depths ranging from 49 to 53 cm, which was dominated by Thalassia I testudinum or Syringodium filiforme. Macroalgal biomass was greatest in Thalassia beds at both sites; 42% at East Flats and 49% at Fin and Feather, compared to about 29% and 39% in Syringodium beds and 29% and 12% in Halodule wrightii beds respectively. AlgalI diversity was also greatest within the Syringodium and Thalassia beds at each site. I In situ irradiance I I The results of continuous measurement of in situ irradiance at Indian Point and I Seadrift between March and June 1988 are shown in Figure 8. Photosynthetically active I radiation (PAR) varied considerably on a daily basis at both sites, but was noticeably higher at Indian Point than at Seadrift. The large variations in photon flux fluence rate I 2 (PFFR) was due to cloud cover, water turbidity, and water depth. The amount of water I covering the sensor is probably the largest factor, as measurements above 2000 µmol ms_, are undoubtedly caused by sensor exposure to direct sunlight at lower water levels. I I Table 3. Species composition and biomass of drift algae at East Flats (EF) and Fin and Feather (FF) within different seagrass beds at each site. Values are x ..±, SD (n = 10). Seagrass Bed Algal Biomass (g dry wt m·2) Algal species Syringodium ; Thalassia H alodule EF FF EF FF EF FF Gracilaria debilis 0.30±.0.18 2.67±.2.34 0.30±.0.10 4.08±.2.24 2.90±.1.50 1.05±.0.77 GraciZaria verrucosa 0.91±.0.45 0.88.±.0.38 0.21±.0.32 0.88±.0.83 lA1±.0.23 0.40.±.0.23 Gracilaria foliifera 1.80±.1.21 1.71.±.1.30 0.94±.0.77 Laurencia poitei 2.10±_3.00 0.69.±.0.82 0.93±.1.10 1.82±.3.02 0.91.±.0.10 0.09±.0.20 Corallina cubensis* 0.30±.0.25 -0.60±.1.00 1.36±.1.70 -0.65±.0.90 Digenia simplex -0.25±.0.19 4.S8±.2.45 0.34±.0.09 Dictyota dichotoma -0.63±.0.18 Total 5.4 6.8 7.9 8.5 5.2 2.2 *identification uncertain; may be Jania capillacea N N I I I 23 A comparison of the light regimes at Seadrift, East Flats and Indian Point over two I common time periods is shown in Table 4. Incident light data recorded at East Flats was I used in calculating percent light transmission at Indian Point since these sites were only separated by a few miles. Measurement of incident PFFR at Seadrift and Indian Point did not reveal any significant differences between the two sites (P = 0.61) in either of the I two three-month time periods. However, underwater PFFR varied significantly among sites. For the period 22 March to 20 June 1988, percent light transmission (% m-) was I 1 highest at East Flats (48.4% m-1), lowest at Seadrift (0.7% m-1), with Indian Point (21.5% I m-1) nearly intermediate between these two extremes. For the period 22 September to 19 December 1988, water transparency at Seadrift was significantly lower (P <0.0001) than at I East Flats. I I attribute the abnormally high spring 1988 values of PFFR and light transmission at I I East Flats (48.4% m-1) to the exposure of the quantum sensor to direct sunlight (for which it is not calibrated) during periods of low water, which occurred frequently during the daylight hours in spring. At Seadrift, we did not observe such large changes in water level, although the average water depth of the sensors at both sites was nearly the same (0.4 m). 1 I During the autumn, the percent light transmission at East Flats was 11% m-, compared to only 1 % m-at Seadrift. At Indian Point, the greater depth of the sensor (0.6 m) prevented I 1 its exposure to direct sunlight and therefore abnormally high values of PFFR were not I recorded. I I I I 24 2500 I INDIAN POINT 2000 I I 1500 I 1000 500 I u w z I <( o'r""" <( I n::: ~ May June 0::: IE I 2 0 :=J E 2500 SEADRIFT I ~ :l <( ~ 2000 I I 1500 I 1000 I 500 Missing data 0 -il--.1:.WUWJ.U.UUIJl.A.lJ.IJ I Mar 1 April June I 1988 Figure 8. Underwater quantum irradiance at the deepest levels of seagrass penetration at Seadrift (SD) in San Antonio Bay and Indian Point (IP) in Corpus ChristiI Bay over a 3-month period in 1988. Measurements were made once a minute and integrated hourly. I I I 25 Table 4. Comparison of the extinction coefficient (K), percent light transmission, and I I surface and underwater photon flux fluence rate (PFFR) at three sites, East Flats and Indian Point (Corpus Christi Bay) and Seadrift (San Antonio Bay). nd = no data. Seadrift (0.4 m) Indian Point (0.6 m) East Flats (0.4 m)Time Period K % m·1 K % m·1 K % m·1 I 22 March --5.01 0.7 -1.54 21.5 -0.72 48.4I 20 June '88 (n = 1698) I Average PFFR (µE m·2 s·1) Surface 491.6 nd 504.0 Underwater 66.2 200.1 377.1 I I 22 Sept. --4.57 1.0 nd nd -2.21 11.0 19 Dec. '88 (n = 702) I Average PFFR (µE m·2 s·1) Surface 349.5 nd 363.2 Underwater 56.3 nd 150.0 I I I· I I I I I I 26 DISCUSSION I Ovenvintering populations I • The seasonal growth dynamics of R maritima were strongly influenced by the presence I of an overwintering vegetative population. At Seadrift, no plants survived through the 1987I 1988 or 1988-1989 winter into early spring, as reflected in above and below ground biomass indices. As a result, all new growth at Seadrift arose from seeds buried in the sediment, I and a mature community did not develop there until late summer in both 1988 and 1989. I At Indian Point, Ruppia maritima appears to overwinter and persist throughout the winter and early spring. In 1988 and 1989 maximum development of the plants occurred I by mid May, followed by flowering and complete senescence by late August. In contrast, I large temporal variation in vegetative development occurred at Seadrift and Blackjack. In 1987 we noted that R maritima production and biomass were greatest in the late spring at I Blackjack and again in the late summer at both sites, with new growth originating from I both surviving patches of overwintering plants and from seed reserves in the sediment. Flowering thus occurred twice in 1987 at Blackjack and Seadrift, once in June at Blackjack, and again in late September at both sites. In 1988, flowering occurred in May at Indian I Point, June at Blackjack, and August at Seadrift. In 1989, flowering occurred by early June at Indian Point. At Seadrift flowering occurred by mid August in shallow (0.3 m) areas, and I in mid September in the deeper areas (0.4 m). R maritima flowered prolifically at these I times and at peak shoot density, most of the shoots were reproductive. Flowering shoots matured rapidly and all were lost along with the few remaining vegetative shoots, usually I I I I 27 about 4 to 5 months after germination or about 3 months after the onset of rapid growth I for overwintering plants. A sparse cover of new young shoots often appeared after flowering from the old rhizomes, sometimes persisting through the winter into the following I year at Indian Point and Blackjack. I For Ruppia maritima, the pattern of seed germination, shoot growth, rhizome I I development, flowering and senescence observed throughout this study is not one employed by Halodule wrightii. Instead, seasonal development and production in H wrightii is initially supported from a substantially larger root-rhizome complex that persists throughout the I year in this perennial plant. The different strategies of growth and production employedI by these two species may be interpreted in terms of r-and K-selection (MacArthur, 1962; MacArthur and Wilson, 1967). For R maritima, these results are consistent with those reported for the monocarpic reproductive pattern described by Brock (1983) for annual I species of Ruppia --rapid development of the plants, early maturity, and a large amount I of energy allocated to the production of a large amount of small propagules. I The existence of overwintering shoots of Ruppia maritima at Indian Point compared I to the absence or low abundance of overwintering plants at Seadrift and Blackjack may be related to lower wave exposure at Indian Point. The substantially higher degree of exposure at Seadrift and Blackjack can adversely affect these plants through physical disturbance of I root-rhizome complexes and the reduction of light. The effects of storms and waves on I populations of Ruppia spp. have been well documented (Verhoeven, 1979; Harrison, 1982). Our hypothesis that exposure to wind and wave action may influence the stability and I survival of established populations of R maritima is supported by observations and data that: (a) following stormy periods, roots and rhizomes became exposed on the sediment I I I I 28 surface and many plants were found as drift on the beach; {b) levels of PAR were I significantly lower at Seadrift, an exposed site, than at Indian Point, which is relatively protected from turbulent wave action; ( c) at Blackjack, the passage of barge and ship traffic I created large standing waves that either buried plants or eroded root systems; and ( d) large I overwintering populations of R mari.tima were present immediately adjacent to the I Blackjack site in a protected cove. I The clear absence of an overwintering population of Ruppia maritima in 1987-1988 and 1988-1989 at Seadrift may be related to the heavy fouling of the shoots by algal epiphytes. The plants at Seadrift were heavily laden by thick mats of Enteromorpha and I I Cladophora in the autumn of 1987, 1988 and 1989. The biomass of these mats was double that of the R maritima shoots and rhizomes and probably attenuated light penetration to I newly forming shoots considerably. In contrast, epiphyte loads were not as heavy or as I pronounced at Blackjack where populations of R. maritima overwintered in 1986-1987 and 1987-1988. I Drift Macroalgae and Epiphytes I In contrast to algal epiphyte colonization on seagrass leaves, which appears nearly I uniform within a seagrass bed, drift algae accumulates in patches of varying density and size. The heterogeneity of drift algae accumulation suggest that it may be a random or I haphazard process which is influenced by tides, wind, current, and the unique blade I morphology characteristic of different seagrass species. I I I 29 Algal epiphytes and drift algae play an import~_nt role in seagrass communities. I They serve as a habitat and food source for many animals, and they release large amounts of dissolved organic compounds through blade leakage and decay. Epiphytes and drift algae I I can also reduce the amount of light available for seagrass photosynthesis. However, according to the data collected by Cowper (1978), large macroalgae accumulate mainly I over bare patches within seagrass beds. If so, drift algae may supplement productivity inI areas that are otherwise unproductive. Mann (1973) showed that seaweeds provide more detritus to ecosystems than do I vascular marine plants, because microbial decomposition occurs more readily in algae than I in seagrasses and higher plants. The detrital remnants of algal epiphytes and macroalgae also contribute to the food supply of larger grazers, including some species of fish. Mugi.l I cephalus, or "striped mullet", have pharyngeal filtering devices which allow them to filter I feed directly on detritus (Odum, 1970). A study of organic detritus in the stomachs of mullet in various habitats indicates that 23% of the mullet stomach contents from Thalassia beds is organic detritus (Odum, 1970). Moreover, this organic detritus consumption is I directly correlated with the amount of readily available, digestible algae. Thus, algal epiphytes and drift algae may provide both detrital and macroscopic food supplies for I mullet and similar organisms. Algae also produce large pools of dissolved organic carbon I (DOC). Previous studies have shown that the average release of DOC relative to gross production is -39% for brown algae, -38% for red algae, and -23% for green algae. I From this data, Khailov and Burlakova (1969) concluded that excretion of DOM is a I significant factor in the energy budget of seaweeds and may be an essential carbon source to the inshore community. I I I I 30 I Growth and production dynamics I The high variation observed here with respect to the production and biomass of I Halodule wrightii and Ruppia maritima among sites and between seasons and years has I been reported earlier by several authors (Congdon & McComb, 1979; Pulich, 1985; FloresI Verdugo et al, 1988). Both Harrison (1982) and Flores-Verdugo et al. (1988) reported R maritima as an opportunist, yearly colonizing bare areas and having a growth cycle of four I months, during which the plants grew, branched, flowered and set seed. Harrison (1982)I found that seedling success fluctuated from year to year, especially in response to variations in weather in early spring when germination and establishment occurred. In this study, we I found that R. maritima completed its growth cycle over a period ranging from 3 to 5 I months. Higher exposure of Seadrift and Blackjack to wave disturbance and overgrowth of blades by epiphytic algae are the most logical explanations for the annual variations in R maritima biomass and the time of population maturation. I I The large seasonal variation in the timing of Ruppia maritima population maturity, as reflected in the time of flowering, reflects the opportunistic nature of this species. We found R maritima flowering as early as May and as late as October at the various study I sites. Often, different populations would develop at different rates, and flowering would occur twice within the same year at the same site. For example, overwintering plants in I deep water at Blackjack flowered by early June, whereas plants that developed from seed I in shallower water flowered in late September. The seasonal variation in the prolific I I I 31I flowering of R maritima allows it to maintain a large seed reserve in the sediment which is reflected in its opportunistic strategy of colonization. Although we did not find consistent evidence that Ruppia maritima growth wasI significantly influenced by salinity or DIN, the highest growth rates of R maritima were I recorded in May 1987 at Seadrift and Blackjack when ambient DIN levels were I exceptionally high and daytime water levels lowest. R maritima can be cultured in an I uprooted, floating habitat (Thursby, 1984; Seeliger et al., 1984), attesting to its ability to assimilate nutrients from the water column through its leaves. Thursby (1984) found that growth in R maritima was saturated at about 100 µ mol 1-1 nitrate. At Seadrift, I concentrations greater than this were measured through the spring 1987; at Blackjack the spring 1987 maximum was about 25 µ mol 1-1. However, our observations also revealed I that light availability was greatest during late April and early May 1987 (due to lower I daytime tides). DIN limitation is probably very rare for this species in San Antonio and Corpus Christi Bays since large differences in DIN concentrations among all three sites I revealed no significant differences in linear growth rates among sites. The highest DIN I concentrations were recorded at Seadrift, where growth rates were slightly lower than at Indian Point. We attribute the higher growth at Indian Point to more favorable levels of I PAR. I The total maximum range in Ruppia maritima biomass ranged from 0 to 330 g dry wt I m·2 during the two year study. Generally, biomass peaks occurred either in late springI and/or late autumn at the various sites depending on environmental conditions. The biomass values for R maritima are in the range reported for other areas of the world for R maritima (Table 5). Few studies have addressed the productivity and biomass of I I I I 32 I Halodule wrightii, but the biomass estimates reported here agree with published values I (Table 6). Root-shoot ratios (RSR) differed considerably between the two species, averaging 1.6 for Ruppia maritima and 3.0 for Halodule wrightii. The lower RSR ratio for R maritima is I consistent with that noted in other submerged freshwater and brackish aquatic plants in their non-dependence on asexual reproduction and in their preferred uptake of DIN I through leaves instead of roots (Stevenson, 1988). Lukatelich et al. (1987) found a lack I of obvious trends in RSR and no evidence that rhizomes in R megacarpa were important in providing reserves for maintenance of shoot production in nutrient saturated systems. I I The difference in RSR ratios between Ruppia and Halodule may also be a function of sediment organic content (Pulich, 1989). I It has long been recognized that algal epiphytes play an extremely important role in I seagrass ecosystems (Penhale, 1977; Heijs, 1984; Morgan and Kitting, 1984; Borum, 1987). Their biomass and productivity often match that of the seagrasses themselves (Table 7). I At Seadrift, the rapid autumn decline of Ruppia maritima is correlated with an annual peak I in epiphyte biomass. Shading of underlying leaves by epiphytes has been regarded as a major mechanism that retards seagrass growth (Sand-Jensen, 1977; Rice et al., 1983; Short I and Short, 1984). In addition, several authors (Larkum, 1976; Kemp et al., 1983; Cambridge I and McComb, 1984; Short and Short, 1984) have related major declines in the abundance of seagrasses to nutrient regimes which clearly benefited the rapid growth of epiphytes. As a consequence, any short term beneficial effect resulting from increased algal production I is balanced in the long term by the elimination of the epiphyte's major substratum. I I I 33 Table 5. Ruppia maritima. Total biomass of plants surveyed in temperate and tropical I regions. I I I Location I Pacific Coast, Mexico I Blackwood Estuary, Australia New South Wales, Australia I N aeria Strand, Denmark I Rinkobing Fjord, Denmark Robert Banks, British Columbia I Narragansett Bay, RI I Western Europe I San Antonio and Corpus Christi Bays, TX I *shoots only I I I SEAGRASS BIOMASS Ruppia maritima Total Maximum Biomass g dry wt m·2 620 503 600 243 17-28 4* 50-1,480 50-288 260-330 Reference Flores-Verdugo et al. (1988) Congdom and McComb (1979) Higginson (1968) Grontved (1958) Kiorboe (1980) Harrison (1982) Nixon and Oviatt (1973) Verhoeven (1980) This study I I 34 Table 6. Halodule wrightii. Total biomass of plants smveyed in temperate regions. I SEAGRASS BIOMASS I H alodule wrightii I Location Maximum Biomass Reference g dry wt m·2 I Redfish Bay, TX 400 Pulich, 1985 I Redfish Bay, TX 450* Morgan and Kitting, 1984 I Corpus Christi Bay, TX 245 This study I Laguna Madre, TX 325 Next study I *shoots only I I I I I I I I I 35 I Table 7. The relative contribution of algal epiphytes to the total biomass and production in seagrass communities. I ALGAL EPIPHYTES I Location % of total % of total Reference biomass production I Newport Estuary, NC 24 20 Penhale, 1977 I New Guinea, West Pacific 35 Heijs, 1984 Denmark 35.7 50 Borum and Wium-Anderson,I 1980 New Guinea, West Pacific 18 16-33 Heijs, 1987 I Redfish Bay, TX 50 50 Morgan and Kitting, 1984 I San Antonio and Corpus Christi Bays, TX 30-80 This study I Laguna Madre, TX 15-27* Next study I *AFDW I I I I I I I 36 The results of this study indicate that large changes in salinity and DIN, as brought I about by changes in freshwater inflow, have little direct effect on the growth dynamics of a euryhaline macrophyte species, Ruppia maritima. Although the persistence of lower I salinity water in San Antonio Bay prevented the invasion of truly marine angiosperms such I as Halodule wrightii in San Antonio Bay, the indirect effects of increased nutrient loading, which promotes rapid growth of macrophytic algae, may also cause a significant reduction I in the growth of R maritima. In extreme cases where levels of DIN remain elevated and I water transparency is low, opportunistic annuals such as R maritima may be unable to I become established, even for the short period necessary to complete their short life cycle.I As a result, the overall carbon contributionby macrophytes in nutrient laden estuarine systems may be drastically reduced or eliminated entirely. I Annual carbon and nitrogen budgets I I It has been long recognized that algal epiphytes play an extremely important role in I seagrass ecosystems (Penhale, 1977; Heijs, 1984; Morgan and Kitting, 1984). Their biomass and production often match that of the seagrasses themselves (Table 7). As a consequence, I their overall contribution to the carbon and nitrogen balance in estuarine systems should I not be overlooked. A summary of the contribution of both seagrasses and algal epiphytes to the nitrogen and carbon balances in San Antonio and Corpus Christi Bays is shown in Table 8. This budget is based on our observations that Ruppia maritima and Halodule I wrightii constitute the majority of the total seagrass biomass in San Antonio and Corpus Christi Bay respectively. Estimates of shoot turnover (P:B ratios) ranged from 3.1 for R. I I I 37 Table 8. A summary of the contribution of seagrasses and algal epiphytes to the carbonI and nitrogen balances in San Antonio and Corpus Christi Bay. nd = no data. I MACROPHYfE VITAL STATISTICS I I Average spring PFFR (at deepest depth of seagrass penetration, I µE m-2 s-1) Areal cover (m2) I Average annual biomass (g dry wt m-2) I shoots roots/rhizomes I I Shoot production (g dry wt m-2) (g C m-2 yr-1) Shoot turnover (yr-1) I I Nitrogen demand (seagrass) (g m-2 yr-1) (g yr-1) Epiphyte biomass (g dry wt m-2)I (g C m-2) I Macroalgal biomass (maximum) (g dry wt m-2) (g C m-2) I Total macrophyte production1 1 (g C m-2 yr-) I San Antonio Bay Corpus Christi Bay (Ruppia maritima) (Halodule wrightii) 66 200 13,505 30,985 15.2 35.9 23.7 108.5 47.1 260.8 16.5 91.3 3.1 7.3 0.8 4.5 11,140 141,367 13.5 31.1 4.7 10.9 nd 7.2 nd 2.5 38 151 1Based on a P:B ratio of 4.5 for epiphytes and a P:B ratio of 4.4 for drift macroalgae (see discussion). I I I 38 maritima in San Antonio Bay to 7.3 for H. wrightii in Corpus Christi Bay based on our I seasonal measurements of biomass and production. Our P:B estimate of 7.3 for H. wrightii I agrees with the value of 9.7 obtained by Morgan and Kitting (1984) for this species at an adjacent site in Aransas Bay. For R maritima, Kiorboe (1980) found P:B ratios to range 2 1 from 1.2 to 2.0 and shoot production to range from a high of 57 g dry wt m-yr-in I epiphyte-free populations to a low of 12 g dry wt m-2 yr-1 in R maritima subjected to heavy epiphyte fouling. Production estimates obtained in this study for R maritima (4 7 g dry wt I 2 1 m-yr-) fall within this range. Turnover rates were not calculated for epiphytes in this I study, but as a conservative estimate, a P:B ratio of 4 to 5 has been reported in the literature (Borum, 1987). Rates of production in marine macroalgae averaged about 2.0 I mg C g dry wt hr-1 in three species analyzed in Laguna Madre (Jania, Gracilaria, Laurencia; I Dunton, unpublished data). Based on this measurement, and assuming that these plants are I I light saturated an average of six hours day-1, a P:B ratio of 4.4 is obtained for drift macroalgae, similar to that reported for algal epiphyte turnover. Root-shoot ratios (RSR) differed considerably between the two species, averaging 1.6 I for Ruppia maritima and 3.0 for Halodule wrightii. The lower RSR ratio for R maritima isI consistent with that noted in other submerged freshwater and brackish aquatic plants in their non-dependence on asexual reproduction and ability for preferred uptake of DIN I -through leaves instead of roots (Stevenson, 1988). Lukatelich et al. (1987) also found no I obvious trends in RSR nor any evidence that rhizomes were important in providing reserves for maintenance of shoot production in nutrient saturated systems. Estimates of nitrogen demand for Ruppia maritima and Halodule wrightii are based on I literature values for Thalassia testudinum (Patriquin, 1972) and Zostera marina (McRoy and I I I I 39 McMillan, 1977) since such data is unavailable for either R. maritima or H. wrightii. Carbon I content of seagrass blades averages 38% (McRoy and McMillan, 1977; Aioi and Mukai, 1980) and is used in estimating the total macrophyte production in each bay (the carbon I content in macroalgae also lies in the range of 35 to 40%; Dunton and Schell, 1986). The I total contnbution by macrophytes on a 2 mbasis is nearly five times greater in Corpus I Christi Bay than in San Antonio Bay. This is attributed both to the higher biomass andI higher productivity of macrophytes in Corpus Christi Bay. Based on available data and the results of this study, our results indicate that large changes in salinity and DIN, as brought about by changes in fresh water inflow, have little I effect on the growth of a euryhaline macrophyte species, Ruppia maritima. I However, the question is best answered through in situ physiological experiments that address I photosynthetic and respiration parameters as a function of differing nutrient and salinity I indices. However, such experiments were unfortunately beyond the scope of this study. Although such an approach is not complex and would yield definitive results, the funds I allocated for this project were insufficient for physiological studies. Such work however, is I highly recommended and is necessary for a sufficient understanding of the importance of freshwater inflow to macrophyte production in Texas estuaries. This study sets the foundation for such work, as it has provided the first detailed information of the in situ I productivity of R. maritima over several seasons in two south Texas estuaries that differed according to their freshwater inflow regimes. I I I I I 40 I ACKNOWLEDGEMENTS I I gratefully thank the following people who assisted me in the field or in the I laboratory in various stages of this project which initially began under the direction of Dr. Warren Pulich: Julie and Butch Findley, Beau Hardegree, Suzanne Horner, Jeri Jewett I Smith, Pete Lawton, Todd Olson, Susan Schonberg and Barbara Smith. I I I ·· .:. I I I I I I I I I I I 41 LITERATURE CITED I Aioi, K. and H. Mukai. 1980. On the distribution of organic contents in the plant of eelgrass (Zostera marina L.). Jap. J. Ecol. 30:189-192. I Borum, J. and S. Wium-Andersen. 1980. Biomass production of epiphytes on eelgrass(Zostera marina L.) in the Oresund, Denmark. Ophelia, Suppl. 1:57-64. I I Borum, J., H. Kaas and S. Wium-Andersen. 1984. Biomass variation and autotrophicproduction of an epiphyte-macrophyte community in a coastal Danish area: 2. Epiphyte species composition, biomass and production. Ophelia 23:165-179. Borum, J. 1987. Dynamics of epiphyton on eelgrass (Zostera marina L.) leaves: relative roles of algal growth, herbivory and substratum turnover. Limnol. Oceanogr.I 32(4 ):986-992. Brock, M.A. 1983. Reproductive allocation in annual and perennial species of the I submerged aquatic halophyte Ruppia. J. Ecol. 71:811-818. Cambridge, M.L. and A.J. McComb. 1984. The loss of seagrasses in Cockburn Sound,I Western Australia. I. The time course and magnitude of seagrass decline in relation to industrial development. Aquat. Bot. 20:229-243. I Congdon, R.A. and A. J. McComb. 1979. Productivity of Ruppia: seasonal changes and dependence on light in an Australian estuary. Aquat. Bot. 6:121-132. I Cowper, S.W. 1978. The drift algae community of seagrass beds in Redfish Bay, Texas. Contrib. Mar. 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I Heijs, F.M.L. 1987. Qualitative and quantitative aspects of the epiphytic component in a mixed seagrass meadow from Papua, New Guinea. Aquat. Bot. 27:363-383. I Higginson, F.R. 1968. The ecology of submerged aquatic angiosperms within the Tuggerah Lakes system of New South Wales. Ph.D. Thesis, Univ. Sydney. I Irby, H.D.1973. Vegetation and wildlife. In, Environmental Impact Assessment of Shell Dredging in San Antonio Bay, Texas. Vol. V of V, App. C3-B. .Texas A&M Research Foundation, Galveston, pp. 109-113. I I Kemp, W.M., R.R. Twilley, J.C. Stevenson, W.R. Boynton and J.C. Means. 1983. The decline of submerged vascular plants in upper Chesapeake Bay: summary of results concerning possible causes. Marine Technol. Soc. J. 17:78-89. Khailov, K.M. and Z.P. Burlakova. 1969. Release of DOM by marine seaweeds and distribution of their total organic production to inshore communities. Limnol.I Oceanogr. 14:521-527. Kiorboe, T. 1980. 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Mem. 1st Ital. Idrobiol. Suppl. 29: 13-16. Pallanzo. I Mann, K.H. 1973. Seaweeds: their productivity and strategy for growth. Science 182:975 981. I I 43 McMillan, C. and R.C. Phillips. 1979. Differentiation in habitat response amongI populations of New World seagrasses. Aquat. Bot. 7:185-196. McRoy, C.P. and C. McMillan. 1977. Production ecology and physiology of seagrasses, p.I 53-81. In C.P. McRoy and C. Helfferich [eds.], Seagrass ecosystems: a scientific perspective. Dekker, New York. I Morgan, M.D. and C.L. Kitting. 1984. Productivity and utilization of the seagrass Halodule wrightii and its attached epiphytes. Limnol. Oceanogr. 29: 1066-1076. Nixon, S.W. and C.A Oviatt. 1973. I Ecology of a New England salt marsh. Ecol. Monogr.43:463-498. I Odum, H.T. 1970. Utilization of the direct grazing and plant detritus food chains by theI striped mullet Mugil cephalus. In: Marine Food Chains. Univ. of Calif. Press, pp.222-240. I Patriquin, D.G. 1972. The origin of nitrogen and phosphorus for the growth of the marine angiosperm Thalassia testudinum. Mar. Biol. 15:35-46. I Penhale, P.A. 1977. Macrophyte-epiphyte biomass and productivity in an eelgrass (Zosteramarina L.) community. J. Exp. Mar. Biol. Ecol. 26:211-224. I Seasonal growth dynamics of Ruppia maritima L.s.I. and Halodule I Pulich, W.M. 1985. wrightii Ashers. in southern Texas and evaluation of sediment fertility status. Aquat. Bot. 23:53-66. I Pulich, W.M. 1989. Effects of rhizosphere macronutrients and sulfide levels on the growthphysiology of Halodule wrightii Aschers. and Ruppia maritima L.sl. J. Exp. Mar. Biol. Ecol. 127:69-80. Rice, J.D., R.P. Trocine and G.N. Wells. 1983. Factors influencing seagrass ecology in theI Indian River lagoon. Florida Sci. 46:276-286. Roman, C.T. and K.W. Able. 1988. Production ecology of eelgrass (Zostera marina L.) inI a Cape Cod salt marsh-estuarine system, Massachusetts. Aquat. Bot. 32:353-363. I Sand-Jensen, K. 1977. Effect of epiphytes on eelgrass photosynthesis. Aquat. Bot. 3:55 63. SAS Institute Inc. 1985. SAS/STAT Guide for personal computers, Version 6 Edition. SASI Institute Inc., Cary, N.C. Seeliger, U., C. Cordazzo, E.W. Koch. 1984. Germination and algae-free laboratory cultureI of Widgeon Grass, Ruppia maritima. Estuaries 7:176-178. I I 44 Short, F.T. and C.A. Short. 1984. The seagrass filter: purification of estuarine and coastal waters. I In: The Estuary as a Filter edited by V.S. Kennedy, Academic Press, New York, pp. 395-413. I Stevenson, J.C. 1988. Comparative ecology of submersed grass beds in freshwater, estuarine, and marine environments. Limnol. Oceanogr. 33(4, pt. 2):867-893. I Strickland, J.D.H. and T.R. Parsons. 1972. A practical handbook of seawater analysis, 2nd ed. Bull. Fish. Res. Bd. Can. 167:1-310. I Thursby, G.B. 1984. Nutritional requirements of the submerged angiosperm Ruppia maritima in an algal-free culture. Mar. Ecol. Prog. Ser. 16:45-50. Verhoeven, J.T.A. 1979. The ecology of Ruppia-dominated communities in Western I Europe. I. Distribution of Ruppia representative in relation to their autoecology. Aquat. Bot. 6:197-268. I Virnstein, R.W. 1982. Leaf growth of the seagrass (Halodule wrightii) photographically measured in situ. Aquat. Bot. 12:209-218. I Westlake, D.F. 1965. Some basic data for investigations of the productivity of aquatic macrophytes. Memorie Ist. ital. Idrobiol. Suppl. 18:229-248. I I I I I I I I I I I PART II APPENDIX I MACROPHYTE BIOMASS AND PRODUCTION I AND SURFACE AND UNDERWATER IRRADIANCE IN SAN ANTONIO AND CORPUS CHRISTI BAYS I I I I I I I I I I I I I I I I I ----~ 4 km I I I I I I <:)~ ··· .. · ·: . ·• ·.·. I I I MATAGORDA ISLAND I Distribution of seagrasses in San Antonio Bay. Data includes that of Irby (1973). I Ruppia maritima was the only species found during this study in 1987. I APPENDIX Figure l I I I I I I I I I I I I I I I I Distribution of seagrasses in Corpus Christi and Nueces I bays from limited aerial and ground based surveys in 1988. Halodule wrightii dominates in Corpus Christi Bay,and Ruppia maritima is the predominant species in Nueces I Bay. APPENDIX Figure 2 I PROCALI 1 of 4 01/10/89 I SEAGRASS PRODUCTIVITY PRODUCTIVITY SHOOT GROWTH SHOOT PRODUCTION I Sta Depth Start End I Day g/12/day SE n x Hfday SE n 19/day/sh SE n I BLACKJACK PENINSULA BP SHA A 04/07/87 04/22/87 15 0.5613 0.0514 3 4. 7790 0.8193 34 0.1295 0.0004 3 I BP BP BP SHA SHA SHA A 04/22/87 04/27/87 H 04/27/87 05/04/87 J 05/04/87 06/02/87 5 7 31 1.6380 0.5741 0.0370 0.3050 0.1620 0.0177 3 3 3 8.6260 6.6640 1.4'320 1.0030 (I, 289'3 0.1477 72 49 16 0.1798 0.0628 0.0351 0.0002 0.0002 0.0006 3 3 3 I BP BP BP SHA SHA SHA J J 0 06/02/87 06/19/87 06/19/87 07/13/87 07/13/87 10/14/87 17 25 20 (l, 0161 nd 0.3042 0.0085 nd 0.0639 'i L nd 3 0.5882 nd 1.5761 0.0898 nd 0.0799 3 nd 9(1 0.0617 nd 0.0315 0.0007 nd 0.0001 2 nd 3 BP SHA N 10/14/87 11/21/87 38 0.3300 0.0715 3 0.6279 0.0224 177 0.0095 0.0001 3 I BP BP SHA SHA F 11/21/87 02/16/BB A 02/16/88 04/02/88 67 46 nd 0.0053 nd 0.0032 nd 3 nd 0.1030 nd 0.0490 nd 19 nd 0.0052 nd 0.0001 nd 3 BP SHA A 04/02/88 04/14/88 12 nd nd nd nd nd nd nd nd nd I BP BP BP SHA SHA SHA A 04/14/88 04/26/88 H 04/26/88 05/10/88 J 05/10/88 06/01/88 12 14 22 0.169'3 0.1264 0.055'3 0.0418 0.0254 3 3 2.1538 1. 7690 1. '3026 0.1824 0.1602 (I, 368'3 78 60 7 0.0375 0.0390 0.0432 0.0001 0.0001 3 3 1 BP I BP BP SHA SHA SHA J 06/01/88 06/22/88 J 06/22/88 07/15/88 A 07/15/88 08/05/88 21 23 21 nd 0.5169 0.1469 nd 0.1191 0.0238 nd 3 3 nd 3.2'31'3 1. 4243 nd 0.1451 0.0742 nd 70 56 nd nd 0.136'3 0.000918 0.0486 0.000211 nd 3 3 BP SHA A 08/05/88 08/25/88 20 nd nd nd nd nd nd nd nd nd I BP BP SHA SHA S 08/25/88 09/21/88 0 09/21/88 10/12/88 27 21 0.1155 0.1313 0.0214 0.0503 3 3 1.4430 1.1576 0.0993 0.1000 77 7'3 0.0264 0.000178 0.0210 0.000221 3 ') ..J BP SHA N 10/12/88 11/11/88 30 0.0173 0.0000 3 0.8703 0.1000 17 0.0188 0.000066 3 BP I BP SHA DEEP D 11/11/88 12/19/88 A 04/07/87 04/22/87 38 15 nd 1. 6910 nd 0.1950 nd 3 nd 5.3770 nd 0.1636 nd 117 nd 0.1299 nd 0.0004 nd 3 BP I BP BP DEEP DEEP DEEP A 04/22/87 04/27/87 H 04/27 /87 05/(14/87 J 05/04/87 06/02/87 5 7 31 1. 8410 1.4710 0.3663 0.2564 0.2241 0.0833 3 3 3 8.8520 7.1340 2.4160 0.3004 0.2640 0.1089 82 73 48 0.1854 0.1756 0.0689 0.0001 0.0003 0.0006 3 3 3 BP DEEP J 06/02/87 06/19/87 17 0.0252 0.0043 2 1.0510 0.1601 8 0.0671 0.0003 2 I BP BP BP DEEP DEEP DEEP J 06/19/87 07/13/87 0 07/13/87 10/14/87 N 10/14/87 11/21/87 25 20 38 nd 0.6473 0.1452 nd 0.0364 0.0098 nd 3 3 nd 2.5008 0.5502 nd 0.1076 0.0254 nd 96 98 nd 0.0411 0.0083 nd 0.0001 0.0001 nd 3 3 BPI BP BP DEEP DEEP DEEP F 11/21/87 02/16/88 A 02/16/88 04/02/88 A 04/02/BB 04/14/88 67 46 12 0.0365 o. 327·3 0.0742 0.0051 0.2220 0.0162 3 3 3 0.1846 0. 535•3 1. 3810 0.0161 0.0338 0.1133 90 86 70 0.0035 0.0~84 0.0162 0.0000 0.0019 0.0001 3 3 3 BP I BP BP DEEP DEEP DEEP A 04/14/88 04/26/88 H 04/26/88 05/10/88 J 05/10/BB 06/01/88 12 14 22 0.1740 0.3764 0.1123 0.0337 0.1323 0.0662 3 3 3 2.1135 2.%14 1. '342'3 0.1529 (l.1467 0.1200 8(1 74 39 0.0389 0.0001 0.0572 0.0004 0.0534 0.000879 3 3 3 BP DEEP J 06/01/88 06/22/88 21 (I, 4410 0.0764 2.3133 0.1067 89 0.0743 0.000353 3 I BF BP BP DEEP DEEP DEEP J 06/22/88 07/15/88 A 07/15/88 08/05/88 A 08/05/88 08/25/88 23 21 20 0.2%2 0.1307 0.3768 0.1434 0.0319 0.0326 3 2.7065 1.1179 2.0280 0.1465 0.0881 0.0835 47 65 90 0.1168 0.001574 0.0373 0.000204 0.0499 0.000126 3 3 ·3 BP I BP BP DEEP DEEP DEEP S 08/25/88 09/21/88 0 09/21/88 10/12/88 N 10/12/88 11/11/88 27 21 3(1 (l.3077 0.0814 0.2978 0.0707 0.0177 0.0756 3 3 1.6344 1.3848 1.1373 0.0856 0.1300 0.0750 90 49 90 0.0340 0.000267 0.0308 0.000144 0.0341 0.000297 3 3 3 BP DEEP D 11/11/88 12/19/88 38 0.0032 o. 001 '3 ·j i.. (I, 778'3 0.1524 5 0.007'3 0.000254 .-, L I PROCAL1 2 of 4 01/10/89 I SEAGRASS PRODUCTIVITY PRODUCTIVITY SHOOT GROWTH SHOOT PRODUCTION I Sta Depth Start End I Day g/m2/day SE n x 111/day SE n 119/day/sh SE n I SEADRIFT I SD SHA H 03/04/87 03/25/87 21 0.0547 0.0125 3 1.1990 0.0924 31 nd nd nd SD SHA A 04/07/87 04/22/87 15 0.0571 0.0072 3 1. 5610 0.3582 1'3 0.1433 0.0006 3 I SD SD SD SHA SHA SHA A 04/22/87 04/27/87 H 04/27/87 05/04/87 J 05/04/87 06/03/87 5 7 32 0.5257 0. 2728 nd 0.0070 0. 0745 nd 3 3 nd 6.7460 4.8510 nd 1.2320 0.9500 nd 30 26 nd 0.1304 0.0~50 nd 0.0000 0.0002 nd 3 3 nd SD SHA J 06/03/87 06/19/87 17 0.0152 0.0038 2 1.2280 0.2677 8 0.0500 0.0004 2 I I SD SD SD SD SD SHA SHA SHA SHA SHA J 06/19/87 07/13/87 0 07/13/87 10/14/87 N 10/14/87 11/21/87 F 11/21/87 02/22/88 H 02/22/88 03/29/88 25 20 38 93 36 0.0032 0.0081 0.0703 0.0012 0.0040 0.0032 0.0260 (l.0007 0.0013 1 3 3 3 3 1.1200 0.6383 0.6501 0.'1923 0.4405 o. 0611 0.1700 0.0467 0.0355 0.0748 3 15 81 17 21 0.0200 0.0100 0.0096 0.0013 0.0036 0.0002 0.0002 0.0001 0.0000 1 3 3 3 3 SD SHA A 03/29/88 04/14/88 16 0.0030 0. 0010 3 0.6641 0.0883 40 0.0014 0.0000 3 I SD SD SD SHA SHA SHA A J J 04/14/88 04/26/88 04/26/BB 06/02/88 06/02/88 06/23/88 · 12 37 21 0.0000 nd 0.0247 0.00(1(1 nd 0.0247 3 nd 2 0.7639 nd 0.6625 0.3459 nd 0.0977 6 nd 34 0.0000 0.0000 nd nd 0. (1098 (I, (1(10282 3 nd ·i L. SO SHA J 06/23/88 07/11/88 24 (l.2821 (!.05(1(1 3 2.1884 0.0558 '3(1 0.0393 0.000294 3 I SD SO SD SHA SHA SHA A 07/11/88 08/04/98 A 08/04/88 08/25/88 S 08/25/88 09/12/88 23 22 19 0.3565 0.138(1 0.0724 (1,(1632 0.0207 0.0162 3 3 2.2700 1.8421 1.1421 0.0966 o. 091 '3 0.0775 90 74 90 0.0456 0.000344 0.0291 0.000187 0.0117 0.000057 3 3 3 I SD SD SD SHA SHA SHA 0 09/12/88 10/10/88 N 10/10/88 11/14/88 D 11/14/88 12/20/88 28 35 36 0.12(18 o. 0088 0. (101 '3 0.0263 0.0013 3 1 3 0.8471 0.5714 0.4981 0.07'33 0.0434 0.0775 90 3 16 0.0160 0.000113 0.0181 0.0023 0.000063 3 3 I SD SD DEEP DEEP H 03/04/87 03/25/87 A 04/07/87 04/22/87 21 15 (1.1135 0.5847 0.0129 0.3168 ") "' 3 1.5920 2.1230 0.1155 0.1279 30 45 0.0262 0.2269 0.0020 3 SD DEEP A 04/22/87 04/27/87 5 1. 8040 0.4677 3 6.7560 0.3058 42 0.3618 0.0006 3 I SD SD SD DEEP DEEP DEEP H 04/27/87 05/04/87 J 05/04/87 06/03/87 J 06/03/87 06/19/87 7 32 17 0.3421 0.0146 0.01'35 0.1009 0.0136 0.0176 3 ') L. .-, i. 4.7010 0.6562 1.2940 0.0437 0.1579 0.1608 35 7 6 0.0706 0. 0110 0.0441 0.0002 0.0006 0.0010 3 2 2 I SD SD SD DEEP DEEP DEEP J 06/19/87 07/13/87 0 07/13/87 10/14/87 N 10/14/87 11/21/87 25 20 38 nd (l, 7727 0.0541 nd 0.1125 0.0179 nd 3 3 nd 2.4117 0.3558 nd 0.1093 0.0302 nd 98 90 nd 0.0478 0.0045 nd 0.0002 0.0001 nd 3 3 SD DEEP F 11/21/87 02/22/88 •33 0.0017 0.0003 'i "' 0.2058 0.0277 21 0.0015 0.0000 3 I SD SD DEEP DEEP H 02/22/88 03/29/88 A 03/29/88 04/14/88 36 16 0.0020 0.0020 0.0011 0. 0010 ·i L 3 0.3981 0.8125 0.0334 0.1160 3 21 0.0083 0. 0018 0.0002 o. 0000 ,., L. 'i "' SD DEEP A 04/14/88 04/26/88 12 (I, 0013 0. 0001 1.6111 (l.3303 6 0.0028 0.0000 SDI SD DEEP DEEP J J 04/26/88 06/02/88 06/02/88 06/23/BB 37 21 0.0074 0.0781 0.0102 3 1.3063 1.3760 0.1345 o. 0751 3 77 0.0153 0.0172 0.000070 3 SD DEEP J 06/23/88 07/11/88 24 0.2412 0.0251 3 2.0167 0.0672 90 0.0389 0.000149 3 SD I SD SD DEEP DEEP DEEP A 07/11/88 08/04/88 A 08/04/88 08/25/88 5 08/25/88 09/12/88 23 22 1'3 0.6013 0.6218 (l, 5834 0.0469 0. 016'3 0.1165 3 3 1. 4769 1.5940 1. 6161 0.0668 0.0784 0.0851 130 145 150 0.0242 0.000095 0.0218 0.000039 0.0229 0.000122 3 3 3 SD DEEP 0 09/12/88 10/10/88 28 0.2871 0.0887 3 1. 5521 0.0679 95 0.0225 0.U00241 3 I I PROCAL1 3 of 4 I 01/10/89 SEAGRASS PRODUCTIVITY PRODUCTIVITY SHOOT GROWTH SHOOT PRODUCTIONg/m2/day ma/day 11g/day/sh I Sta Depth Start End I Day SE n x SE n SE n I SD DEEP N 10/10/88 11/14/88 35 0.1182 0.0113 3 0.6309 0.0314 90 0.0166 0.000108 3SD DEEP D 11/14/88 12/20/88 36 0.0155 0.0038 2 o. 73'32 o. 04'32 42 0.0068 0.000092 2 I EAST FLATS I I I EF HID D 11/04/87 12/07/87 33 0.1736 0.0015 3 0.9449 0.0538 90 0.0266 0.0001 3EF HID J 12/07/87 01/27/88 51 0.0308 0.0079 3 0.3137 0.0334 43 0.0133 0.0003 3EF HID M 01/27/88 03/24/88 57 0.1329 0.0091 3 0.7404 0.0362 90 0.0216 0.0002 3EF HID A 03/24/88 04/12/88 19 0.8586 0.0732 3 3.0924 0.1267 90 0.0910 0.6002 3EF HID A 04/12/88 04/28/BB 16 0.5209 0.0809 3 3.1047 0.1821 83 0.0818 0.0003 3EF HID H 04/28/88 05/17/88 19 nd nd nd nd nd nd nd nd ndEF HID J 05/17/88 06/03/88 12 0.5152 0.0543 3 5.8279 0.4104 61 0.1492 0.000296 3EF HID J 06/03/88 06/22/88 18 0.2712 0~0816 3 2.6754 0.2344 51 0.1006 0.000700 3I EF HID J 06/22/88 07I12/BB 23 0.3279 0.1636 3 2.4605 0.2973 27 0.2251 0.002998 3EF HID A 07/12/88 08/01/88 19 0.2232 0.0626 3 4.7000 0.3450 30 0.1379 0.000863 3EF HID A 08/01/88 08/22/88 21 0.0514 0.0076 3 2.3069 0.2776 18 0.0529 0.000196 3EF HID S 08/22/88 09/14/88 21 0.2466 0.0875 2.0338 0.1371 6'3 0.0586 0.000582 3EF MID 0 09/14/88 10/12/88 28 0.4356 0.0583 3 2.3304 0.0821 88 0.0769 0.000409 3EF HID N 10/12/88 11/11/88 30 0.3630 0.0438 3 1. '3533 0.0737 86 0.0740 0.000311 3I EF HID D 11/11/BB 12/19/BB 38 0.1711 0.0068 3 1. 3374 0.0388 89 0.0356 0.000056 3 I INDIAN POINT I I IP SHA D 10/21/87 12/08/87 48 0.2788 0.0320 3 1.2920 0.1034 71 0.0728 0.0005 3IP SHA J 12/08/87 01/25/88 31 0.1357 0.0157 3 0.6362 0.0526 86 0.0286 0.0001 3IP SHA H 01125/88 03/22/88 57 o. (1920 0. 0162 3 0.5457 0.0597 68 0.0251 0.0003 3IP SHA A 03/22/88 04/15/88 24 0.2785 0.0216 2.3001 0.1992 5'3 0.0890 0.0003 3IP SHA A 04/15/88 04/27/88 12 0.1699 o. 0701 3 3.3095 0.3815 35 0.0900 0.0007 3IP SHA H 04/27/88 05/12/88 15 o. 4578 0.1777 3 4.0041 o. 304'3 65 0.1102 0.0009 3IP SHA H 05/12/88 05/31/BB 13 0. 6195 o. 1311 3 5.7644 0.4667 48 0.2393 0.000948 3IP SHA J 05/31/88 06/20/88 21 0.7018 0.1809 3 6.0412 0.2353 67 0.1913 0.001281 3IP SHA J 06/20/BB 07/11/BB 21 0.5777 0.0507 3 4.7892 0.3541 54 0.1983 0.001454 3 ·j I.. ·I I IP SHA A 07/11/88 08/01/88 21 0.03'17 0.0035 l.'3870 0.4134 11 0.0446 0.000433 2IP SHA A 08/01/88 08/22/88 21 0.3013 0.0035 3 3.5034 0.2569 42 0.1330 0.000347 3IP SHA s 08/22/88 09/12/88 21 0.0891 0.0508 3 2.2103 0.3497 24 0.0688 0.001050 3IP SHA 0 09/12/BB 10/07/88 0.0602 0.0068 3 2.4908 0.5888 11 0. 1015 0.000966 3IP SHA N 10/07/88 11/14/88 38 (I, 2615 o. 08'37 3 2.2176 0.17.18 77 0.0557 0.000836 3IP SHA D 11/14/88 12/20/BB 36 0.0874 0.0213 3 1.1122 (l,(lf,5&· 68 0.0238 0.000305 3 I IP HID D 10/21/87 12/08/87 48 0.2411 0.0614 3 0.5242 0. 0284 '33 0.0165 0.0002 3 I IP HID J 12/08/87 01/25/88 . 31 0.1744 0.0397 3 0.4047 0.0205 147 0.0066 0.0001 3IP HID M 01/25/88 03/22/88 57 nd nd nd nd nd nd nd nd ndIP HID A 03/22/BB 04/15/88 24 0.3392 0.0249 3 1. 7'391 0.1177 90 0.0307 0.0001 3IP HID A 04/15/88 04/27/88 12 0.3574 0.0593 3 2.0069 0.1244 % 0.0236 0.0001 3IP HID M 04/27/88 05/12/88 15 0.3316 0.0447 3 1.8007 (1.09% 90 0.0301 0.0001 3 I I PROCALl 4 of 4 01/10/89 SEAGRASS PRODUCTIVITY I PRODUCTIVITY SHOOT GROWTH SHOOT PRODUCTION g/m2/day mm/day mg/day/sh I Sta Depth Start End I Day SE n SE n SE n I IP HID t1 05/12/88 05/31/88 13 0.2764 0.0836 3 2.4983 0.1308 90 0.0363 0.000153 3 ·j IP HID J 05/31/88 06/20/88 21 0.1245 0. (1'375 l. 3622 0.146'3 38 0.0366 0.000767 2 L IP MID J 06/20/88 07/11/88 21 0.1166 0.0540 3 2.4238 0.2466 30 0.0721 0.001024 3 'j IP HID A 07/11/88 08/01/88 21 0.0426 0.0178 1.8540 0.25% 15 0.0527 0.000723 3 I "' IP HID A 08/01/88 OB/22/88 21 0.0139 1.9524 0.8095 2 0.0429 'j IP HID s 08/22/88 09/12/88 21 0.0277 0.0038 0. 7677 0.1458 33 0.0156 0.000112 3 "' ')C' .., I L.JIP HID 0 09/12/88 10/07/88 0.0175 0.0097 3 0.6920 0.1436 13 0.0249 0.000369 .l IP HID N 10/07/88 11/14/88 38 nd nd nd nd nd nd nd nd nd .., IP MID D 11/14/88 12/20/88 36 0.0907 0.0127 3 0.9956 0.0374 76 0.0221 0.000184 .l I IP DEEP D 10/21/87 12/08/87 48 0.1757 0.0182 3 1.0468 0.05'30 9(1 0.0332 0.0002 3 IP DEEP J 12/08/87 01/25/88 31 0.1122 0.0151 3 0.6982 0.0359 90 0.0194 o. 0001 3 IP DEEP H 01/25/88 03/22/88 57 0.2368 0.0170 3 1.2535 0.0734 82 0.052'3 0.0003 3 IP DEEP A 03/22/88 04/15/88 24 0.6028 (1.0364 3 2.5417 0.0946 89 0.1106 0.0002 3I IP DEEP A 04/15/88 04/27/88 12 0.6"372 0.0432 3 3.3657 0.1676 '30 0.1197 (1.0002 3 IP DEEP M 04/27/88 05/12/88 15 0.2557 0.0403 3 2.1582 0.1447 59 0.0803 0.0003 'J "' 'j .., IP DEEP M 05/12/88 05/31/88 13 0.7535 o. 44'33 2. '3765 0.2213 72 0.1247 0.001200 "' "' .., .., IP DEEP J 05/31/88 06/20/88 21 0. 7241 o. 2'374 .l 2.9385 0.1853 72 0.1232 0.001449 ,j IP DEEP J 06/20/88 07/11/88 21 1.0935 0.0727 3.4740 0.1426 87 o. 2048 o. 0004 '30 I "' 'j .., 'j "' .., IP DEEP A 07/11/88 08/01/88 21 0.2158 0.0912 .) 2.2502 0.1164 51 0.0784 0.000933 ,j IP DEEP A 08/01/88 08/22/88 21 0.3501 0.0346 3 1.8800 0.0834 79 0.0792 0.000238 .., ,) I .., .., ,j IP DEEP s OB/22/88 09/12/88 21 0.2923 0.0425 .) 2.6273 0.1711 52 0.1042 0. (1(1(1439 '1 IP DEEP 0 09/12/88 10/07/88 25 0. 2773 0.0506 ,j 1.3848 (l,0'336 '30 0.0345 0.000233 3 ') '1 I ,j IP DEEP N 10/07/SB 11/14/88 38 0.4020 0.0555 .., 2.0600 0.1134 68 0.1021 0.001245 .., .., IP DEEP D 11/14/88 12/20/88 36 0.0'374 o. 0210 ,j 1.05(18 0.0817 73 0.0247 0.(10(1218 ,j I I I I I I I I BIOHASSl l of 4 10/17/89 I SEAGRASS BIOMASS STA DEPTH DATE OEN(x} DEN(SE) DEN(n) SH(x) SH SH(n} RR(x) RR(SE) RR(n} OET(x) OET(SE> OET(n} I (l/12) (l/12) BLACKJACK PENINSULA I BP Sha N 11/19/86 11490.00 1780.10 I BP Sha J 01/27/87 14726.50 BP Sha H 03/03/87 11570.90 2994.30 BP Sha A 04/07/87 8037.50 1484.20 BP Sha J 06/02/87 8107.90 2608.70 BP Sha J 07/13/87 485.50 247.20 BP Sha s 09/24i87 40835.10 4079.53I BP Sha f 02/16/88 12730.63 328.13 BP Sha H 05/10/88 12568.79 3448.58 BP Sha 0 10/12/88 9763.74 3291.87 I I BP Deep N 11/19/86 9233.90 1466.10 BP Deep J 01/27/87 16830.30 BP Deep/MM 03/03/87 6554.10 880.20 BP Deep A 04/07/87 14888.40 2189.20 BP Deep J 06/02/87 11191.60 763.20 BP Deep J 07/13/87 2373.50 460.90I BP Deep S 09/24/87 12730.63 1233.68 I BP Deep f 02/16/88 12838.51 328.13 BP Deep M 05/10/88 8684.BB 954.35 BP Deep 0 10/12/88 17315.81 1950.93 I SEADRIFT SD Sha N 11/19/86 10438.05 2346.50 SD Sha J 01/27/87 14241.00I SD Sha H 03/04/87 7606.00 1192.90 I SD Sha A 04/07/87 4908.80 328.10 SD Sha J 06/03/87 2211.70 636.00 SD Sha J 07/13/87 3182.70 1726.20 I SD Sha s 09/24/87 28482.08 6474.74 SD Sha f 02/22/88 755.21 377.61 SD Sha M 05/10/88 863.09 300.34 SD Sha 0 10/10/88 9062.48 2807.65 SD Hid N 11/19/86 9548.00 5664.10I SD Hid M 03/04/87 8577.00 SD l'lid J 06/03/87 4096.40 1133.50 SD Hid J 07/13/87 6257.40 1183.10 I SD Deep N 11/19/86 12461.00 809.10 SD Deep J 01/27/87 8577.00 I SD Deep M 03/04/87 19096.00 2173.20 SO Deep A 04/07/87 8792.80 2277.80 SD Deep J 06/03/87 4261.50 945.20 SD Deep J 07/13/97 2913.00 247.20 I 2 1 2 3 3 3 3 3 3 3 2 1 4 3 3 3 3 3 3 3 2 1 3 3 3 3 3 3 3 3 2 1 3 3 2 3 3 3 3 (g/12) 37.02 20.16 8.34 24.45 49.65 0.48 218.67 9.95 19.00 20.49 21.21 26.57 8.43 33.96 59.28 4.30 29.59 11.04 27.60 54.20 20.30 9.81 2.95 3.61 5.11 8.35 108.61 0.24 0.43 17.18 22.57 2.75 18.68 15.51 22.57 4.85 9.67 3.37 1.95 3.17 (g/12} 2.23 3.57 4.31 12.08 0.24 25.77 0.24 4.61 6.89 1.01 0.84 7.07 8.77 0.70 1.25 1.58 3.33 5.82 5.17 0.14 0.94 1.14 4.31 21.99 0.12 0.09 6.61 4.72 3.59 3.04 7.43 1.03 1.24 0.73 0.65 (g/112} (g/1112) (g/112} (g/12) 2 22.52 2.83 2 3.48 1 32.17 1 5.44 1 2 14.75 6.56 2 1.20 0.68 2 3 10.28 3.45 3 0.80 0.37 3 3 19.38 3.27 3 0.31 0.21 3 3.23 1.41 3 0.98 0.19 3 3 109.06 10.06 3 3.77 1.92 3 3 53.94 2.52 3 8.63 2.74 3 3 20.91 6.25 3 9.24 . 2.01 3 3 26.22 9.50 3 1.73 1.06 3 2 22.38 0.44 2 5.17 0.25 2 1 26.28 7.01 4 8.83 1.86 4 4.64 2.02 4 3 18.79 3.50 3 3.69 1.19 3 3 23.83 3.64 3 3.13 0.63 3 3 18.00 1.81 3 4.87 1.21 3 3 32.26 5.37 3 1.10 0.31 3 3 42.14 3.08 3 9.19 1.73 3 15.03 1.43 3 2.49 0.57 3 3 50.56 7.20 3 2.97 0.73 3 2 19.48 9.06 2 6.76 1. 36 2 30.26 2.91 3 15.62 4.30 3.95 1. 48 3 3 8.68 1.37 3 4.15 0.59 3 3 2.07 0.66 3 0.24 0.14 3 3 1.96 0.91 3 0.59 0.13 3 3 51.07 9.23 3 1.09 0.31 3 3 4.31 2.85 3 8.58 1.60 3 3 0.59 0.18 3 1.02 0.65 3 3 85.48 24.40 3 1. 71 0.76 3 2 26.53 9.54 2 5.93 1.48 2 14.7'3 1 3. '38 1 3 0.00 0.00 0 0.00 0.00 (I 3 3.09 0.53 3 0.61 0.29 3 r, L 2 24.40 2.84 3.59 0.49 2 10.31 4.52 3 31.31 3.87 3 10.18 2.15 3 ..J 3 8.11 0.96 'j 8.08 2.44 3 3 3.03 0.47 3 0.67 0.22 3 3 2.33 0.32 3 1. 34 0.21 3 I I BIOl1ASS1 2 of 4 10/17/89 SEAGRASS BIOMASS STA DEPTH DATE DEN(x) DEN(SE) DEN(n) SH(x) SH(SE) SH(n) RR(x) RR(SE> RR(n) DET(x) DET(SE) DET(n) I (l/al2) (l/m2) (9/1i2) (g/m2) (9/112) (g/m2) (g/112) (g/112) ·1 SD Deep s 09/24/87 15697.51 1214.66 3 44.08 3.81 3 27.12 3.16 3 0.44 0.15 i.. SD Deep F 02/22/88 5771.94 607.93 3 1.95 0.24 3 36.57 5.49 3 25.02 8.22 3I SD Deep H 05/10/88 593.38 235.13 3 0.62 0.21 3 1. 90 1. 21 3 12.18 5.94 3 SD Deep 0 10/10/88 16344.83 2055.52 3 35.37 4.11 3 160.24 30.87 3 2.19 0.66 2 I TURNS TAKE I TS Sha N 11/19/86 15293.00 2022.80 2 18.40 0.83 2 40.27 2 'i'J 2 2.30 0.18 2 oL.J TS Sha J 01/27/87 2912.90 1 1. 4'3 1 7.95 1 14. 79 1 I TS Sha H 03/04/87 1078.90 235.20 3 1. 26 0.40 3 0.80 0.38 3 1.42 1. 22 3 TS Sha A 04/07/87 1024.90 460.90 3 0.78 0.31 3 1. 32 0.44 3 0.43 0.24 3 TS Sha J 07/13/87 2211.70 377.60 3 7.36 1.05 3 2.35 0.55 3 0.80 0.16 3 I TS Deep N 11/19/86 3855.90 1322.80 2 9.43 4.63 2 24.41 3.60 2 8.33 3.95 'i I.. TS Deep J 01/27/87 485.50 1 0.19 1 0.71 1 14.66 1 TS Deep H 03/04/87 4207.60 1468.40 · 3 6.16 2.00 3 29.81 13.39 3 5.14 3.12 3 TS Deep A 04/07/87 7228.40 656.30 3 11.59 4.91 3 16.75 8.00 3 18.46 1. 73 TS Deep J 06/03/87 6689.00 863.10 3 21.90 2.08 3 24.50 8.82 3 12.4(! 2.62I TS Deep J 07/13/87 9817.70 999.00 3 28.09 5.02 3 44.12 9.11 3 14.32 3.31 TS Deep s 09/24/87 20066.92 4139.72 3 122.88 27.82 3 81.98 26.11 '3, 34 1. 51 3 I EAST FLATS I EF Hid N 11/04/87 8091.50 901.06 3 24.14 10.50 3 205.00 25.62 3 127.71 5Q.59 3 ., EF Hid J 01/27/88 3398.43 428.17 3 7.74 1.19 3 73.32 14.3'3 3 157.34 19.25 J I EF Mid M 05/17/88 9386.14 1555.03 3 55.48 3.55 3 53.66 16.81 3 155.69 36.98 3 o,JEF Hid 0 10/12/88 7012.63 888.02 3 69.10 5.09 3 90.02 12.19 3 17.66 2.27 •j INDIAN POINT I I IP Sha 0 10/21/87 5556.16 1998.15 3 44.02 14.22 3 122.80 23.77 3 47.84 8.24 3 IP Sha J 01/25/88 7390.24 1160.76 3 41.36 7.40 3 135. 83 13. 64 3 56.75 7.11 3 IP Sha " 05/12/88 9709.80 1 50. 20 50.90 60.70 1 IP Sha 0 10/07/88 4099.69 725.73 3 47.72 8.96 3 83.41 19.28 3 44.83 13.00 3 I IP Hid 0 10/21/87 26108.57 755.23 3 176.03 13.21 3 85.21 1.90 3 77.62 37.28 3 IP Hid J 01/25/88 23842.95 907.49 72.44 4.18 3 100.58 5.82 3 41.14 15.44 3 IP Mid H 05/12/88 16992.15 1257.01 3 24.40 1.24 3 21.17 3.70 3 23.96 4.74 3 IP Hid 0 10/07/88 1618.30 948.24 3 30.89 26.67 3 8.7& 4.45 3 10. (!(l I IP Deep 0 10/21/87 4585.18 1082.94 3 33.86 0.90 3 110.BB 17.17 3 30.27 12.48 3 IP Deep J 01/25/88 4531.24 705.42 3 24.3& 7.29 3 99.69 12.39 3 16.77 6.65 3 IP Deep H 05/12/88 4423.35 300.34 3 30.34 2.03 3 66.86 6.85 3 32.70 6.04 3I IP Deep 0 10/07/88 6473.20 1298.01 3 35.49 3.67 3 209.32 56.12 3 39.76 10.82 3 I I Bl011ASS1 3 of 4 I 10/17/89 SEAGRASS BIOMASS STA DEPTH DATE Epfr(x) Epfr(SE) Epfr(n) EP(x) EP 1g\SH 1g\SH 1g\SH(n) Epfr(x) Epfr(SE} Epfr(n)(shoots) EP 1g\SHCx) 1g\SHCSE) 19\SH(n) EpFr(x) EpFr 34.99 ..::. ' 12.70 7.06 I 40.90 <2-3m) 28 34.40 3. 4-4 37.58 29 7.30 <0.5m) 19.20 41.90 I 28.40 ( 1-3m) ~_)<) 15.70 (0.5-1m) "?. 65 19.99 I 27.70 (1.5-2m) 31 39.70 7.43 35.35 ~'") 14. 10 (0.5m) 4.37 16.53 ·-.._ 27.00 <1-1. 5m) 33 21. 00 C0.5m) 6.52 34.65 I 37.50 <1-3m > 34 12.50 (0.5-lm) 14.23 45.84 ,...,, Li .80 (1.5-2m) I AVERAGE LIGHT TRANSMISSION (% M-1) 1987 NUECES ESTUARY I All data collected using LI-190SA and LI-192SA sensors I NOTES: I 1. October: At most stations, turbidity decreased from surface to bottom. This trend was more pronounced in Corpus Christi Bay, and least pronounced in Nueces Bay. I I Station 2: Data too variable to ~eport 4A: River 7: Channel 15: Strong surface current 16: Dredging area, rough I 2. 20 Oct: Corpus Christi Bay I 21 Oct: Nueces Bay 8 Dec: Corpus Christi Bay 9 Dec: Nueces Bay I I I I I I I I I LIGHT TRANSMISSION-NUECES BAY 16 FEBRUARY 1988 I STA DEPTH SURFACE UNDERWATER % m-1 ( m) PFFR PFFR I ------------...-----------------------·---- ..• 1 0.5 1082.0 0.025 -21.35 0.00 I 2 0.5 1061.0 0.048 -19.99 0.00 3 0.5 793.5 2.230 -11. 75 0 .. 00 I ..J t:" 0.5 804.6 0.058 -19.07 0.00 1. 0 813.4 0.000 0.00 0.00 6 0.5 607.6 0.039 -19.30 0.00 7 0.5 671.4 0.812 -13. 4-4 0.00 8 0.5 556.5 0.368 -14.64 0.00 I 9 0.5 286.3 1.861 -10. 0.5 1999 1041.0 -1.30 27. 12 1 2011 782.8 -0.94 38.93 1. 5 1998 461.0 -0.98 37.62I 2 1990 243.5 -1.05 34.98 3 1980 87.6 -1.04 35.37 I 20 0.5 2028 1415.0 -0.72 48.68 1 2043 793. 1 -0.95 38.82 I 1. 5 2015 414.4 -1. 05 34.84 2 2013 248.5 -1. 05 35. 143 2023 66. 1 -1. 14 31. 96 21 o. :3 1 i=r-, 2055 1302.0 -...JL 21. 84 • 0.5 2053 1365.0 -0.82 44.21 ; ,...,,..., 1 2046 602. 1 -l.. ~::..::. 29.43 I 1. 5 2048 566.2 -0.86 42.44 2 2061 198.0 -1. 17 31.00 .-,,..., .,;:.L,. 0.3 2043 1674.0 -0.66 51.48 I 0.5 2046 1397.0 -0.76 46.62 1 2037 684.0 -1. 09 33.58 1 c. • -...J 2040 336. 1 -1. 20 30.05 23 0.3 1565 1160.0 -1. 00 36.85 I 0.5 1549 840.0 -1.22 29.41 r-,c:: 1 1577 451.4 -1 • L-...J 28.62 I 1. 5 1601 240.0 -1. 27 28.22 2 1571 135.5 -1.23 29.37 3 1576 40.5 -1. 22 29.51 24 0.3 1441 1126.0 -0.82 43.95 I 0.5 1138 508.4 -1.61 19.96 1 1440 164.8 -2. 17 11.44 1. 5 1464 84.7 -1.90 14.96 2 1456 33. ~3 15. 1'") I -1. 89 ..:.. 3 1454 6.4 -1. 81 16.37 4 1460 1. 3 -1.75 17.41 1 r-,c:; 25 0.3 1348 926.9 -• L...J 28.70 I 0.5 1350 620.0 -1.56 21. 09 1 14-20 297.2 -1. 56 20.93 1. 5 1355 138.2 -1. 52 21.83 I 2 1366 61. 1 -1. 55 21. 15 3 1398 11. 5 -1. 60 20.21 26 0.3 1146 948.7 -0.63 53. 2""? 0.5 1105 466. -, ( --1. 72 17.84 I LIGHT TRANSMISSION -CORPUS CHRISTI BAY 12 APRIL 1988 STA DEPTH SURFACE UNDERWATER k % m-1 (m) F'FFR PFFR I 1 1036 138. 1 -2.02 13.33 1. 5 1034 69.4 -1. 80 16.52 2 1044 28.4 -1. 80 16.49I 3 1076 5.6 -1. -15 1"('. 36 4 1093 1. 1 -1. 74 17.61 i= ...J 1 l.13 0.1 -1.81 16.32 I r"\-:0 r"\C: L( 0.5 1680 842.2 -1.38 L...J. 13 1 1729 481. 3 -1. 28 27.84 I 1. 5 1700 234.6 -1. 32 26.70 2 1714 124.2 -1.31 26.92 3 1711 29.6 -1. 35 25.86 28 0.5 1986 670.6 -2. 17 11. 40 I 1 1989 406.4 -1. 59 20.43 1 • ...J 1984 171.6 -1. 63 19.56 i= 2 1977 68.3 -1. 68 18.58 29 0.3 1799 1281.0 -1. 13 32.24 I 0.5 1804 1107.0 -0.98 37.65 1 1781 554.1 -1. 17 31. 11 I L5 1818 293.3 -1.22 29.64 2 1818 165. 7 -1. 20 30. 19 3 1814 51. 9 -1. 18 30.58 l.j. 1814· 15.4 -1. 19 :Jo. 37 30 0.3 1833 14·68. 0 -0.74 47.70 I 0.5 1846 1130.0 -0.98 37. 4.7 1 184-7 715.0 --0. 95 38.71 1 c:· I • ...J 1886 460.0 -0. 94. 39.04 2 1884 269.0 -0.97 37.79 31 (D) 0.3 1780 1340.0 -0.95 38.81 -1. 1,.._, 0.5 1762 1008.0 ..:.. ~52. 73 1 1800 555.4 --1. 18 ~30. 86 I 1. 5 1823 329.3 -1. 14· 31. 95 ...... L 1793 181.4 -1. 15 31.81 3 1792 29.6 --1. 37 25.46 I 32 0.2 1071 860.4 -1.09 33.46 0.4 1117 441.0 -2.32 9.79 I 0.5 9-19 338.2 -2.12 11. 94 1 981 129.6 -2.02 13.21 33 0.2 993 990.7 -0.01 99.10 0.4 933 664.3 -0.85 42.77 0.5 1134 403.4 -2.07 12.65I 1 1143 140.7 -2.09 12.31 I 1..5 l 106 80.5 -1. 75 17.44 2 1094 26.6 -1. 86 15.58 3 1115 4. 1 -1. 87 15.47 34 0.5 1554 1305.0 -0.35 70.52 1 1555 718.1 -0.77 46. 18 I 1. 5 1563 561.0 -0.68 50.51 2 1571 307.4 -0.82 44.23 I TRANSMISSION -NUECES 13 APRIL 1988 LIGHT DEPTH