• • • • • • • • • • MARINE ECOSYSTEMS A Book Prepared by the MNS 354R, 1981 Class of The University of Texas at Austin December 17, 1981 Compiled by Prof. Carl H. Oppenheimer THE LIBRARY OF THE UNIVERSITY OF TEXAS AT AUSTIN • MARINE ECOSYSTEMS A Book Prepared by the MNS 354R, 1981 Class of The University of Texas at Austin • December 17, 1981 • Forward • • The book is a compilation of the students efforts in the Fall 1981 course MNS 354R Marine Ecosystems. The course was organized as a student participation exercise. Each student selected or was assigned in pairs to one of the marine ecosystems in the table of contents. The students were required to develop, outline and present before the class, material for a 20 page paper. This included a literature search, preparation of slides and overhead projections, etc. Most students presented two class lectures on their topic. During the course, the Instructor reviewed progress, presented spe • cialized material on ecosystems in general and directed the students efforts. One field trip to a typical Texas Coastal Ecosystem was made early in the course. • The final product is the following material. It has not been corrected, but in some ecosystems a table of contents was added by the Instructor. The final reports were assembled and one copy was distributed to each ecosystem team . • Carl H. Oppenheimer • Course Instructor December 17, 1981 • • MARINE ECOSYSTEMS Table of Contents Title 1. The Rocky Shoreline 2. The Sandy Beach Ecosystem 3. Estuaries 4. The Calcareous Estuarine Ecosystem 5. The Benthic Continental Shelf Ecosystem 6. The Ecosystem of the Deep Ocean 7. Coral Reef Ecosystems 8. Rifts 9. Plankton of the Shelf 10. Plankton of the Open Ocean 11. Continental Shelf -Pelagic 12. Contrasting Chemical, Biological, Geological, and Physical Parameters of Polar Marine Ecosystems 13. The Gulf of Mexico as a Regional Ecosystem 14. Mediterranean and Black Seas 15. Marginal Seas Author(s) Paul Froehlich Greg Berkhouse Matt Mahoney Terri Osborne Linda Grace Ron Anderson Lisa Richards Elizabeth Andrews Mark P. Hemingway Mary E. Lyons Tracey Cather Kirt Shultz Jim Baldwin Kevin Kelly Nirmal Shah Jorge Alberto Gani Jeff Dillaha Ann M. Seman Jeff Heimann Jonathan Dunn Mark Kasmarek Jim Karabaic Jody Cadenhead Brenda Kirkland Michael Murray Kevin Zonana • • 3 23 • 37 70 • 89 114 • 143 175 • 194 212 • 240 265 • 289 306 • 326 • • • 1. The Rocky Shoreline Paul Froehlich OUTLINE • I. Introduction II. Geographic Distribution • III. Geology A. vuZcanism, tectonic B. beach materials IV. Physics A. particZe and beach shape • B . forces at work v. Flora and Fauna A. zonation (tid.al) 1. Zife of spZash zone 2. Zife of high tide zone• 3 • life of mid-tide zone 4. life of low tide zone VI. Conclusion • ~ • • • • • • Paul Froehlich, Marine Ecosystems, Fall 1981 The Rocky Shoreline • Over the c~eturies, man has discovered and colonized many new areas. Our own United States were discovered through exploration into unknown and uncharted areas by men spurred on by visions of riches, religious freedom or other tangible e reasons. In the middle part of the twentieth century, man turned to conquering the unknown expanses of space, due to a growing void of unexplored areas on earth. Space colonization no longer seems as far fetched as it once did, and exploration e for minerals will undoubtedly keep the space exploration interest surging. Also in the twentieth century was interest mounting in another frontier. As for the heavens above, man has slways been fascinated by their magnitude. Man has also ~ been fascinated for centuries, by the unknown of the worlds' oceans. Only in this century though, has man been able to probe some of what the oceans have to offer. As world and United States mineral supplies will dwindle in the years to e come, more interest seems warranted for the worlds' oceans. Man also needs to know more about the ocean and its life, for all life once came from the ocean, and if we should choke off our oceans with man's waste and pestilence, then we • will surely choke ourselves. As modern man moved fopl;)ard in the industrial age, increasing amounts of pollutants were dumped into rivers and the oceans. All wastes eventually ended • up in the ocean, as do all drainage systems. During the early seventies, pollution peaked and has since leveled off and declined slightly in the last few years. Man finally has realized how important the oceans are for his survival. Increased e awareness is what is needed to keep the worlds. 1 oceans clean enough for life to flourish in them. • • • (2) • Of particular importance and interest to the average human terrestrial being is the area where our environment meets the sea. The shore, or shore line is the area where the sea meets land. Shores are made of many materials, of various • chemical and mineral makeup and of variably sized and shaped particles. Processes on sandy shores are similar to, yet different from processes on rocky shores. Sandy shores are another story, not to be told by me. I, in this report, am basic• ally interested in the processes, froces and life of rochy shorelines. But one may ask, what is the difference between sandy shores and rocky shores, and how does one tell this difference?• As one might imagine, the difference is one of particle size. Sand particles are defined as particles smaller than two millimeters in diameter. Rock particles are those particles larger than two millimeters on up to boulder (larger than 200mm) • size. (Table 1) Many beaches have both sand and rock all year long, others seasonally, as dictated by tide and wave action. For this paper, I will limit my discussions to beaches known to be mostly rock, yet seasonal sand movement is important and will be discussed later. Geographic Distribution • Rocky shorelines are located worldwide and located at least marginally on all continents of earth. No continent has all sandy or all rocky shores, but a proportional mix, dependent upon local geology, wind, wave and tidal patterns. • On our own North American continent, we have rocky shores all along the West coast, and along the Northeastern coast. In South and Central America, rocky shores are abundant, and rugged rocky beaches are commonly the rule. Between • these rocky areas, lie sandy beaches that aren't of such high energy as the • (3) • rpcky areas. As in North America, the western coastline of South America seems to be slightly rockier than the eastern coast. The South Pacific islands • are usually rocky from vulcanism, with basalt being the predominate rock. Australia has many miles of rocky coastlines. Japan also has sections of coastline composed of mainly rock, with little sand. Asia has a few rocky beaches, • but many beaches here have sand and thick vegetation dominating many areas. Africa has a long varied coastline with many rocky sections, such as the Cape of Good Hope a.rea in South Africa. Much of the African-Atlantic coastline is • sand beaches moving up into immense coastal dunes. On the European continent, rocky shores are predominate in some areas, such as Norway, SWeden, Ireland and Great Britain. Many areas have rocky beaches due to the power of the North • Atlantic and North Sea. Portugal and Spain have rocky stretches interspersed with sand beaches, dependant of local tide and wave power. In the Atlantic, Iceland is mostly rocky rugged basaltic coastline still undergoing volcanic • activity. Iceland sits squarely on the Mid-Atlantic ridge, an area of newly foY'111ing sea bed. So one might say that rocky shores can be found here and there, just about everywhere. But what are some of the processes and materials • that go into the making of one of these transitional shore areas? No two areas developed in the exact same way, but certain trends and natural processes show some similarities and basic modes sometimes appear, allowing some homologous • observations between areas. Space will not allow me to report on every rocky beach in the world, so I will attempt to describe certain types of beaches and then report in more depth on the processes and inhabitants of these exem • pla.ry sections of rocky shoreline. • • • (4) Geology • • What differentiates many of these rocky beaches from other rocky beaches is the makeup of the rock itself. The majority of continental shores around the Pacific are andesitic or granitic, with the islands away from the contin ental margins being more purely basaltic. This is due to numerous factors. The andesitic areas around the Pacific are due to tectonic movement carrying basaltic sea floor, organic sediments and other sea floor minerals underneath the continental Zand masses where this andesite is found as this sea floor material moves downward below the continental land mass, intense heat and • pressure melt the basaltic sea floor and other matter incorporated with it into andesitic (or of sialic origin, granitic) magma. This tectonic movement, of stress buildup and sudden release, is the reason for areas of numerous earthquakes being located along plate boundaries. Japan has many earthquakes every year attributed to tectonic movement and the nearby location of a triple juncture of trenches. Also, this magma tends to flow out at sometimes in vulcanism around the area of submerging plate margins, usually several miles inland. One can even form a line marking areas of sea floor differences all the way around the Pacific. (Ill. 3) Basaltic crust is the norm on one side, • with more andesitic rock on the other. Andesitic rock is more acidic than basalt, being tainted by the granitic continental crust, which ''floats" on the heavier, denser basaltic sea floor crust. This tectonic movement and melt• ing of lithologic material is one of the most important factors in determining native rock type in many areas. As one can see, volcanoes resultant of tectonics ring the Pacific Zike a ''ring of fire". (Ill. 2) The Hawaiian islands, • • (5) • a very rocky shore habitat, are purely basalt. They were formed as sea f'Zoor movement carried each new island to the northwest after it was formed over a • stationary volcanic ''hot hole" in the Pacific floor. Therefore, the oldest of the Hawaiian islands, Kauai, is the farthest island out in a northwest direction, having been carried there since its formation thousands of years • ago by sea floor spreading. The Japanese islands, by comparison, are andesitic due to their Pacific margin location, away from the central region. Other rocky shores ·around the world came about in different ways other • than tectonic creation of molten building material. Many rocks that now form rocky areas were originally laid down as sedimentary rocks. Rocks such as limestone, sandstone and dolomite were deposited millions of years ago by • accretion in mostly shallow seas. Later, after these rocks were removed from under water by reduction in sea level or uplift of the area, they were shaped and molded by area elements. Many times, these sedimentary rocks end up as • coastline material, forming rocky beaches with interesting structures. Sed imentary rocks are much less resistant than igneous rocks, so sedimentary coastlines form cliffs and structures such as arches and stacks. Igneous • shores also form cliffs, but do not form them as rapidly as sedimentary rocks will. The time required to ''mold" a sedimentary coastline in much less than that of an igneous coastline. Grottos, or caves underneath a cliff that are • over sea level, form in limestone areas occasionally, as on the Isle of Capri. The motion of the water, combined with the solution work of saltwater, and water tossed debris scour out rock behind the cliff face, forming grottos. A stack is • basically a cut off arch separated from shore, forming a tower. Shorelines • • • (6) composed of sedimentary rocks are fairly common, examples being the Cliffs of • Dover in Great Britain, and the shales and rrrudstones of California. There are also beaches composed of metamorphic rock, but these are not large in nwnber, most beaches having fe~ metamorphic rocks. Basically, we will be concerned • with beaches of igneous (molten) or sedimentary (deposited) origin. Physics • The physics of any shoreline are very important in that the shape of the beach itself is resultant of the physics of the elements involved. We can tell many things just by the particles that make up a beach. Their shape will tell • us if the beach is a high energy beach, or a low energy beach. Well rounded, smooth stones usually indicate a high energy beach, for it takes motion to smooth off rocks. A high energy beach also has larger particles due to larger • waves increased load moving power. A beach of fairly large, well rounded rock could be described as a high energy beach. Low energy beaches, such as those on the Gulf Coast, produce smaller particles, usually sand, due to their inability • to move larger particles. The sand grains may well be rounded also, for some sand beaches can also be of relatively high energy. However, as we are covering rocky beaches, we will limit ourselves to such areas. Basically though, the • larger the rock fragments thrown up on the beach, the higher energy the beach produces. At Waimea Bay, on the north shore of Oahu, for example, huge winter swells rolling down from storms in the Aleutians cause thirty to forty foot • waves every four to five years. Surfers held under by these mountainous waves have reported seeing huge boulders, the size of automobiles bouncing and rolling • • (7) /() • • • • • • • • • • • along the bottom. The power to move such boulders must be quite strong and serves to show some of the raw energy possible. Wave tossed rocks and debris can be a very corrosive agent upon shore rock. This is called corrasion. Not only do the forces of a shoreline shape separate particles, they also shape the shoreline itself. Many rocky beaches in California are coated with a veneer of sand in the relatively calm, small wave conditions of summer. However, when larger swells start rolling down from Northern Pacific winter storms, these beaches are stripped of sand down to the rock layers. This yearly migration of sand has been studied in California in conjunction with increasing dam utilization on California's rivers. As the state dams up more rivers, the sediment car~ and terrigenous material eroded away will not reach the coast and can't be ried by longshore currents to beaches that for years have been sandy in summer. Tourism could be hurt, for many people don't Zike to go to beaches with no sand and all rock. It makes for a tough game of football or frisbee on the beach. Man-made groins and jetties also slow down in some cases this yearly flow of sand. In other areas, man-made structures also cause sand buildup. The beach is also a result of wave refraction along co~sts. (Ill. 4) This wave refraction, along with coastline make up, shapes the coast into head land and coves, headlands being usually more resistant rock. Another important factor in beach shaping is the daily fluctuation in tide levels on the beach front. The width of a beach in directly proportional to the range of the tides in the area, and inversely proportional to the slope of the shore (Cotter pg. 73). Areas with tides that fluctuate a great deal usually have a wider shore area than areas that have a small tidal fluctuation. Tides are very important in the beach zonation of organisms as will be discussed later in the faunaZ section. • • • • I I • • • • • • (BJ Beaches that have a steeper shore front are usually of coarser materials than gently sloping beaches. A steep shoreline also lends itself to more powerful waves. The deeper the water is close to the shore, the further in waves will come before they begin to feel bottom. Waves on the Gulf of Mexico's beaches in Texas are greatly slowed by the shallow, very gently sloping bottom of the expan- These waves slowly spill over, and are called sive continental shelf in the area. (oddly enough) spilling breakers. These low energy waves are typical of our Gulf Coast. Steep beaches in Hawaii and California, however, breed a much more powerful ''plunging" breaker by swells coming into very quickly shallowing water out of deep water. The mass of this wa.ter hits shallow water, raises up and falls forward powerfully, the base of the wave hitting bottom quickly and slowing quickly. The troichoidal wa.ve theory explains this by showing the circular pattern of a particle in a sea wave action. The bottom s'lows and the top pitches forward quickly. Another physical aspect of some shorelines such as that of the Acadia shoreline area of New England is the effects of glaciation on rock. Many areas once glaciated rebound once the tremendous weight of glaciers is removed. These areas form platforms of shore rock on some shores such as Iceland. In New England, there are channeled striations ritnning NW by SE toward the sea, sea with impressions filled by seawater, and "fingers" of rock above level, forming islands. This granite is scarred heavily by glaciers and the very shoreline configuration itself is due to glaciation creating the channels and islands. This coastline was "combed" out by glaciers. The movement of water on a coast is the main shaper of shorelines, by far . (9) • ~!here allowed to attack land unslowed, the cliffline retreats, forming a wavecut terrace. These features are common West coast rocky shores. Coastlines • generally develop in a pattern described in stages by geologists. The relative development of a shoreline can be described as young, mature, old, etc. These • terms have certain requirements that detail what each beach will exhibit, as features, in each stage. Basically, just the relentlessness of the sea is the major factor of wear on rock coastlines. The movement of seawater and its elements continually break down the rock. Longshore currents move material • laterally down the coast, depositing it where the currents slow. Rocky material of any size is rarely moved by longshore currents, unless the currents • are abnormally strong. This longshore drift is more pronounced in sandy areas. Rocky shores go through change continually, but change is sometimes hard to see if not accentuated by a major storm event or geologic unstableness. • Observation over many years is the only sure way of correctly identifying changes in the morphology of a rocky beach. This observation is not always possible, and we must rely on observations made at a point in time. Much • can be said for the life on a rocky beach that lives on and amongst the rocks. As time has past, sea levels have changed. What is now a rocky beach could have once been a land locked volcano. We have paleontological evidence of • many acient rocky shore areas, and study of the life of these ancient shores can help us learn more about coastline life, its' evolution and its' relation to life toc:lirrs. ln.r:uaud bo11orr. dreg of f/. r '"a'~' ac afwor in fron: o! thr hudiDndz lx n6 th• luv o! CTI uiemnin;, •.-a•'< , w.-raf'F' "'/; i.!,' (.,; nb rr: b•rol crs 1 • f'r ·~ ; \ ·, \ i ·1 \ '. i \ \r' 1 \ ' • • • • • • • • • • '' / .... • • .J.3 Greg Berkhouse Matt Mahoney • 2. THE SANDY BEACH ECOSYSTEM Table of Contents • 1. INTRODUCTION TO THE ECOSYSTEM Definitions and Limits. . . . . Zonations. . . . . . . . . . 2. FORCES ON THE BEACH General . . . . . . . . . . Waves and Slope . • 3. SAND Sources. . . . . . . Properties 4. CHARACTERISTICS OF BEACH WATERS Sea Water . . . . . . . . . . • Interstitial Water . . . . . . . . . . 5. CLIMATE General. . . . . . . . . . . . . . . • 6. PRIMARY PRODUCTIVITY Parameters . . Annual Cycle . . . . . . . . . 7. NUTRIENTS Sources. Nitrogen . . . . . . . Phosphorous. . . . . . . . . . • Other Nutrients . . . . . 8. MICROORGANISMS Bacteria . . . . . . . Fungi. • Algae . . 9. MEIOFAUNA Description. Types. . 10 . MACROFAUNA • General. . . . . . . Types. . . . . . . . . . • 11. MAN'S INFLUENCE ON THE BEACH Man on the Beach . 12. FLOW DIAGRAM . . . 13. BIBLIOGRAPHY . . • 1 1 2 2 2 3 3 3 4 4 4 5 5 6 6 6 7 7 8 8 9 9 11 12 13 • • • • • • • • SUPRATIOAL INTERTIDAL SU&TIDAL. O~-$HORE. OflP-SMO~~ L""IT LU11T Zonations. The sandy beach is divided into three zones according to tidal ranges, which determine time of exposure and distribution of energy, which in turn greatly influence faunal and floral distribution and zonation. The three zones are: the subtidal, which extends off-shore from the low tide level and is never exposed; the supratidal, which extends on-shore from the high tide level and is always • Greg Berkhouse Matt Mahoney THE SANDY BEACH ECOSYSTEM INTRODUCTION TO THE ECOSYSTEM Definitions and Limits. In order to discuss the sandy beach as an ecosystem, it is necessary first to define the terms sand and beach, and to set the limits of the ecosystem. Sand is a description of size, not composition as might be expected, and applies to unconsolidated rock detritus falling between 2mm and .0625mm, according to the commonly accepted Wentworth size scale (Folk, 1974). A beach can be defined as an accumulation of rock fragments subject to movement by ordinary wave action on-and-off shore, and along shore in accordance with currents (Bascom, 1964). We will set the on-shore limit of the beach just before the dune so as to disclude any terrestrial vegetation, and because the marine influence at this point is minimal. The off-shore limit is set where the wave base (one half of the length of an average wave) intersects the bottom at low tide level. This will assure movement of the sand, and will exclude shelf fauna and flora which inhabit lower energy systems. SANDY BEACH • exposed; and the intertidal, which lies between the tidal levels and is alternatingly exposed and submerged. The lateral extent of these zones, and so the lateral extent of the beach, is largely determined by the slope of the beach. • FORCES ON THE BEACH General. Once the terrestrial material is brought to the coast, it is acted upon by many different forces, such as waves, longshore currents, tides, wind, and • the fluvial system from which the material is derived. The geographic shape of the beach is determined by the interaction of these forces, as the sand is re • worked and transported along the coast . • Waves and Slope. Waves are the most influencial of the physical forces acting on the beach, supplying energy that not only shapes the beach but affects the eco system as well (Bascom, 1964). On beaches having a steep slope, wave energy is high and abrasion of sand grains is great. In areas of much abrasion (ie. where the waves beat on the shore), micro-and meiofaunal abundances are minimal. High • energy beaches tend to have well sorted sands of small grain size, and thus a low oxygen content in the interstitial water (Brafield, 1978). Conversely, beaches having a gentle slope have low wave energies and therefore very little abrasion. • Low energy beaches are characterized by poorly sorted, coarser sands which allow a higher oxygen content. Waves due to storms have generally higher energy levels I • than normal waves on either type of beach, and can be detremental to beach fauna. Dislodgement by waves can result in organisms being transported up or down the shore to areas unsuitable for their existence. Storm waves can also dump large amounts of sand and organic debris on the beach and smother organisms in their own • habitat (Tait, 1972) . SAND Sources. Beach-forming sand can be derived from terrestrial or marine sources. • The main constituent of land-derived sand is the mineral quartz, due to its dura bility and its abundance ·in erodeable terrain. Feldspar, various micas, olivine and pyroxenes (basaltic minerals) are also present as well as the heavy minerals • zircon, rutile, and tourmaline (Folk, 1974). 3 Sand derived from marine sources is composed of carbonate minerals, and is • mostly detritus of shell fragments~calcite or aragonite. Oolites, sand-sized particles of calcite precipitated around a nucleus, may sometimes form entire beaches. On low energy beaches, glauconite derived from fecal pellets is also • present in varying amounts (Folk, 1974). Properties. The two properties of the sand which most influence the sandy beach ecosystem are sorting and size. The sorting of the sand greatly determines • the amount of interstitial (pore) space which in turn largely determines the abundance of the meiofauna which live among the sand grains. Oxygen content of the interstitial water is a function of grain size, and also affects meiofaunal • abundance. These two parameters will be more fully discussed later in this paper. CHARACTERISTICS OF BEACH WATERS Sea Water. The composition of the inundating sea water in sandy beaches is • much the same as in the rest of the seas, disregarding for the moment the nutrients. The principal cations are Na, Mg, Ca, K, and Sr, and the principal anions are chloride, sulfate, bromide, and bicarbonate (Tait, 1972). The salinity of the • sea water also falls within the range of normal ocean water of 32-35 g/kg (Tait, 1972). • Interstitial Water. The interstitial water of the beach has unique characteristics. The salinity of this water fluctuates with the tide. When the beach is submerged by the tide, the interstitial salinity is generally the same as that • of the sea water, but when the tide is out, and fresh water (rain or terrestrial drainage) is running over the sands, the salinity greatly decreases (Brafield, 1978). Organisms living in the sands must be able to withstand these daily fluctuations. • Oxygen content of the interstitial water also differs from that of the sea water. Generally, the dissolved oxygen content decreases with depth. In very fine grain beaches, only about the uppermost 2cm of sand contain high enough levels • to support life, although in coarse grain beaches life exists as deep as lm below the surface (Brafield, 1978). In these coarse grain beaches, however, exposure due to low t i de temporarily decreases the oxygen content of the sand, another daily ~7 4 ~ cycle which meiofaunal organisms must be able to withstand (Brafield, 1978). There are also seasonal affects and the oxygen content is at its lowest during the summer when higher temperatures cause an increase in the abundance of microorga e nisms (Brafield, 1978). • CLIMATE General. The climate of a sandy beach, as might be expected, is determined • by its latitude and its availability to warm or cold oceanic currents: beaches near the equator will have higher average temperatures than those of high latitudes, and will have warmer waters due to equatorial currents (Tait, 1972). Climate, • however, has little influence relative to seasonal variations in temperature, which greatly affect productivity. PRODUCTIVITY • Parameters. The factor most influencing the primary· productivity of the sandy beach ecosystem is temperature. As temperature increases in the annual cycle, the phytoplankton increase their photosynthetic activity, and production rises. Growth and metabolism are also stimulated by increasing temperatures (Tait, 1972). Waves affect productivity on the beach. Sediments are stirred up by wave ~ action, releasing nutrients into the water column. Conversely, the stirring up of sediments also decreases illumination as light cannot penetrate the water (Tait, 1972). Waves, as temperature, follow annual cyclic variations. • The Annual Cycle. In the winter, wave energy is at its maximum, and the water, though relatively high in nutrient concentration, is poorly illuminated and the quantity and growth of plankton are minimal (Tai.t, 1972). • In the spring, rising temperatures stimulate planktonic growth and activity• Wave energy is decreased and productivity soars in the well illuminated water. The concentration of nutrients is initially high (due to nonproductive winter e months) but soon decreases as a result of rapidiy growing phytoplankton, such as the diatoms which reach their maximum abundance in the spring. The growth of phytoplankton triggers a gradual increase in beach zooplankton (Tait, 1972) . • In the sunnner, wave energy is very low but the nutrient supply is depleted from the high spring production. There is little repletion because the waves are • building up the beach rather than eroding it. The phytoplankton population is dec·~·eased by the grazing of zooplankton, which reach their peak in the summer •(Tait, 1972). In the autumn, illumination decreases as the wave energy begins rising, but the system is once again replenished with nutrients, not only by the stirring up • of sediments, but also by input from fluvial systems which have high nutrient concentrations at that time of the year (Pugh, 1976). This produces a slight increase in both phytoplankton and zooplankton, which soon fall to their minimum as the I lower temperatures of winter set in (Tait, 1972). NUTRIENTS Sources. The sandy beach ecosystem receives its greatest input of nutrients • from terrestrial drainoff, mainly rivers and streams. Because of the large amounts of nitrogen and ph~sphorous in these terrestrial waters the beaches have high concentrations of nutrients relative to those of other marine systems (Tait, 1972). • Large amounts of nutrients are also present in organic debris which accumulates on the beach from both the land and the sea. From these materials, saprophytic bacteria and fungi draw their nutrients (Rheinheimer, 1971). · Nitrogen. Nitrogen is present as nitrate (N0), nitrite (N02), ammonium (NH), 34and as dissolved organic nitrogen; it is present most abundantly as nitrate, and the cycles of the lesser nitrogenous nutrients roughly parallel the cycle of nitrate I (see graph). 30 20 • 10 10 10 Mar Apr May Jun Jul Aug Sep 1974 :<9 6 • The depletion of nitrate during spring and early summer is due to phytoplankton growth and activity, and the autumn repletion is due to the activity of nitrifying microorganisms, enhanced by terrestrial drainage and f1uvial discharge, which are • substantial during that season (Pugh, 1976). The concentration of nitrate in the interstitial water is roughly twice that of the inundating sea water, possibly because the nitrifying organisms need surfaces on which to carry on this activity • (Pugh, 1976). Phosphorous. Phosphorous is present as both inorganic and organic phosphate (P0). Phosphorous cycles roughly parallel those of nitrate for both sea and inter 4 • . · 1 h h h 11 1 (Pugh, 1976). Other Nutrients. · Silicon is present in sandy beaches mostly as silicate ions . • st1t1a water, t oug on a muc sma er sea e; phosphate rare1y exceeds · 2rug-at./liter • It is relatively low in concentration, falling to its minimum in the spring when the diatom population is at its peak (Tait, 1972). Iron and manganese, two impertant plant nutrients, occur in beaches in high concentrations relative to normal • oceanic water due to their input by terrestrial drainage. Without them, photosynthesis cannot occur. MICROORGANISMS . Bacteria. The bacteria in the sandy beach are much more abundant (some 2-3 orders higher in concentration) in the sand than in the inundating sea water • Bocletiol conlenr ot sand • • 6 7 • (Rheinheimer, 1971) 7 3o (Andrews, Floodgate, and Pugh, 1976), aud the overall bacterial count fluctuates • very little on an annual basis. Due to the abrasion of the beach slope by tides and waves, most bacteria occur above the high tide level in the supratidal zone, as the figure demonstrates. The bulk of beach bacteria are saprophytic, feeding • on organic debris, and belong to the orders Pseudomonadales and Eubacteridles, though Hyphomicrobia, Chalamydobacteria, Cytophagas, and Spirochaetes are also represented (Rheinheimer, 1971). Nitrifying bacteria such as Nitrososystis oceanus, • which oxidize ammonia to nitrite or nitrite to nitrate, occur in beaches and account for some repletion of the nitrate concentration (Rheinheimer, 1971). Fungi. Various fungi are present on the beach in both parasitic and sapro • phytic forms. Parasites, such as Leptolegnia marina, occur in muscles and crabs, or on algae, as do members of the genus Thraustochytrium. The saprophytic fungi include representatives of the genera Olpidium, Rozella, and Ectrogella (Rheinheimer, • 1971). Yeasts are present on the beach only in small numbers, as they prefer mud to sand (Rheinheimer, 1971). Algae. The physical nature of the beach largely determines the types of • algae present: attatched forms dominate in course sand, while motile forms dominate in fine sand, though both forms are present in each type of sand (Round, 1963). Algae on the sandy beacharevery distinctly zoned according to tidal ranges. • In the subtidal zone, diatoms such as Amphora coffeaeformis, ~· laevis, ~and ~ macilenta are found, as well as the cyanophytes Holopedia and Anabaen~ (Round, 1963). In the intertidal zone, attatched diatoms occur from the genera Synedra, Rhabdonema, • and Gammatophora, while Amphora, Caloneis, Diploneis, and Navicula supply the motile algae (Round, 1963). Also present in the intertidal zone is Phaeocystis, which enters the sand profile from the inundating sea water. The bloom of this phyto • plankton is largely responsible for nitrate depletion of the ecosystem in the spring and early sunnner (Pugh, 1976). Algae are rare in the supratidal zone as the beach • is normally too dessicated to support algal life. The algae of ·the sandy beach ecosystem are all photosynthetic and rely on the iron and manganese nutrients to carry out their photosynthesis (Round, 1963). • ·8 • 3/ Beach algae, like the bacteria, occur only sparsely in the areas of high energy where the waves beat against the shore. • MEIOFAUNA • Description. The meiofauna can be defined as .those organisms which pass thorough a O.Smm seive but are stopped by a O.OSrmn seive (Brafield, 1978). They inhabit the interstitial spaces between sand grains, and their size ar-d shape • (usually filiform~long and thin) are largely determined by this habitat (Kinne, 1972). Meiofauna are most plentiful in sands of medium grain size (0.25rmn-0.5mm) be • cause in finer sands the oxygen content is too low and in coarser sands the water drains away too quickly, making ciliatory movement impossible (Brafield, 1978). The greatest limiting factor, however, is the degree of sorting of the sand. • In lower energy beaches, where the sand is poorly sorted and smaller grains occupy the pores between.the larger grains, the meiofauna have little room and are therefore less abundant (Brafield, 1978) . Types. The most abundant of the meiofauna are the nematode worms, present in the sand up to hundreds of thousands per square meter. (Brafield, 1978) and pre• dominantly carnivorous. Copepods, minute crustaceans, are also numerous, most of • Coelogynoporo b1ormoto (turbellari;in) 2 mm • I' • .:;. .i., -i ,.. • .:seudos:omei/o roscov1ta 1gastrouich 1 0.25 mm Cy li ndropsyllis loevis (harpactJ cord copepod I 1 mm • 3.::;,:1 pes ~.·~us Nerillidium troglochaetoides 1:Jr:::: .rr:iae1 .'.) ~ ·~~ (archiannelid) 0.5 mm 9 which are nocturnal detritus feeders. Temora, Eurytemora, and Labidocera typify • beach-living copepods, and serve as a major food supply for fish which come up from the shelf when the tide is high (Crowder, 1931). Turbellarians, ciliated flatworms, are carnivorous and feed on small invertebrates. Examples of turbellarians are • Coelogynopera and Plagiostomum (Crowder, 1931). Meiofaunal archiannelids, such as Dinophilus, are present and are detritus feeders. Batillipes, a segrn~nted herbivore, is representative of beach-living tardigrades, and Pseudostomella is typical of • the meiofaunal gastrotrichs. The latter is a ciliated detritus-feeding organism (Crowder, 1931). MACROFAUNA • General. Due to the physical nature of the ecosystem, the ability to burrow is essential to macrofauna on the beach: waves have the energy to dislodge, crush, and abrade organisms living on the surface of the sandy bottom (Southward, 1965). • Burrowing is also a defense mechanism, as well as a means of avoiding salinity and temperature extremes of the sea water. • Diverse feeding mechanisms occur in beach macrofauna. Carnivores are present (though a minority), and suspension feeders, which pass large quantities of water through gills or branchial crowns and filter out the plankton (Brafield, 1978). • Detritus feeders inhabit the beach which swallow sand, either by inhalent siphons or by direct ingestion, and extract organic debris. By their activities, detritus feeders increase the amount of suspended particles which can clog the filters • of suspension feeders; the two are thus somewhat segregated: deposit feeders dominate fine sands because of their high concentrations of organic material, which leaves suspension feeders to dominate coarser sands (Brafield, 1978). • Types. Various crustaceans inhabit the beach. Amphipods, small nocturnal scavengers, such as Talitrus and Orchestia are found in the supratidal zone feeding on organic debris, while Bathyporia pilosa and ~· elegans occur in the intertidal and subtidal zones, respectively (Brafield, 1978). The burrowing isopod Alloniscus perconvexus inhabits the supratidal zone as it is an air breather. Crangon vulgaris, • l.U • To/11rus soltotor (1 .5 cm) 33 Coroplli11m •ol11ta1or (1 cm) Cronron •11l1om (5 cm) a shrimp common on sandy beaches, is nocturnal and highly carnivorous, feeding on ~ molluscs, worms, and other crustaceans. This shrimp is very durable; it can survive in temperatures from o0-3o0c and can withstand very low salinities (Yonge, 1963). Crabs, such as Carcinus meanas and Corystas cassivelanus are also carnivorous, and • move with the tide (Brafield, 1978). Phylum Mollusca is well represented on the sandy beach, as the infaunal shelled bivalves are perfectly adapted for life within the soft substrate. Cardium edule, • the cockle, is a suspension feeder which lives in the intertidal zone and can feed only at high tide. Other suspension feeders are Mya and Ensis (Brafield, 1978). Deposit feeding bivalves include Macoma baethica, Donax vittatus, and Tellina • tenuis, though Macoma can suspension feed when covered by tides. Gastropods are also present in the ecosystem. Some, like Natica alderi, are highly carnivorous, boring through bivalve shells and eating the organism at home. Hydrobia ulvae, a• herbivore, floats during high tide, but sinks, crawls, and burrows during low tide (Southward, 1965). Burrowing polychaete worms secrete a lining of mucus in their burrow which • hardens to a permanent structure called a worm tube (Brafield, 1978). Some are • &othyportio sp. (0.5-1 cm) • '" ., ' ''\·~" • ~;;;.:.~::.:.:·::. :·::...:::::. ~ ') ' ;-- ·ff .. -·--..:c ~ ~J) '. ~; ~1 ·· Neonthes ( = Nt rt rs) vlrtns (20 cm) Tvbu of Sot>ello ~nd Lo n1ct i',r~r-•co!a 1n • 1t.s bvrrow ._,, -·(cla mor1r~ •S cm) 31 11 deposit feeders, such as Ariencola marina, the lug worm, which inhabits the inter • tidal zone. Other polychaetes are suspension feeders which make use of a branchial crown, as are Lancia conchilega and Sabella pavonina; both occur in the subtidal zone. Still others are carnivorous, feeding on crustaceans and other worms. Ex • amples include Neanthes virens, Nephtys hombergii, and Glycera convoluta. Various echinoderms inhabit the sandy beach. The heart urchin Echinocardium cordatum, a deposit feeder, uses its spines to burrow, then lines the cavity with • mucus (Yonge, 1963). The delicate sea cucumber Leptosynapta inhaerens also lives on the beach. Astropecten irregularis, a carnivorous starfish, inhabits the beach, preying on molluscs, crustaceans, and worms. The starfish swallows its prey whole, later disgorging the shell or skeleton (Yonge, 1963). Several shelf organisms enter the beach at night during high tide, preying on • beach fauna and bringing to an end the ecosystem's food web. Juvenile flatfish, shrimps, and crabs constitute the bulk of the migrating shelf creatures. The sand eel Ammodytes, which burrows in the subtidal area during the .day, also prowls the • high tide waters at night (Barnes, 1977). MAN'S INFLUENCE ON THE SANDY BEACH Man and the Beach. Man's actions on the sandy beach have been only slightly • influencial to the ecosystem. Colonization of and building on beach areas may cause or deter erosion, but erosion is a natural process and occurs anyway. Of course, beaches subject to recreational use have lower faunal populations than isolated beaches. Organic compounds used by man, such as detergents and pesticides (not to mention oil), sometimes find their way to the beach where they can be quite detremental (Tait, 1972), but only on a local scale: overall, pollution on • the sandy beach is minimal. Man does assume the role of top carnivore on the beach, but as the beach lacks popularly-demanded fish in abundance, man's food supply from the beach is largely restricted to clams and other molluscs. For the most part, • man fits into the sandy beach ecosystem just as the other organisms. • SANDY BEACH BEACH ENERGY FAUNA SLOPE LOCAi i ON EROSION T'(PES ( §.E·) (TYPE OF) FLUVIAL S'{STEM ABUNDANCE O~ SAND WAVE IMPACT ZONE TEMPERATURE ANNUAL CYCLES NUTRIENT INPUT ~ 13 3(o • BIBLIOGRAPHY Andrews, A.R.; Floodgate, G.D.; Pugh, K.B., "An Annual Cycle, at Constant Tempera ture, in a Model Sandy Beach II. Microbial Biology, " Journal of Experimental eMarine Biology and Ecology, Vol. 24, 1976, North Holland Publishing Co., Amsterdam, Netherlands. Barnes, R.S.K. (ed.), The Coastline, John Wiley and Sons, (1977). Bascom, W., Waves and Beaches, Doubleday and Company Inc., Garden City, New York,(1964). • Brafield, A.E., Life in Sandy -Shores, Edward Arnold Ltd., London, (1978). Crowder, W., Between the Tides, Dodd, Mead, and Co., New York, (1931). Folk, R.L., Petrology of Sedimentary Rocks, Hemphill Publishing Co., Austin, (1974). • Kinne, O. (ed.), Marine Ecology, Vol. 1, Part III, Wiley-Interscience, New York,(1972). Pugh, K.B., "An Annual Cycle, at Constant Temperature, in a Model Sandy Beach I.Nutrient Chemistry," Journal of Experimental Marine Biology and Ecology, Vol. • 22, 1976, North Holland Publishing Co., Amsterdam, Netherlands. Rheinheimer, G., Aquatic Microbiology, John Wiley and Sons, New York, (1971). Round, F.E., The Biology of the Algae, St. Martin's Press, New York, (1963). • Southward, A.J., Life on the Sea Shore, Harvard University Press, Cambridge,Mass. , (1965). Tait, R.V., Elements of Marine Ecology, Springer-Verlag New York Inc., New York,(1972). • Yonge, C.M., The Sea Shore, W. Collins Sons and Co., London, (1949). • • • • • • • 1• • • • • • • • I. II. III. IV. V. VI. VII. 37 3. Estuaries Terri Osborne &Linda Grace Table of Contents Introduction: Definition and Origin Classification A. Mode of Formation B. Circulation 1. Salinity and Sedimentation 2. Influence on Organisms Temperature Chemistry Flora and Fauna of Estuaries A. Microflora B. Macrofauna C. Microfauna D. Mammals Man's Impact Bibliography -----·-· L 1~1do_ \',_i· 1 • C.-' ... 1 h_:t Yit3. Estuar i es 3g Terri Osborne &Linda Grace Introducti'on: Definition And Origin An estuary can be defined as a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water:··is measurably diluted with fresh water derived from land drainage, (Pritchal/ p.1). It is a basin in which ri~er water mixes with sea water. Such coastal bodies of water partly separated from the sea by barrier beaches or bars of marine origin are termed lagoons. As a rule, lagoons are elongate and lie parallel to the shoreline. Generally, lagoons are more shallow and more saline than typical estuaries, (Reid, p.97). The basic physiography of coastlines and shores is due to submergence, when the coastline migrates inland, and emergence, when the coastline is moved seaward. Both submergence and emergence may form estuaries, some times both processes actirgat different times.in the past. Features which develop¢' as a result of movements of sea and landJn relation to each other called initial form, and are due to tectonic factors, glaciation, and climate. Shoreline patterns resulting from the action of marine forces on the initial forms are termed sequential forms and are due to currents, wave action, tides, wind and so on, (Reid, p.94). In geologic history, estuaries are transient; changing in state, condition, or location. Today's estuaries are very young geologically, having been formed by the most recent rise in sea level .as a consequent of the retreat of the last glaciation. Their present forms are only about 8,000 years old. Once formed, estuaries are rapidly destroyed, becoming filled with sediments. Factors important in determining the rate of infilling of an estuary are stability of sea level (rises rejuvenate estuaries), rate of sediment influx, circulation within an estuary, and climate Cwhich affects weathering rates), (Schubel, pIII.7). Environmental conditions within an estuary or lagoon are very variable, • • • • • • • • • • and these conditions are constantly changing from time to time and from place • to place. Not only are they ~ones of transition between two very different environments, sea and fresh water, but also, due to tides and to fl,uctuations in the downflow of fresh wa~er, conditions at a particular point in the estuary may oscillate widely and very frequently. The organisms living i~ estuaries • must adapt to these rapidly fluctuating conditions. The different factors and process which operate in an estuary lead to many different ways in which • to classify them, (Barnes, p.51) . Claspi;f'1,cat1ont Mode 9f Formation • vne way in which to classify an estuary is on the basis of mode of formation, ..From th;is ·geomorphological standpoint there are four primary subdivisions; drowned river valleys, fjord-type estuarj_es, bar built estuaries, and estuaries produced by tectonic processes. Drowned tiver valleys are also called watersway coastal plain estuaries because thay are commonly found along a coastline with a relatively wide • coastal plain. These estuaries fill basins which were formed by subaerial erosion by rivers and which have retained their dominant ancestral traits. They • . are examples of primary coastlines shaped by fluvial erosion. These estuaries are generally relatively shallow with gently sloping bottoms. The cross sec~ tion is usually V-shaped, and the depth usually increases fairly µr::.i:r:'ormly • toward th mouth, (seaward). Drowned river valleys are found around the world and some well known examples include the Chesapeake Bay, Delaware Bay, Thames (England), Ems (Germany), Seine (France), Si-Kiang (Hong Kong), and Murray • (Australia). As in the case of Chesapeake Bay, the rise in sea level follow ing a glaciation flooded the valleys of several rivers. Not all the length of the drowned river valley would be classified as an estuary. There must both • be measurable amounts of salt and fresh water, "there will usually occur a short transition region in which the chlorinity will continue to drop about , 01% • and the ratios of the major dissolved constituents will undergo a rapid change. This point is the upper limit of the estuary. Upriver from this point the • cW..orinity and conductivity will remain relatively constant.", (Lauff, p.4). A Fjord is an estllary which fills a glacial trough. They are characteristicly narrow, steep-sided troughs, U-shaped in cross-section, and relatively • straight and long. They freq_uently have shallow sills at their~, mouth, which e:;;.;~'e -,·or:: ~:: or drowned morainic bars. Fjords are the deepest of all estuaries, some exceeding 800 meters, but their sills are much shallower. In some Norwegian fjords the • sills are so shallow that the fjord has estuarine characters only in the upper part of the water column, above the sill depth. The deepest waters are trapped and remain stagnant for long periods. In other fjords with greater • sill depths, such as in British Columbia, there is a slow but continual ex change of the basin water with the open sea water, (Lauff, p.6). Fjords are found in formerly glaciated areas in both the Northern and Southern Hemispheres, • (Schubel, p.II-6). Bar built estuaries are formed when offshore barrier sand islands and sand splits build above sea level and extend between the head lands in a • chain, broken by one or more inlets. The area enclosed by the barrier beaches is usually elongated parfallel to the coastline, with usually more than one river entering the estuary. It could be considered a composite system, part • being an embayment partially enclosed by barrier beaches, and part being a drowned river valley. Since the inlets connectim the estuary and the sea are small, tidal action is reduced. They are usually shallow, and wind is an imp • ortant mixing mechanism. Examples are Albermarle Sound and Pamlico Sound in North Carolina, and other good examples are found along the Gulf Coast, !'_Lauff, ·p.6). • Estuaries produced by tectonic processes is a classification for estuaries not clearly included in the other three devisions. They are estuaries which fill basins formed by faulting, folding, or other diastrophic movements, with • an excess sup-ply of fresh water inflow. An example is the San Fransisco Bay, (Lauff, p.6). • • 41 Classification; Circulation-Salinity and Sedimentation The classification of estuaries on their basis of mode of formation is of limited use. The classification based on circulation patterns is of much • greater value in understanding tm actions and effects of estuarine processes. The three causes of the water motion in estuaries are the wind, the tide, a.nd the river. Ah estuary,_ ca~ be dominated by one of these causes. These estuary • types based on cir~ulation patterns are the salt wedge, the partially mixed, the vertically homogeneous, and the sectionally homogeneous .estuaries. In a salt wedge estuary, the river discharge is hi~h compared with the .... • tidal flow, the fresh water flows outwards on the suface overriding a wedge of saline water. The surface layer becomes progressively more saline in a seaward direction while the lower layer retains its original salinity, the • salinity of the adjacent sea. There must be a slow movement of sea water up the estuary in the lower layer to replace the salt lost to the upper layer. It is river dominated, an1the estuary of the Mississippi River may be taken as • this, (Schubel, p.IV-5). In the partially mixed estuary, the tide is sufficiently strong to pre vent the river from dominating the circulation. :~'The .added turbulence of the • • tide does away with the salt wedge. The salt water is mixed upward and the fresh water is mixed downward. The difference between the surface and bottom salinities remains constant over ffiuch of the estuary. Seaward through the es.tuary the salinity becomes higher, (Schubel p.6). In a vertically homogeneous estuary, the tidal velocities are increased even more and if the estµary is wide enough, the interface between fresh and • salt water is completely gone so that the water becomes vertically homogeneous. The salinity increases seaward, (Schubel, p.IV-8). In the sectionally homogeneous estuary, the tide is so large it almost • completely overwhelms the effect of the river flow. There is the same seaward • increase in salinity but with the interface entirely gone. The salinity is homogeneous both laterally and vertfucally, .r schubel, p.IV-;8) . Sediments in estuaries are de~ived by rivers, shore erosion, biological activity, and by the sea. The sources of these sediments are therefore external, . • marginal, and internal. In some estuaries the sea has been shown to be the major source of sediment. Some of these are the Seine Estuary in France, the Mersey Estuary in England, Tampa Bay in Florida, the Rhine Estua+y.~ _;Ln.. Germaµy, • and many others. The mouths of many estuaries are :partially filled with sediments derived from barrier islands and the adjacent continental shelves. Most of these sediments are sand, and the evidence for marine origin is mainly textural • and mineralogical. These marine sands are de:posited as s:pfuts, barriers, and ebb and flood tidal deltas in the mouths and lower :parts of the estuary. The sea may also be a source of estuarine sediment because of the net upstream movement • of the lower layer which characterirzes estuaries. This net upstream flow can transport sediment up into the estuary if enough fine sediment is available. Probably only a relatively few estuaries have the sea as their major source of sed • iment, (Schubel, V.-4). In most estuaries, the major source of sediment is derived from fluvial sources. The amount of sedim.ent derived from a river depends on many factors, • including the flow of the river (mean, :peak, flood freg_uency, etc.), the types of rocks in the drainage basin, the climate of the drainage basin, and man. Large river flow does not necessarily call for high sediment discharge. Not only must • there be a transtporting mechanism, the:ie must also be an available supply of sed iment. Some estuaries in which fluvial sediments have been shown to be the main source of sedimentation are the Chesapeake Bay, Delaware Bay, the Mississippi: • estuary, and many others throughout the world, (Schubel, V.-14). Shore erosion of the margins of the estuary itself can be the source of sediment to an est~y. Not much has been said about this :process, but a detailed • examination of old and recent topogra·phic maps and ba thymetric charts can help in learning about shore erosion, (Schubel, V.-15) . .An:,.internal source of sedirr:entation is by biological activity. Estuaries • • support large popu·lations of plan.ktonic, benthonic, and nektonic organisms. They all contribute to the sedimentation, but are probably not the major source of • sediment. The main role of these organisms is in the agglomeration of fine suspended particles by filter-feeders, (Schubel, V.-16). The four types of estuaries based on circulation, ( the salt w2d.ge, the part • ially mixed, the vertically homogeneous and the sectionally homogeneo~s estuaries), possess d iff~.:?!'ent degr.ees of mixing. The different types range from river flow dominated to tidal flow dominated, depending also on the geometry of the estuary. • Changes in circulation patterns result in changes in sedimentation pattern. For example, the~type of sediment pattern in a salt wedge estuary is represented by • fine suspended particles brought in by a river which settle into the lower layer and brought back upstream by its net landward flow. These fine particles will accumulate around the tip of the wedge, and heavier fluvial particles which are transported along the river bed by creep and saltation will accumulate upstream • 9f the tip of the sea water wedge. In the partial)ymixed estuaries, fine sus • pended particles brought in by rivers settle into the lower layer and are carried back upstream by its net upstream flow leading to accumulation of sediment on the bottom. . _·.;:Because·:oft:~:the mixing~. which is more than in the salt wedge type, there will probably also be an accumulation of sediment in the water column. In • a vertically homogeneous estilm:y~.(.,the net flow is usually upstream on the left side of the estuary facing seaward and downstream on the right side, in the Northern Hemisphere. There is an upstream movement of sediment on the left side and a net flux of sediment seaward on the right side of an estuary, (in the Northern Hemisphere). In a sectionally homogeneous estuary, the tide is so strong that it almost completely dominates over the effects of a river. There is a slow net S·3award flow at all depths, and the most rapid sedimentation would occur where • the slow net seaward flow is interrupted by tributaries or obstacles,(Schubel, v.-15) . • Circulation; Influence on Organisms • Circulation plays a very important role in the ecosystems of estuaries and lagoons. They are the mixing place of two very different environments, fresh water and salt water, and thus environmental conditions are changing constantly. • An organism living in an estuary may experience daily, twice daily, seasonal and other changes in salinity of considerable magnitude. This variation in salinity appears to be the greatest hazard to life. • Many specie.s survive by resisting salinity change. For example, barnacles and burrowing animals can close their shells during the low salinity period, and open up again later. OvganrLsms may be able to live only in a certain areas • within the estuaries, such as soft bodied organisms which live in the upper tidal levels and are wetted only by more saline aaters. The: t:h.es of ·organisms which are adapted to estuarine environments by resisting salinity change are • called resistors. The most successful estua:c:Ine animals are those that have adapted to tolerate or accomodate themselves to the wide changes of salinities. These tolerant species are usually the lower groups of animals. The:.. salt content • of a resister~s blood is kept close to that of the sea, while the salt content of a tolerant species is kept close to that of the estuary. The degree of salinity regulation varies from species to species, (Loss, p.76.). • The complex sedimentation processes produce sediment patterns whiah also determine different types of environments. The nature of the substrate has considerable influence on the plant and animal inhabitants of an estuary. Pure • sand and pur.e mud present problems for some livir:ig~: oranisms. Mixtlires of sand and mud support more faunas. The muds of the bottom of estuaries hold more of the saline waters as the tides ebb. Thus bottom-dwelling plants and animals • that require higher salinities are able to exist farther into the estuary than similar organisms in the fiuctuating water above the bottom, (Reid, p.106). • • • Temperature The heat content of estuarine waters is derived mainly from solar radia• tion. Heat is also received indirectly from inflowing river water and tidal flow from the sea. If an estuary empties into a relatively deep sea, the temperature may be more stable seaward than near the upperrzone where the river temperature may fluctuate widely. Estuaries emptying into shallow sea zones have more stable temperatures in the upper. zone near the river. Seasonal temperature fluctuations depend upon latitude and other local • factors sucht,as water source, basin morphometry, winds and tides. For example, temperatures in the Sheepscot estuary of Maine range from about fr:ee.zt.rys to near 25 degrees Celcius in tha:,upper reaches of the estuary, while in the lower • reaches the temperature is about 15 degrees Celcius. These temperatures are determined mainly by atmospheric and climatological conditions, (Reid, p.135). Another factor affecting temperatures in estuaries is the flooding of • marshes and mud flats during hi~h tides. As the tide rises, the water of the estuary cover the marshes and heat is imparted to the waters. Temperature distribution in estuaries is mainly a function of depth • with the effects of stream inflow and tidal exchange. Furthermore, there may be a vertical temperature gradient with certain conditions of and sufficient depth. For example, with the cooling weather of autumn, the upper waters • cool quicker than the deeper waters, resulting in overturn and mixing. Density stratification derived from cold or warm fresh water flowing over the more dense salt water also contributes to vertical temperature differences, (Reid, p.126) . • Temperature has an effect on the kinds of organisms which live in an estuary. Temperature has0a.h.:,,affect on the organisms' physiological reaction rates, (Stevenson, p.11) . • Chemistry Every year million~.~ of tores of (j i s;:;;o-..:ed sol1iG a:ce pa,:.:~sed tlr :ough est-;.A.::<~~ies as r ivers make t heir way ~o the sea. As al l thi s material passes through the • • estuarine zone, it encounters the dissolved solids of seas water. An estuary is therefore a region of mixing between two envionments of very different chemical composition. • In sea water, sodium is the most abundant cation. Streams usually carry more calcium than any other element, and calcium and magnesium together make up a larger fraction than does sodium. In streams the anion sulfate occurs • ..?-•. in greater proportion that· does chloride, and in many cases carborlte does also. Offshore and away from stream influences, seawater has a nearly constant content. Sodium predomintes among the cations of seawater, making up almost one • third of the to.uu salts content, and chloride is the most abundant anion, making up over one half of the t;~r.ll ionic composition. Thus the chemical composition of estuarine water is derived from both•the .contribution from fresh • and salt water, (Reid, p.251). Between these two relatiyely uniform state there exists a considerable gradient in processes and conditions. The distribution of dissolved gases in an estuary is determined by • turbulence and current factors, bilogical activities, and salinity and temperature effects. A factor which is very influential in the distribution of dissolved gases is salinity. In salt water the solubility of oxygen decreases • as water temperature and salinity increase. Less oxygen can be dissolved in seawater than in fresh water. The importance of these relationships is not only the possibility of a considerable linear oxygen gradient, but also the • possibility of fi~ctuation associated with stream flood seasons and the inflow of large ~uantities of fresh water, or with dry seasons when tidal flow of sea water dominates, (Reid, p.219). • Furthermore, oygen varies diurnally and seasonally within estuaries. The ranges of the variation can differ according to type of freshwater source, the morphology of the estuary, _and the t'ffects of tides. For example, in dee-p, • • • 17 turbid estuaries lacking the contribution form an abundant bottom flor~, : _ .-· • diurnal oxygen pulses are relatively slight. Shallow, clear estuaries may • contain bottom growths of algae on which oxygen bubbles may be seen. Seasonally, the oxygen mctY be influenced by variation in river discharge, tide, day lengt~ and biological effe~ts. The solubility of carbon dioxide in estuarine waters is determined mainly f('> by the amount of seawater mixing with fresh water, and also by tevperature. • Some of the carbon dioxide in seawater is in the form of free gas and as • carbonic acid, but most is present as bicarbonate and carbonates. The presence of the excess bases in seawater, boric acid and its borates, carbonic acid and the carbonates, buffer the water against great changes in pH that might develop from the addition of acids or bases. t} • Since carbon dicYside uptake is greater in the presence of excess base, and riv.er::~water contains less excess bases than seawater, the~will ·be a lower content of free2carbon dioxide in the mouth of the estuary than in the upper reaches. Also, the free carbon dioxide concentration and pH should be more • variable in the part of the estuary that is dominated by river influences. • The quantity and quality of dissolved solids arid-·gases _dete2~miht.the· vat~ety and abundance of plants and animals. With dissolved solids, the chemical density of the environment of the organisms is a function of the total dis • solved solids. Plants and animals~..are adapted physiologically to these environ_mental density factors. Osmoregulation is the main factor in restricting organisms to the±r habitats. Also, dissolved solids influence the nature in • which the community relates to supply of nutrients and other important materials. Animals may be directly limited by the availability of a given dissolved substance, for example, animals bearing carbonaceous shells, (Reid, p. 226). • Flora and Fauna of Estuaries Because of the influx of Marine, fresh-water and terrestial components estullJ,y flora and fauna are very diverse, if not on a phyletic level, on • a specific level. Microflora Important factors of the microbiota of estruaries are chemical composition, • most important light, temperature, and toxins. P04 and N03 control the am ount of green plants in the system, and may be higher in estuaries due to run off from urban areas, agricultural lands, or from areas atop calcareous rooks. Inor~ganic matter· is converted to organic matter by plants and re . converted by bacteria and fungi • • ·1 0 e~.t:f1t.M._,J ~he first colfnizers of mud are~the Blue-green algae, Green algae, and Brown Algaes. All of these algae are important in the mineralization of organic • compounds. Their biomass can get so great it forms dense algal matts in which, under normal oonditions,biomass can increase five to six fold in twenty four hours. The almost .constant amount of biomass is explained by the large number of grazers that keep the population under control. Algae are part of the • organic detritus many animals depend upon for survival. Found within the first few mm of sediment are Euglena and Diatoms. These two microfloras are very important. Euglenas are believed to share in the • digestion of flocculated organic matter, along with the bacteria and cer tain Dinoflagellates. Euglenas are thought to migrate to the sediment sur face'fiuring the day and descend again during the night. Light intensity has been shown to play a key part in the migration. Diatoms are very abundant • in estuaries. They are found in all regions of the est .uary, all having some kind of adaptive mechanism. Those found high on high shores secrete a mucilaginous sheeth to protect them from drying out. Others are able to move quickly allowing fast migrations. Diatoms are i.mportant oxygen pro • ducers. They are also important in maintaining the food chain, being food for Protozoa, Turbellaria, Ostracoda, Nereis, and Hydrobia ulvae. Red Algae grows in a variety of regions within an estruary also. Some, likeBostrychia scorpioides grow on plants in lower reaches of estuaries. Others, like Catenella, grow in cracks between stones and in other well shaded areas. • -'19 All of the significant groups of fungi· ·~can be found in estuaries. Fungi seems to flourish in highly vegitated areas, the roots providing a surface • for growth. The species Mucor and Penicillium are most frequently found in bare muds. Dendryphiella salina and Ascochyrula obiones are found in more vegitated areas. Fungi play an important role in the decomposition of organic matter and the release of reducing substances. This cycle produces • an anaerobic layer of sediment about one to four cm in to the sediment, because of the consumption of available oxygen. Maorofauna• Macrofauna comes in two varieties, the grasses of a salt marsh and the trees associated with a mangrove swamp. Zostera is a grasslike perennial flowering plant which colonizes.·.more• marine areas in bare mud. These plants have rhizomes which branch out from the plant and produce more Zostera plants and help to stabilize mud banks. They are found between the half tide and low tide regions in an estuary• • A primary colonizer of mid-regions in estuaries is Salicornia. Their rooting system is very shallow and therefore these p~f'..s are found only in areas with very weak currents. Areas colonized by $alicornia are often rein • forced by algal accumulation which helps to slow tial flow•. • A more stable colonizer of mid•regions is Spartina. Spartina is a stout cord grass with a root structure ha~ing vertically descending roots and another series of horizontal root~xtending laterally and making them es p~cially well adapted to the soft sediments they live in, They, too, slow tidal flow and promote the accumulation of new sediment. Ruppia grow where tidal range is low and salinity is low. These slender· plants may extend into fresh water but are not colonizers. The waters, , . S&.~1 M l! l'lt· • Ruppia grow in must be permanent.· Also found in water with reducedAare species Phragmites comrnunis and Soripus maritirr.us. These tall marsh grasses are important communities at the head of an estuary• • In more sandy substrates the dominant grass is usually Pucinella, which may then be replaced by Festuca rubra landward. Behind the area dominated by • • Festuca, a mixt~re of grasses are found, the Thrift (Armeria Maritimal) ' Sea spurry (Spurgularia salina), Sea lavender (Limonium sp.) scurvy grasses (6ochlea.ria sp.) and sea arrow grasses (Treglochin maritima). • The Aster tripolium may invade areas of Salicornia. or may form separate zones. These yellow daisy floweres help to attract terrestrial insects to the marshes. • The tropical equivalent to a salt marsh is a mangrove swamp. The two most popular plants of this area are the Rhizophora -(red mangrove trees), a.nd the Avicennia(Black mangrove trees). • Red mangroves occupy the outer limits of the swamp and have large downward raching branches or rhizophores. and grow into very large trees. • The roots, once again, restrict flow and enhance sediment accumulation. Rhizophora seeds sprout before dropping off the pl~nt; this helps the new plant to establish itself quickly. • Bla.ck mangroves grow headward of the Red. These plants have aerial rootf1 which grow away from the plant underground for a short distance, then surface. The roots are equipped with projections which contain air cavities. There are two major associatio.ns of mangroves; The eastern association which is found from East Africa to Mala.ya and on to Australia, and the westexi association found in west Africa, and from Florida to Brazil. The eastern association contains Ceriops candolleana, Bruguiera gym • norhiza, Lumnizera racemosa and Nipa fruticans. The western association, listed by progressive proximity to land, may include White mangroves (Laguneularia racemosa) Button woods( Conocarpus erectus), cabbage palms (Sabal palmetto) and the strangler figs (Fiscus aurea). t Microfauna Th' most important oompon~nte of microfauna are the Protozoa, Nematoda, and Crustacea. Flagellates, bacteria, ciliates, rhizopods and other protozoa dominate the sediment-water interface. Along with the fungi, these plankton produce the anaerobic zone caused by the consumption of oxygen during the process of decomposition of organic matter. • SJ cni·ates are classified as mesoporal or mioroporal, the former living in sand with an average grain size of 0.4 to 1.8 mm. The latter, between • 0.1 and 0.3 mm, euryporal live in either. Cilicates are not found only in the substratum but also inhabit the film of bacteria, diatoms and algae that cover the sediment. Bacteria, diatoms and organic detritus comprise the food oili· ates live on. Many cilj ;ates are specialized • feeders ea~ing ) only the filaments of green al~ae like Nassule citraea, • or some eating only bacteria. Some are preditors, preying on other protozoa such as Lacrymaria. Forams are mostly marine species but a couple have been able to adapt to fresh water. They catch food with their pseudopodia. Trachoammina inflatais abundant in the marshes of the Gulf of Mexico. • The Protohydra leuckarti is found from the Gulf of Finland to the Bay of Archacron, has been found living in sand and mud, but prefers a • mixture of the two. This hydroid grows to about 1 mm and can live in salinities that range from).8 to 30;h. They feed primarily on copepode and nematodes • There are three orders of micro-turbellarians found in estuaries; the acoela, which is the simplest, the Rhabdocoela, and the Alloeoooela, • which is the most complex. These small flat worms are mainly carnivores although a few are herbivores. Some, like genus Convoluta of the acoela, have a symbiotic relationship with a greem algae• • Nematodes are very important in estuaries. Most are found in the top 4 cm of muddy substrate, and seem to decrease as you travel from the .mid estuary toward the head of the estuary. Nematodes are divided into four categories on the basis of the morphology of their feeding• st:r-ucture. The two most important types o.f Ostracode¥ound in brackish water are of the families Cypridae and Cytheridae, the former being a fresh weter qroup • and the latter being mostly marine. Bottom dwelling Ostracods are thought can to be scavengers, feeding on algae and detritus material. Ostracodt live in salinities between o.5%oand 20~• • • Perhaps the most important member of the permanent pla.nkters are the Copepods. They are thought to be wandering scavengers, feeding on detritus and small bits of algae. Copepods are found in a varitey of salinities, some being restricted by salinity and others, like Horsiella • brevicornis are capable of living both in sea water and in fresh water. The type of sediment plays an important part in the distribution of Copepods. Some burrow, some live in plants, and some just skim across the surface of a sandy bottom looking for food. • in the sea at great depths and in the Halacarid mites are aquatic and live intertidal zone. 1rbe two main sub-families of halacarids are the Rhombognathinae, which are scavengers and carnivores. Rhombognathinae has a black pigmentation and is common. in the upper reaches of an estuary. Halacarinae feed on very small microfauma or the eggs of Copepods and annelids. • Mysidacea are the migrating~plankton! They remain close to the bootom during the day and migrate to the top under certain condition. These pseudoplankton resemble small shrimp and eat· a variety of food ra.ngning from diatoms to larger dead amphipods. Biologists seem to disagree • on how to charact3rize these small creatures. Three classes of Coelenterates are found in eetuaries; the Hydrozoa, scyphozoa, and Anthozoa. The only true fresh water Coelenterates ·and • most .of1the brackish water coelenterates are of·.. t-he clasf\HYdrozoa. Cor. hy d . dClf\dcan survive 1r.. k. h wat er an dylophora is a gymno blastric rio . brao is d ca..~ live in fresh., water if it is well aeriated. Laomedea loveni is a truly euryhaline hydrozoa and can survive in salinities that • range\from 1 to 35%r-Very few .A.nthozoa ca.n survive low salinities. Several marine species, such as Actrinia equina can tolerate salinites as low a~ 8%a, but this water must be stable. · They cannot tolerate • continual change. None ha~ become adapted to fresh water. As previously discussed, many Turbellarians are considered microfauma, but some are too large to be characterized in that class. Procerodes lives in the small stre ams of the intertidal zone. During low tide this flat worm is subjected to fresh water and during high tide it is subjected to .·salt water. Uteriporis vulgaris lives in the mud at the bottom of salt marsh grasses and during the d~y is ususally subjected to damp air. no water, for several hours. When it floodS or there are heavy 53 • rains, this flat worm must also tolerate very low salinities. Of the Annelids, Nereid is by far the most common. The best studied Nereid is the Nereid diversicolor from England, This species spends • its entire larval life within the surface mud layer: and never enters a Adult nereids can tolerate low salinities, but planktonic stage. their larvae are restricted to higher salinities. Nereid feed on things as large as dead young mullets or as small as suspended particles • filtered from above the sediment. Copepods, ostracods, nematodes, forams, diatoms and various organic matter can be found in smaller Nereids• • Lugworms of the genus Arenioola, burrow into the muddy sands and mq· stay there for several months. Larvae of the species Arenioola marina are able to swim but rarely ever do, and they never enter a planktonic stage. Many other species of worms are found in esturaries, a few genera of • which are Nepthys, Phyospio, Scoloplos, and Heteromastus. The latter two are found closer to the mouth of estuaries. • Nemerat~esemble · elongated flatworms and are also found in estuaries The best known is Lineus ruber. It is a carnivore and is found from found in salinities of Alaska to South Africa. It is about 8~• • • Estuarine Eotoprocta resemble colonial hydriods but they are actually coelomate animals. Viotorella psvida is the most widely spread. It is found fro~ Egypt to Japan and from Australia to Brazil. It can cope with salinities which range from 3 to around 27~. One species, Membrainipora crustulenta, is of great annoyance to oyster cultivators. These form encrusting colonies and when too abundant occupy all abailable stones and solid objects, leaving the oysters homeless• • O~e of the most abundant families Gastropods are plentiful in estuaries. ·ing is Hydrobiidae. Hydrobidiie species prefer different salinites rang~·= from 0 to 33~. Habitats vary from heavily vegetated to bare exposed areas and the food they e~ depends upon the area in which they live.• • Hydrobia ulvae has a unique disperal mechanism. It secretes a mu.c.us raft which enables it to float to different re~ions in the estuary• • S"I The mucus also traps small particles of food,which it then eats. Truncaltella subcylindrica is a small hydrobiid associated with the high shores near the -mouth of a.n estuary. Two species of periwinkle travel well into estuaries which have a rocky shore. niey are the Littorina saxatilis and the Littorina littorea. Littorina saxatilis is especially adapted to life in an estuarine environment. It can survive without food for weeks. It can live permenently for weeks in salinites ranging from 8%oto greater than 34~~or survive several days submerged in fresh water. This gastropod is able to withdraw into its shell and close off the ambulicus with its operculum. Two small species ofpudibranch gastropods are found in some European estuaries. One species, Alderia modesta can be found off the California coastline and up into Canada. Limaponitia depressa is the other European species.~ Mytilus edulis is one of the more common Lamellibranches. It attaches itself to any ·type of solid bottom, a.ften attaching itself to bouys~ marking channels where tidal flow is rapid. Growth of Mytilus larvae ia dependent upon temperature, food, a place to attach and salinity. Low salinities tend to cause a slowed growth rate. Primary attachment i s made by the foot of juveniles and is made permanant by the secretion of If after a . ~ 1e . unha.ppy "th byssus threads. short time,..the young muse 1s w1 its placement, it can re•orb the threads and move to a new home with the help of the next tide. Low shore intertidal mussles which stay submerged are able to feed continuously and are therefor at an advantage. Oysters, of the family Ostreidae, can only secrete from their byssus gland once. If they become dislodged, they cannot reattach themselves and will eventually die, The two genera most common in estuaries are the ~Ostrea and the Crassostrea. Crassostrea seems to be able to tolerate lower salinitie·s than Ostrea. The latter" not being able to tolerate salinities less than twenty percent for extended times. Most oysters begin as males but after freeing their s perm they change into females. Some 1·/ill change back into males after freeing the eggs . 1rhis can happen repeatedly. Mussles and oysters are epifaunal , but cockles are in~aunal burying them . e :ed and a .es .e s selves shallowly in muddy sand or course gravels. Cockles are normally inter~idal, but will live submerged if possible. One factor which may enhance colonization of intertidal areas is the whelk, it is a subtidal animal and preys on cockles: . Scrobicularia is a common cockle and can live as ·far down as thirty cm into the sediment, shooting its inhalcmt si?hon to the surface to collect food and to bring aerated water to the mantle cavity for respiration, The soft c_larn r~lya arer..t:rit..:i. penetrates UVi>er estuareis where flagellates are abundant. Salinity seems to slow the rate of feeding of Myas. Larvae of Mya tend to spend about two weeks in thewlanktonic stage before settling. One fe~ale Mya may produce 3,000,000 eggs; but mortality rates are high due to the ease with which larvae are swept to sea. Barnacles seem to be well adapted to an esturines varying conditions. D~ring unfavorable conditionc barnacles will retreat into their shells and close themselves off from their surroundings by shutting their scuto-tergal valves. Barnacles may close their shells when the tide is out to keep from drying out or during periods of very low salinity. Larvae are maintained as eggs untill they hatch into the first of six nauplar stages. During this stage they are planktonic for several weeks. Diatoms and flagellates are common food for barnacle8. Isopods seem to have been developed especially for esturine environments • Isopods have walking legs and biting mouth part~. They carry their babies in a brood pouch, until they emerge as miniture forms of their parents. The most primative group of Isopods are thought to be the Asellota. lh~y are found in very deep parts of the ocean, all the way into fresh water. Species of Faera are usually abundant in estuaries. All of the species of the genus Faera are considered euryhaline, and can be found living in ~:;tony areas• .F'labellifera are swimmers as opposed to crawlers. One genera Sphaeroma ha;:· the ability to curl up~thus discouraging priditors. The ability to roll themselves up a,lso helps to keep them from drying up if the swamp marsh evaporates. 1 Sphaeroma have a wide variety of salinity tolerences. In some areas • sequences of species can be traced along the length of a..Yl estuary. Another flabellifera is ~"'urydice pulchra. This species can perntrate a long way into estuaries. It spends most of its time buried, but ascinds to the surface at night to become planktonic. • Cythura are burrowing isopods living in the intertidal estuarine muds. Cyathura polita i s found in abundance in the Gulf of M~xico associated with the Spartina zone, Cyathura polita eat s organic detritus, diatoms, • dead fish, and will sometimes attack and kill small gemme.rids. Va}viferous isopods and Oniscoidea i s opods are also found in estuaries. Amphipods are very i~portant epifaunal anirnals~the most popular family • being Gammaridae. The species of this family range from salinities above 34'%ato fresh water. One genra, Garnmarus duebeni can actually leave its salt water poo.l and crawl across damp land. • Corophirm volutator is the best known Amphipld. It burrows in fine sand and mud, ; and lives in a range of salinities. None are associated with fresh 'triater. Food for Corophium consists of organic detritus and microorganisms. Corophium consists of organic detritus and micro • organisms. Corophium crassicorne are assiciated with Zostera zones , burrowing into the soft sediments . • Decapoda Natantia includes decapods that u s e their taih; for locomotion, of which shrimp and prawns have many representatives which live in estucries . The Texas shrimp fishery is dependant upon Penaeidae, which pr ef er waters with low s~linities. Five species of Palaemonetes live in the brackish water of estuaries. The common shrimp (Crangon vulgaris) • mi Gn ite s out of the estrary during the vinter and returns with the sprinf~; . Entuari ne crabs have been placed into zones.· In the upper zone~ ·iocated above the highest wrnter level i s the Sesarmine zone. Helice har:wellianus • e.rd Sesarma erythrodactylv. dominate this zone. The second zone, Cc:ypokine znne, extends from t"he high water lev.sl to t he mid-tid-e region. Uoa longidigtum and Heloecius cordiformis are dominant here. The third t zone, the Upper Macrophthalmine zone extends from mid-tide regions to low water neaps. Euplex tridentata dominates the lower rea ches, with • S7 Cle:i.stost.oma meneilli becoming dominant upstrea.m.. The fourth zoTie ie· located below the low water of neap tides. The Lower Macrophthelmine zone is soft mud where Macrophthalmus setosus b6.rrow into the soft mud • being the most dominant by far. These zones are most clearly developed in· the lower and middle sections of estuaries. Fish found in egtuaries may be grouped according to their habits and • how long they remain in the estuary. Some fish of the class Teleosts a.re true esturine species such e~o flounders and the gobies. Some fish migrate in to the estuaries for a short time late in summer and late in autumn. the horse mackerel migrates in this w~y. Some fish migrate from fresh • water to estuarys to breed, such as white fish. Trar)sitory specier; just pass through estuaries on their way to another destination. Common exar:iples of these are salmon and the fresh water eels • • He.gfish and Lamphreyc,which belong to the Class Cyclostome migrate into estuarys to spc:nm then leave again. Lampetra planeri lives its whole life in fresh cater. After hatching the lamphye;1 head to sea., where )' • they look for shad and salmon to attach themselves to. After feeding on the living fi sh for a year the lamphrey migrates back to the estuary to spawn and die. • Some larger Elasmobranchs can survive t·he lo\\ salinity of estuarine waters. Sharks are able to enter estuaries . Bull sharkf~ of the Southern U.S•. and Zambezi sharks of Asia, can both be found as far as fifty miles up~ stream. The large Sawfi~h, genus Pri stio, can be found in estuaries. • This fish uses its saw to plow through sediments, unearthing plenty of • food, It may also by u~3ed to ;::.l r.:i.sh through school:.:~ of mullet. Wounded fish are then eaten at the disgression of the Sawfi3h. Because of the plentiful food supply c.nd limited coverage for preditors • many bi~ds live associated with Estuaries. 1rhey may be perma:nant residents like the corr.10rants, Aerons and Kingfishers, or migrate in like the ducks and gee::;e. Some of the e .3turine birds feed on fish, like the pelicans. Others wade into the water to dig up invertabrates from the s~diments • These birds l:i~e the sandpiper, the God'd ts and. the Curlew, all have bill siz·es adapted to the kind of invert2.brate they e.re looking for. Herons e,nd storkes 1rn,de into the Kater c:md ~;rd t for ~m u::1~u~~pecting • fish to come close enough to be ye.nked out of t he i;-,-ater. Kingfisher s and Pelican::i prefer to dive right into the liater and catdh the fish with their beaks. Flo.m.lngoer~ r-~re filter feeder~~ eating diatoms and bluegreen algae. ~~e2. Gull::.1 are uc.uall~,r sccvernger:~ , but some 1dll ea.t anything they ce.n ca tch and kill. • • ~::onie mammales may enter estuarier! 2.lso. These mammals all belong to • the orclerr~ Cetacea, Pinnipe.re found in Chinese, Indian, African and America,n estuarier:. Porpoi ::;es and Sea lions can • be found in Japanes e and Arnericn.n ectuHriec. White shales and many sealc can be found in Artie estuaries. Sea cowf; can be found lolling on the shores of African e.nd Aur-:trailinn estuaries. • Man has had a negative effect on estuaries in a variety of ways. 'I1he mo~ .:t I 1 obvious of which is chemical pollutant8. l1he reduced flow in: er:tuarie~~ causes settlement of sedimentr:. Me.ny chelllical toxin~ and tmspended wac teu settle along with the naturally settline sediments. Accumulation of theoe tox.ins can have devista ting effects which can reach [J,11 the we::/ I up the food chain to man. 02 rn2.y be reduced killine off plankton., the ba~'.e of the food web. Invertabrs.tes may absorb these toxins into their tissue~.; rendering them unfit for conffur.~ption. Fish may eat these contar:1inc.tea. inve1"tabrates. 'fhis nc:ti-::es tho:-;-! unfit for human use a.nd often . ~ .. ' • leads to cancer in indivio.ual~::i . Pollution ma.y be cau~cd by the accur.~u lo.tion of hee.vy :netals such as ag, Ni, Zn,Pb, Cu and Cr. 'l1her:.c CC1.n inhibit i:liotos:yntheL~i;; and can even cauc-:e brc-i..in hemorhaging in ~~ome fish. Org41.:nic chemicals st1ch ar:; J)J)'r and. PCB are not biodegrndable, c1nd even a.r; s;i12.H a pcrticn n~i 5 :ppm render fi~h unfit for hur:ian consumption. Cf course,oil is very clow to decornp9se. A film of oil on the surfnce i~ ~ :ufficient barrier to stop the exchange of o~rgen bet1..;een the iH?.ter ano t~1e atmos1)here, which decrea:::;e s de:c; r:.olved oxygen in the wc.ter. Direct • contact with cil kill::~ m<,ny fi'.3h tJ.nd other orga.nimns. Dome s tic wastes • lead to a condition called Eutroph5cation. Excessive enrichment of No3 and P04 cause the biostimulation of obnoxious species of phytoplankton which replace the normal stock of phytoplamkton. Domestic wastes also • lead to the over consumption of oxygen, because of the over activi ty in degra.deation by bacteria. Thermal ·:polution causes a decrease in the amount of dissolved 9~ aiid increases the matabolism in many organisms. Radioactive contamination causes cancer and mutant offsprin~• • I'·lnn also uses estuaries for shipping and transportation, .for biological nnd mineralogic resources, and for recreational ~urposes. These activit ies change natural cycles and eliminate many habits of estuarine animals • • The building of bridges, houses or industry may interfere with tidal flow-, changing the zonation c:md distribution of animals. Eotuaries mu d -oe protected and managed if they are to remain the via.ble and multiuse • onvironmonts t hat they are • • Bibleogra.phy Barnesj R.S.K., Coastal Lagoons, Cambridge, Cambredge University Press , 1980. Barnes, R.S.K., Estuarine Bilol;gy, London, Edward Arnold (•Publishers) Ltd., 1974· Barnes, R.S.K., :_a.nd Professor J. Green, The Estuarine Environment, • London, Applied Science Publishers Ltd., 1972. Colwell, P. R. and T. Harold Stevenson, Estuarine Microb;_~:.LX!.£~' ,_ Columbia, University of South Carolina Press, 1973· Dyer, K.~ Estuaries: A Physical Introduction, London, John Wiley a.nd Sons Ltd., 1973· Dyer, K.R., Estuarine ~drogtaph~ and ·Sedimentation, London, Cambridge University Press, 1979• Emery, K.o., A Coastal Pond, New York, Americal El sevier Publishing Company Inc,, 1969. Ganapati, P.N., Esturine Pollution, Ed. C.V. Marine Sciences, University of O.:>chin . • Green, J., The Biolosv of Estuarine Animals, Washington, 1968. Kurian, India.na Department of 1977• Seattle, University of • Johnson, T. w., Jr., ttThe Estuarine Mycoflora" Ed • G.H. Lauff, ~~ Washington D. c., American Associ · ation for the advancement of science 1967. Kennedy, Victors., s., Estuarine Perspectives, Cambridge, Academic Press , 1980. Ketchum, Dof'twick H., "Ph;ytoplapk.to;i Nutrients in Estuati~,E.'" .Ed. G. H. l miff • Jiif!-f.:11a.d .E>P, \·l :'.l.e1d •k Lr111 ~1 1_!),, Ahfb. J'i 01:l•• A~ti1~ni ;, Li ci;1 f 111' Ilie Advancement of Science, a967. Kha.juria, H., On Esturine Ifammal n, Ed. c.v. Kurian, Indiana, Department of • • (p() • Kurian, C. V., Contributions to Esturine BioloP.:Y, Inc.i2nd, 1Je1n),rtment of r·fa.rine Science:;'. Univer~:i -t~r c;f Cochin, 1977. Lad.key, J. B., "Nicrobiota of Ec;tuarie~1 " C?.nd Roles, Ed. H. G. L.~uff, Estuaries, Ar:ierican .A.csocta tion for the .AC.vancement of Science 1967. Lose , G., Estuaries, ~ichigan State University, 1967. • Reid, George K., Ecology of In1 o.nd. Waters 2..nd Esturies, New Youk, Reinhold Publishine Corporation, 1961. Reid, George K., and Richa.rc~. I;. ·wood, Ecology of Inl2.nd We_ter:::; and l!~::~tuc..ties, Second Edi tion, Ne1; York, Tilton Eciucationnl Publishers IncQ., 1)61. :i.hley, Go~don A., "Plan!-;.:ton of :i~ctuaries", r~d. G.EI. Lauff, Estuaries, • Wo.shington D.C., American Association for the Advancement of Science, 1967. ~:.chubel, J.R., The Estnarine environment, EBturies and Estuarine Sedimentation, Wachincton :D. c., Afl\er~can Ge~~9tt;0Qlt; Inst~, tlilte. 1971. Southward, 'A, J. Life on the §ea-shore,jI-fo.rvard, Harve.rd, UniveTsi ty • Press, 1975 • • • • • ~-Wet ~case" --./ -··. Low wa:er • ' I \~~z;l • Dry season Low water Wet season. High water Dry season High water s 20 25 30 • -~ D D lntermed.ate [ill • Fi("ur( 4. n· iagrammatic cross sections of the middle reaches of the four estuarine Figure JO. Salinity variation in a hypothetical estuary with a stable salini• types defined by Pritchard ( 1955) gradient and large tidal range. The two vertical lines represent the extreme mov ments of surface water with a salinity of 1sr00 u I ~ ,, Mid depth I,..._ • \-QJ :~ ..., ___ ,, 0.. /I\,,·,,.,..., I .... r \I I v ~ I I \ \ l ~e 0 f,. \ .. ! CJ t > • v .... ,,."1 c \ ,_,,, ~ ,_ \ ~ -" ::> ~ u ~~ • E c :·:rl ~ .,. 1 ~ ·-'"1 I ~ LI (\ • I I ; I I \ r ! \ ; :..' ,' ~--,,;__' l \', Hw L\V • • 1 t -·>~:,,----~~=~~:~l~;~~;;;~n~::=-=·-~.~~~=-~r~/;~~~~;;,~~~~~;~;f~~i~~l;~~~i;~,i~;,~f: =~~ I ::~~:;uacy --~S~~:---~~::~,]1{t+~_ · ~·---_ • ~~:~:=~.::an~ali1~ities_____ _ -·· i l J • Upper Reaches 5 -18 __L mesohaline mixohaline !_j T"n\Ldd'f boH--cilY' ''5\m...> ~olY\0\1(..fV\uv-. true . Middle Reachcsn _ 1 18 -25 polyhalme estuarine ~'1/1.u.uki"" ""to-~t" \h~() ~0~\--. t t°1An.1!°?'c::.... Lower Reaclles 25 -30 po.lyhalme I I~t~ " , ~\. \.\~ '(Y\~~e.n~ . .Mouth 30 -40 euhalmc stenohaline euryhaline migrants.~ .. ·······--·-·-_ . ··-·. ·----····· --··----. ··-· ·-------------------------···---~~~arine___·------~~~~~~--·-------- f • • (curlew \• • I Cardi um SI j • Jii I Scrobicularia ) -, • ' ........... • Figure 94. Diagram showing the length of bill in some common waders in relationto the burrows of some common mud dwelling invertebrates. Most waders canonly catch Arenicola when it ascends the tails shaft in order to defaecate. Largespecimens ofScrobiadaria are beyond the reach of nearly all waders • • • • • • • Figur1 17. Simplified diagram of plant zonation in the intertidal region ofa British estuarine shore. There arc many variations of this zonation. Some of the zones shown may be absent and additional zones may be present. The diagram is based in part on the sequence found in the Gwcndraeth Estuary in Wales • Salting c!d 1 Mud flat • • • H Salicornia ~~Halimione tlSuaeda River itffo,111f1ut//Ju Puccinellia 1 and general salt marsh • .llUJ.W.W..U. Festuca Fi;:ure 18. Three transects of the plants on an estuarine shore. The presence of a creek interrupu t~c ~onation and inter· poses a band of Ha/irniont. The three sequences are based on parts of the Gwendraeth Estuary, but s1m1lar sequences may be found elsewhere with local variations • • • • D • Figure 66 Estuarine Foraminifcra A, Lagma sul.cata. B, Ammonia beccarii. C, Elphidium striaw-punctata. D, MiUiatntnd,_ fusca. All are slightly less than 1 mm in maximum dimension i • • • Figure 15. Two estuarine diato~ A, Plrurosigma cu.stuarii, the length varies between 84 and 148µ. B, Surirella gemma, the length varies between 72 and 140µ • • • B A !-:<:u r!' J4. A, Tintinnid (Protozoa: Ciliata), total length about lOOJ.L. B, Synchaeta sp. (Rotifera), length about 240µ • • • • • Fip123. Lateral view ofadult female of Neomysis integer (Peracarida: Mysidacca). Actual length 17 mm. Notc:the broocl:t>ouch bulging behind the thoracic limbs • • • • Figun 22. Adult female of Cyclopina nor.xgica (Copcpoda: Cyclopoida). Actual length 1·5 mm (after Sars) • !-r..,· rm ~"I. Adult female of Eur;·t.mwra hinmdoidts (Copepoda : Calanoida). Actual length I· 7 mm (after Sars) • F:_t;urr 33 . . -1renirola marina (Annelida: Polychae~i , actual length 16 cm • • Figure 32 . . Nereis diversicolor (Annelida: Polychaeta), actual length 10 cm • ~- Figure 3I. M etridium schilleriar.um (Coelenterata : Anthozoa), actual length 12 cm (after Annandale'. · ~" , t . . /~/ ~ ~~ I f"t{'UTr 68. Prochromadorella bioculatll, a nematode capable of living in fresh and brackish water. Actual length O· 7 mm I Prosobranr:h1a), <'1g Figure 38. Litumr.a littorea (Gastropoda, ' "actuaJ h · ht of sheJl 26mm I B Fi;;ure 41. Mytilus edulis, length of shell about 6 cm; note the byssw threads whi anchor the mussel to a solid substratum Fir:im 40. Small estuarine nudibranch~ : :.~. ~;•. 1.·(;11 d~fl-:-t.~.r. ... ~. lci)r.,..~!~ :\1 1· fllt<" • • Fig lo. Stru..:tural and funct ional attributes of salt -marsh ect)~:-s tem (modified from Lugo and Snedaker. 1974). • Productivity Estuaries are very productive ecosystems, as indicated in • Fig. 11, next page.(J9). Mangrove is perhaps the most productive of the estuarine systems, however transfer of energy is much slower than in an estuary based on algal production. This is • crucial in understanding the effects of man's input to and use of the ecosystem. Tropical estµaries are also highly productive of fish and • serve as overwintering and food niches for birdso It was estimated that in 1970, 1 acre of undisturbed, southern Florida estuary would yield approximately $8,000 in commercial fish products over twenty years,(40)o • • Starting / Coral reefs (optimum nutrients) Fertil~eStuaries Ric}.forests Fertile Gr&Mlands al@el culture • agriculture / Polluted Ponds streams Terrestrial ~ succession --Swamp Rich lakes waters --Succ~1on in Oceans boiled hav / . Fig. 11. Relative productivity Poor lakes of various ecosystems, Des/ts Raw showing the high production sewage V of fertile estuarine I 0.J I 10 100 systems. Community respiration. grnlm2 /day Uses Rhizophora mangrove wood has been used for many things over the years, including tannins, dyes, timber for posts and firewood, and medicinal purposes.(41). The mangrove enviroment may also serve as a shoreline stabilizer. Mangroves have been transplanted to Hawaii for this pnrpose of erosion prevention.(42). Estuaries have commonly been used as a natural sewage treatment system, however care should be taken in this type of endeavor, But perhaps the greatest value of estuarine systems is their function as nursery grounds for many aquatic species of ::-I: r . rr'> o commercial importance.Valuable oyster 1 n .and · crab populations are regularly harvested from the estuaries. In the future, mariculture may play a much larger role in providing our food supply , and estuaries are an ideal setting for many types of maricultureo A more complete understanding of calcareous(tropical, subtropical) estuarine ecosystems is needed if we are to fully utilize such a valuable resource without destroying it or • • • • • • • • • • • doing irreparable damage • REFERENCES (1) Rodriguez, Gilberto. Some aspects of the Ecology of Tropical Ecosystems. InsGolley and Medina. Ecological studies-T-ropical Ecological Systems. 1975, J90pp • (2) Stephenson,T. A. and A. Stephensom.1950. Life betweennTide Marks in North America.I. The Florida Keys. ~· Ecml.)81354-402. (J) Gross.1972. Oceanographya A View of the Earth.p.262. (4) Phleger, F. B. 1969b. Some general features of coastal lagoons. Ins Castanares and Phleger.Coastal Lagoons. A Symposium. Universidad Nacional Autonoma de Mexico, Mexico pp.5-26 • (5) Rodriguez, Gilberto. See ref,(1). (6) Davis, J. H. 1940. The Ecology and Geologic role of Mangroves in Florida, Carnegie Inst.Wash. Publ. No, 5171 JOJ-412 (7) Horne R. A. 1969. Marine Chemistry: The structure of water and the Marine Hydrosphere. Wiley Interscience, New York. 568pp. (8)00rr, A. P. and F, W. Moorhouse. 1933. Physical and chemi:al conditions in mangrove swamps. Great B:irrier Reef Expedition 1923-1929, Sci. Rep. 2: 102-110. ( 9) rcetchum B. H • 1967. In: ~odriguez. p. 327. See ref. (1) (10) Daiber, F. C. Salt Marsh Animals: Distributions related to tidal flooding, ~alinity, and Vegetation. In:Chapman(:Eclitor) 1977. Wet Coastal Ecosystems.pp.79-106. ' I E. J L:.(lLll~)-~~. U..,..1:.r"l'll?lf~,_,1'!r.:0~t:-..... ' (11) Kuenzeler, E. J. Mangrove Swamp Systems.In. O:iom.1974. Coastal Ecological Systems of the World. pp. 346-371. 12) Kuenzeler, E. J. See ref. (11). 13) Chapman, V. J. 1975. Mangrove Vegetation. Cramer, lehre. 425pp. 14) Rodriguez, G. 196J. The intertidal estuarine communities of lake M:L:-acaibo, ~ Venezuela. Bull. Mar. Sci. Gulf Carib. 13: 191-218. (15) Bowman, H. H. M. 1917:-Ecology and physiology of the red mangrove. Amer. Phil. Soc. Proc. 56: _599-672. (1~1 Davi~. ~Jr. 1940a. The ecology and geologic role of mangroves in Florida. Carnegie~· Wash., Q. Q. Pub. jlZ. Tortugas lab. Pap. 32: 303-412. (17) Scholander. et al. 1962. Salt balance in mangroves. ~Physiology 37(6): 722-729. (18) Thom. B. G. 1967. Mangrove ecology and deltaic geomorphology: Tabasco, Mexico. .:l.· 12.21·, 55: JOl-343. (19) West, ~. C. Tidal salt marsh and mangal formations of middle and South America. In: Chapman(Editor) 1977. Wet Coastal Ecosystems.pp.193-211. (20) Chapman, V. J. 1976. Mangrove Bm-iogeography. Er.2..£. ~· Mangrove Honolulu, 1974. vol.l. Univ. Florida. pp. 3-22. (21) Iavis. 1940a. See ref:-('l'b). (22) Taylor, W. R. 19.54. Sketch of the character of the marine algal vegetation of the shores of the Gulf of Mexico.p. 177-92. In: G:ilstoff~.filiitor) Gulf of Mexico, Its origin. waters, and marine life.U.S. Fish. Bull. 55(89): 177-92. -- (23) Post, E. 1936. Systematiache and pflanzengeographische Notizen Bostrichia-Caloglossa-Association. ~· Algol. 9:1-84• (24) Eiebl, R. 1962. Protoplasmatische-okologische Untersuchungen an • Mangrovealgen von P0erto rico. Protoplasma.55:.572-606. (25) Kohlmeyer, J. 1968. A new Trematosphaeria from roots of Rhizophora race~osaMycopath. Mycol.~. J4: 1-5.Iavis. 1940. See ref. (6).Freyburg, G. ~m V. 19JO. Zerstorung and Sedimentation an der fungrovekuste, Brasiliens. leopoldina. 6: 69-117. • West, R. C. See ref.(19). Ro~riguez, G. See ref,(l). ~~~l Da1ber, F. C. See ref.(10). h1) Rodriguez, G. See ref. (1). (J2) Fhleger, F. B. Soils of Marine Marshes. In: Chapman(~itor) 19/7. WetCoastal Ecosystems. pp.69-76. • (JJ) Macnae, W. and M. Kalk. 1962. The ecology of the mangrove swamps at InhacaIsland. Mocambioue. J. Ecol. 50(1): 17-J4.GrosE. 1972. Oceanography:-A View of the Earth.pp. J90-J9J.~~~ Teal, J. M. 1962. Energy Flow in the.Salt Ma.rsh Ecosystem of Georgia.Ecology. 4J(4): 614-624.()6) Reimold, R. J. M:i.ngals and Salt Marshes of Fastern United States. In:·Chaprnan~Editor) 1977. Wet Coastal Ecosystems.pp. 157-161+. (37) O:ium, W. E. 1970. Pathways of Energy Flow in a South Florida Estuary.Ph.D. dissertation, University of Miami. 162pp. (33) Lugo, A. E. and S. C. Sneda~er. 1974. The ecology of mangroves. Ann. ~·~· SyEt. 5: J9-64.(J9) Pianka, E. R. 1978. Evolutionary Ecology 2nd ed. Harper and Row. New Yor1<. p. 64. (40) Rol:as, A. K. 1970. South Florida's mangrove-bordered estuariies: their rolein sport and commercial fish production. Univ. Mia~i See Grant Inf. Bull., No. 4: 28pp. ----- (41) Motton:-:r:-F. 1965. Can the red mangrove provide food, feed, andfertilizer? Econ. Bot. 19(2): 11J-12J. • (42) Walsh, G. E. 1967.An"9ecological study of an Hawaiin mangro11e swamp,p. 4204Jl. In: G. H. lauff(ed.) Ef:,tuaries. AA.AS Pub. No. 8~. • • • I. • II. I I I. • IV. v. • VI. VII. VIII . • • • • • • 5. The Benthic Continental Shelf Ecosystem Lisa Richards Elizabeth Andrews Introduction Description A. Physical Processes B. Chemical Processes c. Geological Processes Benthic Fauna and Flora Benthic Energy Flows and Productivity Benthic Continental Shelf Resources Man's Impact Conclusion References 9tJ • • 5. THE BENTHIC CONTINENTAL SHELF ECOSYSTEM LISA RICHARDS ELIZABETH ANDREWS Introduction I Major features of the earth's surface are it's co ntinents and ocean basins. The broad zone of contact between the continental and o ceanic domains is the continental • margin. Important elements of the continental margin include the outer shelf, the borderland, the marginal plateau, the slope, the base of the slope, the rise, and the marginal • trench. Landward from the continental slope is the continental shelf (Fig. 1), a gent ly seaward-sloping submarine plain bordering the emergent continents and extending from I the shore to the shelf edge. Continental shelves range in width from a few to more than a thousand kilometers. Among the worlds most extensive shelves are those of the Arctic • Ocean off Siberia, the Bering Sea off Alaska, the coast of China, and the Arafura Sea off Australia. The Sunda Shelf of Indonesia, the Atlantic Shelf off Argentina, the shelf • off Eastern Canada, and the northwestern European Shelf are, but a few more examples. On the average, the shelf edge lies 130 met ers below sea leve l and can range anywhere from • a few meters to 600 meters as is exhibited in the Arctic Shelf off Canada. The average gradient of the shelf is on the order of 2 meters per kilometer. The water temperature • of the benthic shelf regime varies with depth and latitu de. • • 3 • large-scale meandering of the currents (e.g. Gulf Stream). The velocities of these currents ranges from a few cm/sec to more than 200 cm/sec (Johnson, 1978). The stronger cur • rents tend to cause erosion, while the weaker currents transport suspended sediment. Tidal currents effecting the benthic ecosystem • i.'.t are prop~gated as waves deep in the ocean basin (cooscillation). The magnitude of the tidal currents is determined by the physiography and mean water depth of the correspond • ing basin. The Coriolis effect induces current direction change and in some shelf seas, the shoaling effect of the sea bed and basin configuration produces elliptical or rec • tilinear reversing currents (Johnson, 1978). Meteorological currents are quite important in shallow shelf seas in that they are the dominant source of • energy on open shelves. Meteorological forces are manifested by the transfer of energy through fluctuations in barametric pressure and direct wind stress. Four predominant • types of water movement result: wind driven currents, oscillatory and wave drift currents, storm-surge and near- shore wave-induced longshore and rip currents (Johnson). • Sediment transport in the benthic shelf environment is in fluenced by the interaction of waves and unidirectional • • t/I • • 2 The temperature of the adjoining coastal region, together • with rainfall, strongly affect the type of sediment and the sediment distribution on the inner continental shelves • (Fig. 2). Salinity of the seawater in the benthic boundary layer is fairly constant at approximately 33 ppm. Description • In fully describing the benthic continental shelf ecosystem the physical, chemical, biological and geological processes are relevant . • ~hysical Processes Currents and waves are the physical processes that modify the benthic shelf regime. These are generated by • local winds and waves, tidal forces, and other global atmos pheric circulation systems controlled by solar radiation. Four main types of shelf currents are generated by these • forces: oceanic circulation, tidal currents, meteorological currents and density currents. High and low latitudes set up a differential temp • erature balance which results in oceanic circulation patterns. Although the major currents exist on the oceanward side of the shelf edge, they encourage an active interchange between • shelf and oceanic waters. This interchange takes the form of large eddies spinning off the main oceanic current on to the shelf or results from lateral migration accompanying • • 93 currents. The waves cause sediment suspension while the • 4 directional currents serve as transporting mechanisms. Density currents are generated by variations in • temperature, salinity, and concentration of suspended sediment. Density stratification occurs at the mouths of rivers where suspended sediment is carried offshore by • denser salt water. The effect of freshwater floating on this process on the benthic shelf zone is that the seaward flow of lighter surface water induces a shoreward flow of • bottom waters. Chemical Processes It is in the sediments that enhanced chemical and • • biochemical reactions take place due to the bringing together of minerals, organic matter, and sea water, which are not at chemical equilibrium. Sediment-bottom water exchange is a major process for controlling the chemical composition of the oceans. (Fig. 3). This exchange is often initiated by flow of water • • due to compaction, and flow of water plus enclosing solids away from the sediment water interface due to depositional burial. Distribution of chemicals in the watery portion of the sediment water interface is a function of the • • 91 • • • • • • • • 5 chemistry of the underlying sediments, factors which disturb sediment water interface, and the physics of transport within the bottom water. (McCave, 1974). In the sediments, diagenic chemical reactions, those occurring during and after burial, can be divided into biogenic and abiogenic categories. Biogenic reactions are those mediated by bacteria and other microorganisms. Abiogenic reactions are the inorganic reactions, those not mediated by bacteria or other microorganism. Biogenic reactions are dominated by geochemically important bacteria in sediments that require the preexistence of organic compounds for their metabolism. Therefore, these reactions are intimately tied to the deposition of organic matter and rates of deposition are important. High rates of deposition are favored by high planktonic productivity in the overlying water, and quick settling and burial to avoid decomposition in the water column. Some of the most important chemical reactions are the result of this microbiological decomposition of organic matter. They include: removal of dissolved oxygen, pro duction of carbon dioxide, reduction of nitrate, reduction of sulfate, and production of ammonia, phosphate, hydrogen sulfide, and methane. For specific chemical reactions (S e e Table 1). • Products of bacterial reactions can, in turn, react to cause further changes in sediment chemistry. An excess of bicarbonate ions produced by sulfate reduction • 6 • and ammonia formation leading to the precipitation of calcium carbonate, would be just one example. Abiogenic reactions are less important. They • include: dissolution of opaline silica, dissolution of calcium carbonate at sediment water interface, recrystallization of carbonate minerals, cation exchange between • pore waters and clay minerals, formation of authigenic clay minerals, dissolution of feldspars, and reaction of volcanic glass and basaltic minerals with pore waters to produce new • silicate phases. (McCave, 1974). Geological Processes The geology of siliclastic benthic continental • shelves consists of five interdependent factors. They in-elude rate and type of sediment supply, type and intensity of the shelf hydraulic regime, sea level fluctuations, cli • • mate, and chemical factors. (Reading, 1980). Only chemical and hydraulic factors have been discuss ed. Direct sediment supply is negligible, except at the mouths of the world's 12 largest rivers. Sediment which bypasses river mouths is overwhelmingly fine grained suspended sediment, main ly mud. Mud blanke t s frequently extend • across the full width of the shelves. (Holeman, 1968) . • 7 Modern shelf sands are mainly relict. However, external sand supplies to the shelves occasionally come from river mouths during floods and from beaches during storms. Long term sand supply is most likely from deltas that are tide dominated, and where conditions near equilibrium enable interchange of water and sediment between inshore and shelf environments. (Reading, 1980). The natural processes of deposition, transportation, and erosion are shown diagrammatically in Fig. 4. Climate is important because it affects the type and rate of erosion and weathering on the continents, thus determining the type of sediment available to the ocean. (Reading). Continental shelves are considered to be an extension of the continent and were produced during the last Ice Age when sea level was lower. As the glaciers melted, approximately 15,000 years ago, the coasts were submerged by the rising seas and conse quently produced the continental shelf. Although this may be a reasonable origin, continental shelves may also be modified by deltaic sediment accumulation, coastal uplift and subsidence or large scale lithospheric plate motions. (Dietz, 1952). • • • • • • • • • • • Benthic Fauna and Flora The sublittoral zone, which extends from low tide levels down to the edge of the continental shelf, is well • 8 • nourished by nutrient-laden rivers and upwellings of d8eper nutrient rich waters from below. In addition, a rain of detritus from pelagic organisms nourishes this benthic com • munity. 1 Thus, a diverse and rich collection of benthic fauna and flora abounds. Before discussion on the specific phylums of the benthic continental shelf ecosystem, one • very important physical condition should be stressed. The photic zone of the oceans extends to a depth of 650 feet below the surface . Thus, an entire shelf sea can lie within • • the photic zone. (Laurie, 1972). In addition, more than half of the shelf lies in the upper portion of the photic zone, the euphotic zone . All primary production by plants takes place in this region. The benthic organisms live in or very close to this highly productive zone. This essen • tial factor, combined with detritus and terrestrial input, • is why the benthic shelf ecosystem contains such an abundance and diversity of organisms. Flora, in the benthic shelf ecosystem is mainly confined to four phyla of algae. (Table 2). The blue-green algae have a high tolerance to salinity, light and • • 98 • 9 • temperature fluctuations. They are minute one-celled plants that lack a distinct cell nucleus and are colored blue-green due to the presence of the pigment phycocyanin. Marine forms of the green seaweeds are rare, however, those • forms that are present in the benthic shelf region are multinucleate, calcareous and contribute to bottom sediment. The brown seaweeds, of the phylum Phaeophyta, are attached to • the hard substrates of the continental shelf and have hollow floatation bladders enabling them to float if their attachment is lost. The calcareous red algae are found worldwide • in almost every shelf environment and tend to live attached to the substrate. The presence of these forms in depths up to 200 meters is due to t heir ability to photosynthesize in • the blue and violet end of the spectrum. Angiosperms are not as abundant as the algae in the benthic shelf environment, however, Zostrea (eel grass) and Thalassia (turtle • grass) are two representative genera. According to Davis (1972), true benthonic fauna are restricted to the invertabrates. This statement does • not account for the animals who interact with the benthic shelf ecosystem due to migration, feeding, or mating processes. Table 3 summarizes the common marine benthonic • groups. The phylum Protozoa is best represented in the • • / • • • • • • • • • • • 99 10 benthic shelf ecosystem by the Foraminifers. Forams are characterized by their external, calcareous chambered shell and occur in a variety of shapes. (Fig. 5). These organisms are restricted in their distribution, for they are highly sensitive to changes in environment. The sponges of the phylum Porifera are multicellular, sessile organisms that require a firm bottom on which to live. Organic debris is circulated through the sponge by means of ciliated cells, creating a dependence on water circulation for nourishment . The sponge is made up of siliceous or calcareous spicules (Fig. 6), which are disarticulated internal skeletal material. (Davis, 1972). Coelenterates of the benthic community include the classes of Hydrozoa (Fig. 7) and Anthozoa, and both grow attached to rocky substrates. Benthic marine Annelids (Fig. 8) may be either sessile or free moving and feed in a variety of ways. Some have a specially adapted proboscis to prey on small organisms, while others filter feed or detritus feed. Gastropods and pelecypods (Fig. 9, 10) of the phylum Mollusca tend to travel on or burrow into the sediment of the benthic shelf. The gastropods are herb ivores or carnivores and feed on the soft tissues of other animals by penetrating their shells with a characteristic radula. Pelecypods tend to burrow into the shelf sediment and feed through long inhalent and exhalent siphons. ~ig. 11) . /IJO • 11 •Arthropods of the benthic shelf are represented by the subclasses C:irripedia (barnacles) and Malacostraca (lobsters and crabs). Barnacles (Fig. 12) tend to live attache d and extract food from water by means of cirri, while lobsters • and crabs (Fig. 13) crawl along the shelf floor and gather food as omnivores and scavengers. Echinoderms of the benthic ecosystem (Fig. 14) are mostly free-roaming on the sea • bed, yet are found to float or live attached. Feeding habits will vary with each class; some feed on bottom detritus or small animals while o t hers are browsers or filter • feeders. Marine fishes that concern the benthic shelf ecosystem are those that directly impact with the sediment • for protection or feed on the abundant fauna. Fishes that habitually rest on the bottom are termed demersal. Demers al fishes can therefore be thought of as benthos, although they · • can swim. Some common demersal fishes of the co ntinental shelves are the flatfishes. Ot her fishes existing near the benthic shelf environment include: Anglerfishes, Perchlike • fishes, Codfishes to name a few. The fishes will descend to the shelf floor to obtain food from this highly productive environment. • Obviously, the benthic continental shelf ecosystem contai ns a consider able variety of marine benthos. • • • /tJI • 12 Unconsolidated sediment anq hard outcrops are dominated by epifaunal organisms that are both vagrant and sessile. Areas with sand and mud bottoms are populated by infaunal • • organisms. Filter feeders are infaunal, while grazers and scavengers tend to be epifaunal. Thus, most morphological and physiological adaptations of the benthic organisms are closely related to the bottom sediment composition~(Fig. 15, 16). • Benthic Energy Flows and Productivity In the last section, the various phylums of the benthic fauna and flora of the continental shelves were discussed. How these organisms fit into the various benthic • • communities is significant to the energy relationships within this overall ecosystem. In Figure 17, these energy relationships are diagrammatically represented. • Food, the key to the success of any ecosystem, comes to the benthic animals in the form of living organic matter, microorganisms and heterotrophic bacteria, dissolved • organic matter and detritus. Abundant algae in the shallow shelf regions of the middle latitudes are a primary food source for the benthic omnivore~ while at the same time pro • vides organic debris for the sediments. This living organic matter extends to approximately 60 meters and is common on rocky continental shelf bottoms where the plants can attach • /02.. • 13 •themselves. Diatoms and other unicellular algae make up a thin microfloral film on shallow water sediment which is an additional food source for the benthic organisms. Bacteria tends to concentrate in the surface layer of the • sediment as do chemosynthetic species that metabolize inorganic compounds. (Tait, 1975). Another important food source for the benthic continental shelf ecosystem is par~ • ticulate matter sinking from the populations above. The energy sources in detrital form are summarized in Table 4, and include contributions from primary, secondary and ter • tiary production from the pelagic ecosystem. One of the ways that land impacts the benthic shelf ecosystem is through the addition of organic matter in the form of wood • or leaves. Thus, pelagic detritus, primary producers, chemosynthetic autotrophs, bacteria and dissolved organic matter all provide food for the benthic continental shelf • ecosystem. Benthic organisms obtain the previously discussed • energy in the four basic ways: filtering of suspended particles, collecting particles that settle on the sediment surface, feeding from sediment incorporated organisms, prey • ing on other animals, or combining these methods. The biomass (weight of living material per unit area) of any ecosystem is dependent on the availability of food and the • • • /(J3 • 14 ability of the organisms to obtain nutrients. Consequent1 y .~ the biomass of the benthic continental shelves can be as • high as 100-150 g/m2 (Tait, 1975) . This value corr~sponds to the high productivity characteristic of continental shelves .• The food relationships of the benthic continental shelves are further understood by considering Figure 18. Although the diagram appears complex, the basic dependence • of the benthic organisms on sinking detritus and on one another is evident. Within the benthic shelf food web, a variety of carnivores prey upon the suspension, sediment and surface • deposit feeding organisms. These carnivores include many of the food fish utilized by man. This simple extrapolation from the benthic food web illustrates one way in which the • continental shelf bottom community interacts with other ecosystems. Further relationships between man and the benthic continental shelf, as well as continental shelf resources• provides an interesting insight on the significance of the benthic continental shelf ecosystem. Benthic Continental Shelf Resources• The benthic continental shelf ecosystem provides • a variety of mineral resources. (Fig. 19). These resources include: oil, gas, sulfur, heavy minerals, sand, gravel, • • 15 phosphorous, shells, and fresh water. (Boyer, 1974). Most • valuable of these resources are the mass accumulations of oil and ga's. At present, one third of the world's pr o duction of oil and gas is from this offshore source. Sulphur also • occurs within the continental shelf, in rock layers overlying salt domes. • • • • • • • • •Coat I\ l•on $ ''" ,, s..h M.1••u•n•••• Ncwtu••• . F,!J . t'f Left: this m:ip shows how mint·rali; an• distrihut1•I to lw solvt•d. • • 16 Heavy minerals are concentrated in placer deposits. These are deposits carried from land onto the shelves by • rivers and concentrated by the winnowing effects of tides and waves at the beach environment. The later rise in sea level locates these concentrations on the continental shelves. • Of these placer deposits, tin is the most valuable, while gold, platinum, titanium, ilmenite, and rutile are of lesser interest. Dredging the floors of continental shelves yields • sand, gravel, and shell along with zircon and monzonite sands. Phosphorite nodules and sands from the benthic shelf ecosystem are becoming a valuable source of fertilizer • phosphate. One resource that is not always considered is the fresh water found in aquifers that extend seaward beneath the coasts . (Boyer, 1974). Presently being utilized, • these aquifers are providing to be a valuable resource of the benthic continental shelf environment. The fisheries of pelagic fishes are important • because they reflect the high productivity on continental shelves. Man's Impact • Increasing population on the world's land masses naturally increases the amount of wastes to be disposed of. Much of this waste reaches the ocean shelves either directly • or indirectly. • /o(p • 17 • DDT and its residues are found in the ocean waters in concentrations of parts per trillion, yet in the fish, levels of parts per million or tens of parts per mil~ion are • not uncommon. These concentrations in edible fish affect man directly. Oil and DDT have been found to be transferred • from prey to predator. In tracing pollutants through foods, biologists have shown that effects of biocides are lim not ited to target species. They travel through food webs, • disrupt reproduction, and inhibit photosynthesis of algae. The major amount of oil pollution comes from washing cargo tanks at sea. Other sources of oil pollution • ar_e: losses from collisions during loading and unloading, accidents on high seas or near shore, losses during exploration and production, and losses in pipeline breaks. • Oil and oil fractions are extremely detrimental to continental shelf communities. Many organisms die of coating and asphyxiation or direct poisoning. Oil also • kills organisms in their juvenile forms that would not be killed as adults. It also weakens many organisms making them susceptible to infection. In addition, pesticides • have high solubilities in oils, and low solubilities in water, therefore oil slicks in coastal waters can concentrate pesticides. • • • /b7 • 18 Man's sewage consists of nitrogen, potassium, and phosphorous, the primary nutrients for plants and algae; If a significant quantity of sewage is deposited in~o a • basin, the result is a proliferation of photosynthetic growth. (Munday, 1976). Eventually the oxygen demands of wastes and decaying photosynthetic tissue all but eliminate • • higher animal life. This process is called eutrophication. It occurs naturally but is accelerated unnaturally by large sewage inputs . (Munday, 1976). This analysis of a smaller b~sin can give us clues to what will happen on continental • shelves if sewage disposal becomes exceptionally large. Conclusion • By examining the various components and processes that characterize the benthic continental shelf community, some broad conclusions come to mind. This benthic ecosystem • is highly productive, therefore it represents one of the most vital links to the marine food web. Continental shelves are found throughout the world and at every latitude, over • lapping into practically every existing ecosystem. An essential basis for the understanding of the mechanisms of a complete system is proper understanding of the dynamics of the • benthic regime. Moreover, a sound understanding of the benthic continental shelf ecosystem will enable man to properly manage the abundant natural resources of the world's oceans . • • 19 • REFERENCES Boyer, Robert E. (1974) Oceanography, 48 p. Hubbard Press, Illinois. Boesch, Donald F. and Hershner, Carl H. (1974) The Ecological Effects of Oil Pollution in the Marine Env~ronment. In Oil Spills and the Marine Environment, 114 p. • Ballinger Publishing Company, Mass. Davis, Richard A. Jr. (1972) Principles of Oceanography, 434 p. Addison-Wesley Publishing Company, Mass. Dietz, Robert S. (1952) Geomorphic Evolution of Continental • Terrace. Bull. of the Amer. Assoc. Petroleum Geologists. Vol. 36, No. 9, pp. 1802-1819. Hedberg, Hollis D. (1970) Continental Margins from the Viewpoint of the Petroleum Geologist. Bull. of the Amer. Assoc. Petroleum Geologists. Vol. 54, No. 1, • pp. 3-43. Holeman, J.N. (1968) The sediment yield of major rivers of the world. Water Resources Res., 4, pp. 737-747. Johnson, H.D. (1978) Shallow Sileclastic Seas, pp. 207-258. • In Sedimentary Environments and Facies. Blackwell Scientific Publishers, England. Laurie, R.H. (1972) The Living Oceans, 350 p. London Press, London. • McCave, I.N. (1976) The Bentic Boundary Layer, 323 p.Plenum Press, New York. Munday, John C. (1976) Priority Problems and Data Needs in Coastal Zone Oceanography, 107 p. Virginia Institute of Marine Science, Virginia. • Reading, H.G. (1978) Sedimentary Environments and Facies, 557 p. Blackwell Scientific Publishers, England. Tait, R.V. and Desanto, R.S. (1975) Elements of Marine Ecology, 327 p. Springer-Verlag New York Inc., • New York. Webb, J.E. et al. (1976) Organism ·sediment relationships. In: The Bentic Boundary Layer (Ed. by I.N.McCave), pp. 273-295. Plenum Press, New York. • • • LANO SHELF-SEA __ CONTINENTAL --DEEP OCEAN MARGIN . :: .g ____ --SEA LEVEL-.---. 0 -2 IOOK"' ~K'" o • f lhc •·ontincnlal nrnrgin. ( t&t);t;.t..\. ffcdb.,..J l'fJo) lvt:~Tic•• £..GGCHTI"" '°" . • Fii:urc I G•·o11111rphrc feature~ o 4--Rainfall (PPMd; in.) 100 0 O",--· 1· I I Areas of maximum conce11trat1011 of • , gravel. sand. I and mud • 100 . 'Rccnlrallon of gravel, sand and .mud on Hi:. ~ \rc:as of ma'1mu~ ~I • I 10 tcmrcraturc ilnd ramran of the tnllt' r conlmcntal shcl('"m~c~~, J'f'I') .idJ" lfl"l!-' ,·0,1,tal rc1mms, o.f, • T ble J Some Representative ~eraU ~iogenic a Chemical Reactions in Sedunents NH; HP04- . . . . CO production Oxygen uhhzation, 2 C02 Hco; CH20 + 02. -C02 + H20 02 No; so;CH4 HzS Nitrate reduction . · '' 4HCO -+ C02 + 3H20 SCH20 + 4N03--:-+ 2N2 + 3 ++ ++ ++ K + MQ++ CI -Co . Fe Mn Sulfate reduction2 -H S + 2HC03 • 2CH20 + so.. -2 No •c7> Ammonia'formation CH COOH + NH3 CH2NH2CO~H+ 2(H) -j Methane formation . 2H 0 O +8(H) -CH4 + 2 . purposes only. C 2 d e for j!Cneral illu~trahve aor11:anu.: compound~ rc~~~n~;og:~ furnisht.-d by or11:a11ic c~~~~••) (H) represents reproduce y <~ . • Fig~ by arrows) expected for· dissolved Direction of fluxes (shown d sediment pore waters. lf'1't)constituents between sea water an l""{PA-ms.~> Suspended ~onsport -susPE:N'Dm..... 7"" SEDIMENT Flocculation Aooreoallon :-1 ____ • L c 0 ~!l! a: Bed-load Transport ---.·-§-.a8. ·;; f"' ~ Currents Waves ~ 8. :; Bioturbation "'Q. ~ --~ Cl) cF 0 ... I- z "' :E c Cl) • "' _ { Consolidation ·~ Oio9enesi1 ~ Deformation .. ---------------~-,;~) • rig. ...... Benthic boundary sedimentary processes(-0 ,qi,,.. --: h /lo • C\'anophvta (bl 150 Microscopic Chlorophyt ( ue-green) 900 M1cr0Kopic to m . Phaeo h . a green) Microsco.pic t ass'.ve Rh d p )ta (brown) Microscop· o massive o ~ph)'ta (red> ic to massive • Protozoa Single-celled . Sponges animals Porifera Coelenieratll Corals and Annelidll Round wor:::semones Mollusca Pelecypodll Clams, oy.sters Ftureri• Snails • scallopsGastropoda fig. " Vari~us genera of gastropods (snails)Arthropod Barnacles 1 PeetenEchinod a (Crustacea) Sand doll' obsters, crabs T ermatll ars, sea ur · L . cmns, starfish ......:.::::.....:: ::. :.::~ .. ~~:::.~.~:.~ . . \ fl • 25~· • 25mm.1 I~· ·~ e-·,.\,\; /<~~ vJJ~ 'i._, . . . ·.'. \. . ;. Crusostr.. ~\.-.>:ri. .--.1 ·,~ ~ '-._.i__),/. · • ~g. JI!; Selected pelecypod (claml genera · Fig. '5 Various types of benthonic· Foraminift'ra. lnhal•nt siphon .~"'l---1 A~~mbla11eoftyp1cal. l.ulte shell Oflt;m1sms . . · ·i~~~ • .. Fig.''· siph Infauna! I ons extended. pe ecypod with • -~---· fl1. 6J Various sh• ---~-.. " .JM!S U\umcd by spon ' . . ge sp1cult.-s. All ~rc m1<:rO\COpic. • • • Fi". 7-T . term). (Aftl'/~IC~I hydro10Jns O p<-n S . 11.mfy 19S hN· "'· Houht ' . 9, The 11 on M 1fflrn, p. 96.I Fi~. 11-.. w-tl..nt,1ry t1 ~~ose-necked b.trnacles. a Fig. l'i 0 h. member of th~o~~nerPi~ annu/ara a iuro1ds or brit1ie s~~r~mon //( .. -----------·------------------------------ ···· -·····-·-·-~·-·- SEDIMENT OHIGIN :.11;1\ltN. rn·~-lr· ---~. ----~----------------0---·--------- Relict _ --· -.--~~ydrudynmc "~"'~'-~':~'~--_ _-·--··-··-_ ·---· -----j Physoc:lll Su!Atr.ite Cond1t1un• B1uge111r At:11v11y [__----------------· •• I·GRAVEL H11/1ly unst.ible . ' Alm. >;,ml wave• Iii sand ridges. Active developed m.crofau11• Nu ep1fau11.i. w.iter e•chan!J!! ·--------·---------------··----------1--------'------.,,.+-------------t f erm 'ubst. ale due to packmg ~---M ·r &toll.ii •chon. Sm•ll·sc;ile w.ive Iii c:um·n• Jtpples. Active sediment ''"''"'''" 1 011 , 1 sm•ll·sc..I~ Sm.ill mt11r •toto.11 vu1.J-. Fluctutttong "'"nsity uf tod~I Iii w•ve ...:11v11y 11.ior WCJlhe1 Iii •torm .-un 1h1111ml Alh:111.il•11y w11d dJy IJV"" .(\1111m \.in1l l.iy"1~I . lhgh 11ron1Jry 1110 I •IU<.hvoty & l ~•ye "'Y"'"" ntJ.ller nmtm1t, "'" IJttr.1 1leucJ•11111 wilh dt' Jl!h W.ilr.r con11:11t h1!j11 Hoyh SUSfMtlltJortl •• + MUlJ M.•1ltmr11t cunt.:ttutr4t1CH1~ &/m tow w•w , .u,~, "'":•m•., Poor mterst1t1;it f;iu1w . D1ff1cull to 1..rrow. but suot•blr org.111S1ns m.iy be common. Su>1>er,.1011 fcc911'11t. Activity Stable pore spllCM lolled with sm4ller Well ·developed epifaurw Iii mterno1t1I giams. 1nfaun1. ·--·---------------·------------- low diverStty of me1of1un1. Well · Immobile subUr•t•. "1~·sedimentation. developed m.croh1una. SuspenMon feeders Iii deposit feeders common. , Soft Iii loosely itklcwd. Re;idily· trans· lntenhli•I f;iun1 poorly understood l_l<>'ll!d sediment. Suspension fe..ders domm.ile. .' .. Probably ;ill feeding types prewnt. Not ;itfected bV t1d;il currents. Homo· Reduced or~noc nw1ter reduce\ P<>PU· gemsed s4nd cldy sedunvnt forming 60% li1t1011 s11e•. Specie> d1vers11y hovh due to of •hell >ed1rnc11ts. ~ewer e11voro111nc11t.il l.ick of dom111.i111:e Iii yre..tcr prrdoct.i ll11i:t11.it11111• & lowe1 promJIY 11roouchun l11h1y of •~•v11011me111. Highly biotur 1ho1n 111 Hece11t ,,..,d cldy IMted govong onc1e.i~d >trurtur;il com· 51l~x11y ut t!nvuunnwnt . . j.:~..:~y~~'Sf~:,.,:, -f~der> No 111te1 H•rd su!Atr•I•. 11oc:lud111y pe•tllr former '"11"' '"'""'·mu 111 & llll'•ul••in.i 111 lo1vrmno1l/ Llll<'n liu11uw1t11j ~JtcC.:tt:\ \V1th mt111y Jte•miMumt hurruW\ -------------·----·--------- H' I .... • .. ·--+ SohcJ tran!;port Redox potential discontinuity (RPO) • Fluid transport Oxidizing sediments above RPO Fia; lb. Some methods of orvanio;m modifkation nf t...c henthic boundary layer. /\. Surface dweller (fish) dislurhinl! surl:tl''C scd1mcn1.; R. Fpil'aunal susrcnsinn feeder rnnwrtinl! susrcnded sohds into dcpo.,it far.,:cs; C tpifaum1I ,fe(l'l"ll fcetlcr I~mstrnpo.l' disturbing the surface, forming ll n1t1\.'.,S lrJ:I and m"·;·c;1..-in!! rart1~·lc si1c h\ faecal • deposition: I>. InfaunaI suspension feeder (polv~:hacte) circul.uing the in1crs111ial wall'r; E. Infauna! dcpo~il fl·cdl'r ((1'1l\,·l1ac1c; tran"f"•lrtintr sc•22 Skcol/m~yr lots to ud1fftcnt f"i ,(llrt /"f" llin(rmnmnlit rtf,,nr11/nlim1 11!' h1·f>"//,,1iwl r11.-ri:r r1/ntinn1hips in n 1nnrinr. ,,,;11•1/m1111 ,,.,,,,11/ ...,,,,.,., o/ ti" .\. ,1t/1 . t: /,;•1lit . l-1 ::10,' . ,, 111,· .,,,,,,,., lutrr 11111'/.J '.'I ~((t//m:/,r kcal/m1/yr Ero11~. drain.&•• .and sinking, uneaten phytoplankton 70 org..l'.'JC matrr1..l• From primary production {phytoplankton eaten but egested 28 '''!"" w.ci dead, uneaten zooplankton . 5·6 From secondary production {zooplankton eaten but egested 5 From tertiary production : dead pelagic predators Total = 109·6 .', . '/, FitMrt r8 Sor111 AN FACrof\S • __/ I ---/ • CHEmICAL FACTO~ A8106en1c.. t ~--......c:.___ D1!5SoL-uTIC>N • '-------I OF me~· ,. • BL/: • EUCABETH 6oOOm'\~ il~A RtcttdrO..S 6. The Ecosystem of the Deep Ocean • Mark P. Hemingway Mary E. Lyons • I. Introduction I I. Scope (areal and geological) A. Area: Below 2000m depth, 303 x 106 km2 B. Geology 1. Includes abyssal plain, continental rise and • lower slope, rudges and trepches 2. Substrates a. bare rock b. fine sediments or oozes I I I. Physical Parameters • A. T -Below 2000m T 2°C, annual variation of ± 0.2°C/yr. B. P=--10rn/l bar C. Light-Intensity 10-lO surface levels below lOOOm depth D. Water clarity -higher than surface, up to 95% • E. ~urrents - • composed of small particles which sink at various rates from the upper productive levels of the ocean. Most of this matter consists of dead cells, especially phytoplankton, which have • very low sinking rates (on the order of 1 m/day). These low sinking rates preclude single cells from being a significant pathway for organic carbon to t he bottom since mineralization • and dissolution would effectively remove all nutrients before substantial penetration of the water column (Kinne, 1978). It has been determined, however, that the action of copepod • fecal pellets, both in their aggregation of these cells and in their protection by the peritrophic membrane, permits particulate matter to reach the lower levels of the ocean • (Carey, 19 31; Hinga, 1979; Kinne, 1978; Macdonald, 1975; M2guire, 1981). Table 1 illustrates relative sinki~g rates. Copepod fecal pellets are extremely important because of the • high abundance of copepods in the ocean's upper dimension (Honjo and Roman, 1978). Other particles which contribute to the rain of organics to the bottom are "reproductive products, • dead bodies, and exoskeletons of the zooplankton" (Kinne, 1978). The second settling mechanism, which may be termed wind• fall settling, involves macro-and me gascopic particles which consist of large dead fauna with correspondingly high sinking rates. The nature of this organic matter dictates a sporadic • settling pattern, often with large distances and periods of time between particles reaching the bottom (Haedrich and Rowe, t 1977). There appears to be a rough inverse relationship be tween the surface productivity of an area and t he ntmber of parti cl es reaching the bottom below it. This may be explaine~ by the higher macrofaunal mortality in the oceanic "deserts" -b • l~/ of low pro:~ctivity (Isaacs and Schwartzlose, 1975). Examples of windfall part~cles include "fishes, whales, squids, and decapods" (Haedrich and Rowe, 1977). • The relative importance of these different mechanisms • is not well understood. Different sources stress one mechanism strongly over another. For example, Menzies, et al. (1973) places greater importance on horizontal transport than on • vertical settling, while Macdonald (1975) takes the opposite view. Until more information on the deep ocean is available, the controversy will, no doubt, continue . • ORGANISMS OF THE DEEP SEA Microorganisms There is relatively little information on deep sea mi • crobes, primarily because of difficulties of sampling tech niques. As a general trend, microbial biomass in the water column decreas0s strongly as a function of depth (fig. 9) . In the benthos, populations are dominated by heterotrophic aerobic bacteria (e.g. Bacillus sp.). Also found, but in lower • abundance, are other bacterial types (e.g. anaerobes, sul fur-reducers, etc.), diatoms, some rare foraminifera, and fungal spores. These microorganisms tend to be barophilic • (i.e. functioning more rapidly and efficiently at high pressures) • and tend to be concentrated (up to 99%) in the upper 5 cm of the sediment. The pelagic realm is dominated by predatory copepods (e.g. Spinocalanidae sp.) (Macdonald, 1975) . Macrofauna Macrofauna of the deep sea may be divided into two general • groups, based on their lifestyle. The first subsists, by de trital or suspension feeding, on the relative concentration of fine organics at or near the sediment-water interface. The • second group consists of pelagic and bento-pelagic carnivores -7and scavengers that exist on other organisms and the large /~ • windfalls which descend from overlying waters. Obviously, these two groups depend on different nutrient transport mecha nisms for their food supply. A sample faunal list for these • groups is given in Table 2. The detrital/suspension feeders depend mainly on the rain ol fine organic particles and their resulting accumulation • on the sea floor (Menzies, et al., 1973). This group includes most deep sea invertebrates, with the most commonly found members being polychaetes, ophiuroids, bivalves, and crusta • ceans (Macdonald). Studies by Sanders and Hessler (1969) indicate that the relative diversities of these groups follow the trend 1 species ophiuroid: 4.1 species bivalve: 9.7 species • polychaete: 16.5 species crustacean if 1000 individuals are counted for each group. The type of feeding behavior shown stron3l~ depends upon sediment type, with suspension feeders • dominant in areas of low clay content, and detritus feeders prevalent in areas of high clay content (Menzies, et al., 1973). In contrastr the other group depends upon predation and • scavenging for food s,upply. Because the benthic macrofauna is insufficient to support these organisms, predation is probably secondary in importance to scavenging (Haedrich and Rowe, • 1977). The most important members of this group are the macrourid fish (grenadiers and rattails), sharks, hagfish, and cephalopods. • The nature of the windfall occurrence on the bottom dictates the behavior of these organisms. Due to the intermittent and variable character of windfalls, organisms that de • pend upon them for survival te~d to be widely-ranging generalized feeders (Isaacs and Schwnrtzlose, 1975; Pearcy and Am • • -obler, 1974). This is important because of the necessity of 1~3 searching over a large amount of area for isolated occurrences • of food of a highly variable composition (Haedrich and Rowe, 1977). These animals may rely on olfaction for detection of windfalls. However, due to the distances involved, this alone would probably be insufficient. It is likely that organisms • are more dependent upon detection of the "successive collapse • of loosely established territories as the scavengers that held them move closer to the (windfall), each invading the territory once held by an absent neighbor" (Isaacs and Schwartzlose, • 1975). Metabolic demands per unit weight are greater for small organisms than for large organisms. Therefore, one would ex pect an increase in size to correlate with increasing depth. This would be due to the decreasing abundance of windfalls • penetrating successively greater distances through the water • column. Preliminary findings indicate this to be the case (Haedrich and Rowe, 1977). Deep sea photographic studies show a general pattern of • scavenger appearance at a bait can (an "artificial" windfall). The number of pelagic scavengers, especially macrourids and hagfis~' r at the bait increases slowly with time, peaking after a few hours. Activity levels are high with frenzied feeding displayed by the fish and also by invertebrates (e.g. ophiu • roids, amphipods, echinoids) which are attracted by the bait . • Usually, tests ended after three to eight hours with the appearance of a . large organism, typically a shark of five to eight meters long. These move in and drive off the other sca vengers, eating most of the bait. This leaves only scraps to be devoured by crabs, echinoids, gastropods, etc. (Isaacs and • Schwartzlose, 1977) . -9BIOMASS • Biomass of the deep sea is low relative to that of the upper layers (Menzies, et al., 1973). The preponderance of data indicates that biomass decreases strongly with: 1. dis • stance from land and 2. water depth (fig.5, fig. 10) (Carey, 1981; Macdonald, 1975; Menzies, et al., 1973; Rex, 1976; Rowe, 1971). This trend may be explained by the previously • discussed mechanisms for nutrient transport, specifically horizontal transport via turbidity currents off the continental shelves and vertical settling of organics through the • water column. The biomass of detritus/suspension feeders also seems to be directly related to the primary productivity at the surface (Macdonald, 1975; Rowe, 1971). Scavenger/ • predator biomass may show the opposite trend due to the lower abuncance of windfalls under highly productive areas (discussed under organic transport). • As a result of these trends, biomass values for the deep sea vary widely. For example, trench biomass tends to be relatively high due to their proximity to terrestrial sources • of organics and their tendency to trap sediments containing organic material (Macdonald, 1975). Values range from 0.68 to 1.0 g/mL in the Kurile-Kamchatka Trench down to 0.076 to • 0. 04J g/m:i in the Sunda Trench (Menzies, et al. , 1973) . This is in contrast to typical biomass of the red clay region, which has values only up to 0.05 g/m'Z. (Macdonald, 1975; Men • zies, et al., 1973). These values correlate well with the amount of organic material available form primary sources. ADAPTATIONS • Bioluminescence The biological emission of light is very common and has a variety of functions. It may involve up to 99% of the indi • -l.v • victual organisms of the deep sea (Macdonald, 1975), most of • which utilize the same basic mechanism. A symbiotic bacterium, such as Achromobacter fisheri, oxidizes an aldehyde to produce luminescent flavin mononucleotide. This then is regenerated by • DPN oxidase (fig. 11). Bioluminescence may be used for several purposes. These include protection, such as the use of a "flash" of light to • blind or confuse a potential predator (Macdonald, 1975). Another mechanism which is important is communication and location. This plays an important role in breeding (Menzies, et • al., 1973), and in shoaling and schooling of deep sea fish (Macdonald, 1975). A third function is the use of bioltm1inescence as a lure for prey, such as by the deep sea angler • fish (Macdonald, 1975; Menzies, et al., 1973). Ph~sio-behavioral Adaptations The physical and behavioral adaptations of deep sea or • ganisms are myriad. A few of the most important or prevalent examples will be mentioned here. Many groups exhibit unusual breeding behavior or habits . • Sexual dimorphism is common. Probably the most extreme example is found in the deep sea angler fish. These have dramatic size reduction in the males, which often exist parasitically atta '• ched to the body of the female (fig. 12). This reduces both the strain on the next lower trophic level and the difficulty of mate location in conditions of total darkness (Macdonald, 1975). • Also, most organisms deliver young at a more advanced stage than near-surface organisms, thereby reducing mortality rates in this harsh environment (Menzies, et al., 1973) . Patterns in nutrient uptake may also be different from surface styles. One example is that of a deep sea gastropod • which reingests its own fe ces a few days after excretion. The -11 feces by this time are enriched in nitrate from bacterial • action, thus providing the gastropod with a needed source for a scarce nutrient (Raymont, 1971). Another example is the expansion of gut length in some deep sea bivalves (e.g. Abra • profundorum) in order to achieve maximum extraction of nutrients from food (Crisp, 1975). The angler fish have evolved a host of luring and capturing structures from their body tissues • (Macdonald, 1975). Visual structures (i.e. eyes and pigment) have undergone different adaptations for different groups. In most inverte • brates of the deep sea, both pigments and eyes tend to be reduced or absent (Macdonald, 1975; Menzies, et al., 1973). On the other hand, various deep sea fish have undergone extreme • expansion of ocular capacity. Through the development of large, highly-transparent lenses, abundant long and narrow rods, and often a reflective tapetum, these fish have increases • their light-sensing ability to fifteen to thirty times that of human capacity (Macdonald, 1975). MAN'S IMPACT • Man's impact upon the deep sea realm has been limited, primarily because of its inaccessibility and sheltered position. However, potential for stronger impact does exist. • Dumping of undesired materials is one well known mode of impact. The deep sea has always appeared attractive as a disposal mechanism because of its lack of visibility, distance • from human activity, and low biological activity. Intentional du.mp.ir\c~ , such as for dangerous substances (i.e. nuclear wastes and nerve gas), probably has the greatest potential for impact. • Unintentional dumping, however , may also be significant. Grassle (1975) reported beer cans, a 55 gallon drum, and a drinking fountain dredged from 1800m depth along the Gay Head • • -12Bermuda transect . 1~7 • One extremely important use of the deep sea which has been little utilized to date is as a source of metallic ores. These may occur as metallic sediments, such as those found in the -Red Sea Deeps (Bischoff, 1969; Walthier and Schatz, 1969), or as manganese nodules (Frank, 1976). These mining projects may • one day be econo~ically, politically, and technologically feasible, but at present are impracticable. Recovery of these commodities may carry a useful side effect. It has been sug• gested that the l ar ge quantity of water brought up from the deep ocean be used to produce a type of artificial upwelling. Due to its low temperature, this water may also 1 be used to aid in condensation at desalination plants (Roels, e t al., 1971). CONCLUSION• In the deep sea, a range of environmental conditions prevail which is found nowhere else in the world (Table J). It is not surprising, therefore, that organisms in this eco• system have evolved lifestyles and adaptations unique to this environment. Much research has been done, but the deep sea remains in many ways a mystery. More work will be necessary • to more clearly percei~e quantitative parameters limiting the deep sea environment. • BIBLIOGRAPHY Bischoff, James L., 1969, Red Sea geothermal brine deposits- Their mineralogy, chemistry, and genesis, in Hot Brines ~nd Recent Heavy Metal Deposits in the Red Sea, Springer • Verlag, Inc., New York, pp. 368-406 . Bruun, Anton, 1956, The abyssal fauna--Its ecology, distribution and origin: Nature, v.177, pp.1105-1108 . • Carey, A.G., Jr., 1981, A comparison of benthic infaunal abun--13 /.J-.f • dance on two abyssal plains in the NE Pacific Ocean: Deep Sea Research, v.28, no.SA, pp.467-480. Conan, G., et al., 1981, A photographic survey of a population of the stalked crinoid Diplocrinus (Annacrinus) Wyv'i llethomsoni from the bathyal slope of the Bay of Biscay: Deep Sea Research, v.28, no.SA, pp.441-4S4. • Crisp, D.J., 197S, Secondary production in the sea, in Pro duction of the World Ecosystems, National Academy of Sciences, Washington, D.C. Frank, D.J., December, 1976, Ferro-manganese deposits of the • Hawaiian Archipelago: Hawaii Institute of Geophysics, Publication. Grassle, J.F., 197S, Pattern and zonation--A study of t hebathyal megafauna using the research submersible Alvin:Deep Sea Research, v.22, no.7, pp.4S7-482. • Gross, M. Grant, 1977, Oceanography--A View of the Earth, Prentice-Hall, Inc., Englewood Cliffs, New Jersey. Haedrich, R.L., and Rowe, G.T., 1977, Megafaunal biomass irt the deep sea: Nature, v.269, pp.141-142. • Hersey, T.B., 1967, Deep Sea Photography, John Hopkins Press, Baltimore. Hessler, Robert R., et al., 1978, Scavenging amphipods from the floor of the Philippine Trench: Deep Sea Research, v.25, •no.11, pp.1029-1048. Hinga, Kenneth R., 1979, The supply and use of organic material at the deep sea floor: Journal of Marine Research, v.37, pp.S57-579. • Honjo, Susmu, and Roman, Michael R., 1978, Marine copepod fecal pellets--Production, preservation, and sedimen tation: Journal of Marine Research, v.36, pp.4S-57. Isaacs, J.D., and Schwartzlose, R.A., 197S, Active animalsof the deep sea floor: Scientific American, v.233-234, • pp.8S-102. Kinne, Otto, 1978, Marine Ecology,_Volume±, John Wiley and Sons, Inc. New York. Macdonald, A.G., 1975, Physiological Aspects of Deep Sea Bio• ~' Cambridge University Press, Cambridge. Maguire, Basset, 1981, Personal communication. Menzies, Robert J., et al., 1973, Abyssal Environment and Ecology of the World Oceans, John Wiley and Sons, Inc., •New York. • -14 • Pearcy, William G., 1976, Pelagic capture of abyssobenthic 1~1 macrourid fish: Deep Sea Research, v.2J, no.11, pp.1065 1066. • Pearcy, William G., and Ambler, Julie, 1974, Food habits of deep sea macrourid fishes off the Oregon coast: Deep Sea Research, v.21, no.9, pp.745-759 . Postma, H., 1971, Distribution of nutrients in the sea, and the oceanic nutrient cycle, in Fertilit;y: of' the Sea, V. 2,Costlow, F., Ed., John Hopkins Press, Baltimore. • Raymont, J.E.G., 1971, Alternate sources of food in the sea, in Fertility of the Sea, V.2, Costlow, F., Ed., John Hopkins Press, Baltimore. • Rex, ~ichael A., 1976, Biological accomodation in the deep sea benthos--A comparative evidence on the importanceof predation and productivity: Deep Sea Research, v.2J, no.10, pp.975-988. • Roels, O.A., et al., 1971, Fertilizing the sea by pumpingnutrient ric!l. deep '"'ater to the surface, in Fertilityof the Sea, V.2 , Costlo~, F., Ed., John Hopkins Press 9BaltL~.o~ -~ Rowe, Gilbert, 1971, Be~thic biomass and surface prod~ctivity, in Fertility of the Sea, V. 2, Costlow, F. , 3d. , John Hopkins Press, Baltimore. • Sanders, H.L., and Hessler, R.R., 1969, Ecology of the deep sea benthos; Science, v.16J, pp.1419-1424. • Walthier, Thomas N., and Schatz, Clifford E., 1969, Economic significance of minerals deposited in the Red Sea Deeps,in Hot Brines and Recent Heavy Metal Deposits of t.he Red Sea, Springer-Verlag, Inc., New York, pp.542-5If9. ~arren, Bruce A., 1973, Transpacific hydrographic sections at Lats. 4J#S and 28°S--The SCORPIO Expedition--II. DeepWater; Deep Sea Research, v.20, no.1, pp.9-J8. • Zezina, O.N., 1975, On some deep sea brachiopods from the Gay Head-Bermuda transect: Deep Sea Research, v.22, no.12, pp.903-912 . • • • / /; / -----( '"' /3o • · English Channel\"..-·· • • • • • • • • • • Distance (kilometers) FIG-.1 Diagrammatic view of the North Atlantic ocean floor between Canada and Great Britain. Note the great exaggeration In vertical relief. Om E £ 2500 ! '=l 3500 r ·=t 800 m '500 f 1000 m L_!_ __ ... ----·-·-· ..J--·---~-.J -'- 10 15 20 25 30 o 5 1500m !_ __j_ ____ _ l -_J -_.i._ __ _ ___L__L_j._ -__J__ _ __l..--l...,.__j_____J Tempereture. •c Ill IV V VI VII VIII IX X XI XII I \".rti,ol di•trihution ,,f 11·mprroturr in thr d'"l' •n. (!\lcLcll•n, 1'11•5) .. .., Months of the year .. .. ~ ~l(l,. :J Monthly trmperaturr chan11r• •t various 34.3%. warm water and cold water 1layer of no motionl .....!:._ Polar front sphere -: Currents c=J Salinity < 34.8%. -Physical sea surface level lsohalines --Vertical convection ..• · Cold wat81' upwelling Veloc1ues 1n depth (geostroph1c Exaggeration of depth 1300 -x r: o!l'ponentst: 2.4.7 . .. 17 cm sec·• ~IG. '/ Abyssal circulation. Schematic block diafl'IUD oi deep--cin:ulacion i.a the weaum Atlantic. (Heezen & HoUiater, 1971) (l="RoM MA250µ.m 1900 ~& Piper, 1972 125~2 µ.m 250 Copepod carcass So-416 } Vinogradov, 1961 Pteropod inside shell 910-2270 Euphausiid: faecal pellets 126-862 } eggs IJ%-I8o Fowler & Small, 1972 exoskeletons 248-8oo freshly killed animals 176o-3170 132-. .·~llf: ~m•.111~, J;;;,;;~~~=:::r=:;,~e::::~:::::::::::::::::::::::j=:=:~~ ...'.: 1 .000 f."-''-'-:-"'-;+'1-------+--...,.--+-.,..+-+--+----+-_.---+---1 :·1 · ... ·I ·.·::: ~ ..... : 2000 · .. ... I . .-': ·:: ., 4.000 I g ] I ~ . . ! 6,000 I r--T--1 I I I I ,1 I I · 1 I I : I L __J_.J I I 8.000 I I I I I I I I I L____, 10,000 .....__ __._______________________. FIG . & Schl'mt' oi ven1cal m111rd11ons of the o<>ep-sed plankton· 1, M1!lra11ons oi the surface species: : m1i:,J11ons ex1end1ng ovPr 1ht> ,uri.:in· dnri 11.:insuion zone: 3. m11irahons E'Xlendong over the sunace. 1ran,111nn. • mo uppt>r la""". dt><.')>-l-t"J zoo._., · -1 . m1~ra1oons exr!"nd1ng ovE"r 1ransihon and part oi the~ ....~ '""'" 5. m1~ratoons w1th1n the whole de<.'!>-!>E'.l zone: b . •t'!!ular m111ra11on~ oi some species extending inrough rh" wnu1E" water column: 7. r.iniie oi dismbutron oi ultra-abvss.ll animals. To the leit: vana11ons oi !ht' p1ank100 .ihundance wilh 1nc1Pas1ni1 depch ft~vol points 1n each la_. i~ proponoonal 10 the l>""'''"' 01 lht• pldn~1onl. 1\11nogrado\ . 1%1.1 ~1 • \ ( (f(,. !( . /'-1.1-;:, J..1 ~ jf: I ' :; .. ~) °) 3Wet w1 p1ankton. mg m 00.001 0 01 0 ~ 1.0 1'.) 100 1000 /I?' ·1 ;/· ,....·· 10 I / 2.0-Ii / ,' i 3.0-.' !. ,'I 4 ~'2,'I / 1/ 5.0-~ h .. / I / 6.0-1 ,/ / 7.o-/ I I I .. I I 8.0 (al 0 1.0 c: 2.0 ... .r.· fr 0 3.0 • • • • • et ~1 . • • • • 4.0-I 'I (b) • TABLE 2 133 • GROUP GENERIC EXAMPLE Polychaeta HvalLJ.oe cia sp. -· Ophiuroidea Ophiomusium sp. • Bathypectinura sp. 0Rhiocantha sp. • Echinoidea Echinus sp. Hygrosoma sp. Phormosoma sp. Crinoidea Diplocrinus sp. Bathycrinus sp. • H'.Jlothuroidea Ps·olus sp . Pel·o·patides sp. Me·s·othut•ia sp. Behthodytes sp. • Isopoda Echinothambema sp. Nannoniscus sp. Amphipoda Hirondellea sp. Pardaliscoides sp. • Pycnogonida Colossendeis sp. NY!Ilphon sp . Decapoda Tylaspis sp. Hydrozoa Halisiphonia sp. • Anthozoa Actinoscyphia sp. Antipatharia sp. Porifera Chondrocladia sp. Tentorium sp. • Pelecypoda Phaseolus sp. Abra sp. Cephalopoda Ilex sp. Gastropoda Aclis sp. • Fish Benthosaurus sp. Bathypterois sp. Bathysaurus sp. Lycodes sp. Lycenchelys sp . • Ar~na tha Nlyxine ~>p. • TABLE 2 CONTINUED 13'/ • GROUP GENERIC EXAMPLE Brachiopoda Cr:v:ptopora sp.Eucalathis sp.Pelagodiscus sp. • (Conan, et al., 1981; Grassle, 1975; Hessler, et al., 1978; Menzies, et al., 1973; Zezina, 1975) • • • • • • • • • • 13S • • • • • • f:iG.. ;o The benthic biomass in gm-• at depths greater than 2000 min the Pacific. and Indian Ocean, according to data of the expeditions on the ships Vityaz and OB, and in the Atlantic Ocean according to the data of the Galathea expedition. (After Mf!!lZies. George & Rowe, 1973; after Zenkevitch, 1969) • (FROM fl1£NZ It'S, et o.l ) m3) • • • 13&1 Major features oftM tkep sea =====================================================• Lucif...... (0) Al.to present inLuciferne (NI ........ Low temperature Less than IO 01' 4 °C Shallow sea.a(according to definition)High pressure 50-1100 atm (according Oil-well brinesto definition) Lake Balkal 100 atmCo1111ant temperature Typically no more than Ice-covered seas • ±0.2 degC annually orless, below 1000 mSunlight reduced or ahlent; Less than 10-19 surface Cavesother stimuli attenuated value below 1000 m Distance from primary Several km; primary production , production rcstric.:ed totop 50 m • Lack of or diminishedrhythms, seasonal anddiurnal Three-dimensional Volume 1300 x 10• km1environment, large scale or approx. 6o% ~·ssurface • ( r !~ /: i. ),tA,-f)otJA/.....~ 1 (<175) • • ~II I I ~ 0 • L. /:'IG . IZ Ont~ and saual dimorph~ of Cwatitu holb&lli Kroyer. Adult female, c. 100 cm with adult paras.inc male. c. 100 mm. :"-~ole3Cent female. 70 mm. larval female, 8.5 mm. Adolescent male. oldest freelivmg 5tage, 16 mm, larval male. 8.5 mm (Bertelsen, 1951) t" ro ' ·~_, _ ,u::-~··~-·-i -·-.~~' v'G(TI~ /:1ftl£ 'ARTICL.ES -~....~.... .....-.r·-.1 ·~ j , .,_ ,,,-\ ·, I ...., ,..t!"",,,... i ....,__ f ,,. l "-. 1 ... l '• ; ·~..... ...~ / ;.-v \ ·\... 1 ··"'!,._..... ( :::-i \ '\~~~A J .._( =~ WAIEA. c owff1N '\ °"' ~ (01'i4'aOL..\/E.I>) ·-.... \ "\..... l i:/-~\ ~ 1it;." f J CONTINE.~T/~.,EL.F PRor.> Uc.TI v1 \ ... \ \ ~,.'l ''.,. ~,. -·7(,_,,/ N-"··--" ~. -~{; '. '\ \ \ ~\ z, ·~: l ':..... .1.~ '~ ,/ k. ---\~. ~ i ··~~ \ f)£1"A I l"UYsU\l'iNS10~ \.'··~. -----~ I / l='CSi C>\!A. • ~t /,.?"~ ·--~,~-\\ I_;/)~::~,/// ·?,\ ...· '-<....... ~ 1;1 .. / -~;.> I ~-> \ ~-/ ,,,,, ,,.. ~ '""""'"~."-·"·~~"'' ":... -~ ;f;_..,..,,/. --:-' _.:;';;. Is£I> IM ENTS ~.,A D1Ac:rRAMMATK V1 ew oF ~1c;N1F1c.A~rr 0R<¥ANIC. CAP.&N PAil4WAYS IN IHE O!EP 5~ __.,,..,,,_,.~ll34.3%o warm water and cold water (layer of no motion) _!'__ Polar front sphere -: Currents Q Salinity < 34.8%o -Physical sea surface level lsohalines . -Vertical convection Cold water upwelling Veloc1t1es 1n depth (geostroph1c Exaggeration of depth -x 1300 ·----r:QIT'ponents): 2.4.7 . .. 17 cm sec-1 ~IG. L/ Abyssal circulation. Schemati,c bloclt diagram of deep-sea circulation in the western Atlantic. (Hee:i:en & Holliater, 1971) (,::-RolY\ MACMN4t-~ J fm~~~'l"om Q .... Distance (kilometers} • CD Q1 !. .£ ~ ~ 0. ca=· 0. .... ca ~ 0 ::::> as c: > .... iii iii c: E :::J J:! :::J "(; ~ oc 0 CD c Cl) .... E-.g c c - ~ .Ea: 0 a: 0 8 Fl(-r . 1 • Diagrammatic view of the North Atlantic ocean floor between Canada and Great Britain. Note the great exaggeration ( FROff\ (.;..A.OS'S"> I q 77) In vertical relief• • 25 Om • 20 • 1500 15 p 2000 .; • E :; ~ E ~ £;" 2500 ~ g 0 10 3000 3500 4()()1) ----====----'6'--"00-"-"'-m'--7=-------~ _ 800m 4500 1000 m _ 1___ __ __ ....J _J200m -___ _1 __ L 15 20 25 30 0 5 10 2-1500m I J -_L__L_ __ J.. -__ J._ -l._ __ _L___J_ . _J • .ITemperature. •c I 111 IV V VI VII 11111 IX X XI XII I \"onkal distribution .,f tt·mr•rature in th~ dz50µ.m 1900 Berger & Piper, 1972 125-62 µ.m 250 Copepod carcass So-416 } Vinogradov, 1961Pteropod inside shell 910-2270 • Euphausiid: faecal pellets 126-862 } eggs I 2-18o ~8-8oo Fowler & Small, 1972 exoskeletons freshly killed animals 176o-3170 r I< ·~1 ~ ] I .c f I I c I .._ . ! 6000 1·. I I• r--+--1 I I I I I I I I I I I I I I L __J _..J 8.~1 I I II I I I I I I L___...J10J I ~-&-SC'hcnw oi w:>nical m111r.:i1ions ol tht-deep-sed plankton: 1, MiRra11om of the suriace species; : m1~1Jl1nn~ t•x1t"ndrn~ ovrr thC' '.'oUrt,.U:t: ,1od trJns11ton zonl'; 3. mi1trdllOn!-exwndm~ ovt'r the ~urtace, rr.i•w11011. ,rnd upi1t·r lav1•"' d<-t~p-~l'a zon.,,; 4, miRrallons extpnding ovl'r transition and p.1n oi the df'l.'P· "'•' '""''· 5. m111r.:itl(lllS within lhl' whol(• det•p-sea zone; b. rt>gular mi11ratioo~ oi some species extendin~ 1hrough rht• whol.. waler column; 7. rdn!le oi dis1ribut1on ol ulrra·;ibyss.il animal~. To the left: varialions oi rh<· plank1on abundance wilh 1nc!f'ason~ depch fi~uency ol points in Heh !a~ i~ pruponional to trw hi<'m•"' 01 lhl' pldn~1unl. 1Vi00t!radov. 196 1 .I 1'\,\e.N 'i.. 1£.::· , et ~I) {4 1"? '~ ) Wei wt prankton. mg m -~ 0.001 0.01 0 1 1.0 10 100 IOOO 0 /?~.!~ ,'F-... ' 10-, ~ !,, l 2.0 /i / I I ' 3 0-.' L i ,' I ! I I ~ 4.0:.. 6 4 ~/~.1 ..:.Y 50-./ t ,' I ; 6.0-/ ,/ / ' ' 70 :-/ / ,. . I I 8.0 (al 3Wet wt plank1on. mg m 0.1 1.0 • 20 ~ £ ~ 0 3.0 (;:Ao~ ~A c l'>oNAL!J 4.0~ l'f 15:} • lb) ·-__,_ ,._. ... .~---·· 112.• Major features oftM thep sea Also present in Low temperature Less than 10 or 4 °C Shallow seas ~--""'<;~-+•RCOOH + H20 (according to definition) o2 ;>~ FMN* • High pressure 50-1100 atJn (according Oil-well brinesFMNH2. RCHO (Becterial "\ ---+LIGHT to definition) Lake Baikal I oo atmConstant temperature Typically no more than Ice-covered seas /~:H,_;N • ±0.2 degC annually or less, below 1000 m R.CHO ~20PNH Sunlight reduced or absent; 2Df'N Ox1da1e Less than 10-1• surface Caves other stimuli attenuated f:'• ~ 11 . Bacterial biolumineecence: 9Cbemabc npn9ellla0on. (Adapted from value below 1000 m Ni.col, 1962) Distance from p_rimary Several km; primary production production restricted totop 50 m • Lack of or diminishedrhythms, seasonal anddiurnal Three-dimensional Volume 1300 x 101 km1environment, large scale or approx. 6o% earth's surface • ( fi{'jll' t1~J'i..: be tJAt-fl 1 (<175) • • • !Oma tl; - • i · ··::.~-::;.... .~-=e.··~··;:- Smm Ii ! i ~ r:f' ....,. 0 "" • .· '}.... ..,... _,;:~· · -·--: :--~:.;~w:·~::; L 5111111 l.l. • FIG. /z . . On-and saual dimorp~ of Cn-ati.tu holbMIJi Kroyer. Adult female, c. 100 cm with adult panlSlOC male. c. 100 mm. _A~olescent female. 70 mm. larval female, 8.5 mm. Adolescent male. oldest freelivmg stage, i6 mm, larval male, 8.5 mm (Bertelsen, 1951) I • 7. Coral Reef Ecosystems Tracey Cather, Kirt Shultz, Jim Baldwin I • I. Definition II. Geographic Distribution III. Limiting Factors • A. Sunlight and Water Temperature B. Salinity C. Nutrient Flow D. Substrate E. Turbidity F. Oxygen Content• G. Calcium Content of Sea Water IV. Growth Rate V. Geology of Coral Reefs A. Types of Reefs • 1. Fringing Reefs 2. Barrier Reefs 3. Atolls B. Stages of Reef Formation C. Reef Zonation • D. Sedimentary Components VI. Erosion of a Reef VII. Coral Nutrition A. Particulate Organic Matter • B. Dissolved Organic Matter and Zooplankton C. Zooxanthellae D. Other Algae VIII. Productivity IX. Structure and Zonation of Coral Reefs X. Competion for Space XI. Predation of Coral Reef Animals XII. Symbiotic Relationships Among Coral Reef Organisms • XIII. Man's Influence on Coral Reefs XIV. Bibliography • December, 1981 • • • • • • • • • 7 . CO ~l,d_, ilEEF cGOS y3·fi~t1S Tracey Cather, Kirt Shultz, Jim Baldwin Definition A cor~l reef is ~ ridge or mound, conpo~ei ~redomi~ttely of The most i mportant 0f these or~ ~nisr-1s ~1.rP the stony or herr.Y:tynic e~)ro.ls. ·rhe u1Jr-er surf 1c 8 of' the ree f lies at or ne'3.r ~:e :~ l ev el. 1 =tit ~rtes 32 ~e~r~es ~orth ind 27 degrees south. .Sx tensive c.oral r 0 e fs ,~_ -'.'C f'o1 1nd. i ··: t he C-:1.ribbe1."1 Sea , on the ~~ist c o .:J.S t of -~frica ·r ni:-:l '!.'T'eatest den:1.s ty of reefs is l::-1 t i:1e easter n b ·: !:t r~:~.vigablP ch;:;i,·:_nr~l oaralleling the co:?st. All co.r8.ls reefs cor:.ti ne'TSs 'L"~r1 <~~e '.bscnt fron: the west co 1_s ts du(::. to the up:.Yelling of col~ cu~rerts ~d thR ~bsence of lSUitable bR s e for ~rowth. ~ ,..,nortq~-: t. co-r-d ::r·c,e:f s ~-re restricted to :.re j_s t'!h ere the Via t er occ·.\lI's '.Jstwe 2 "1 '2 ·) : "' 1 ? 9 de;.:r ree s Cel s i -J_-:; • 3unl ight •• 6C \ \ .;., ·~ t..-c \ \ (;C ---....---+-----+-----.'"--· -Abundant· reefs -., Atolls -tr C February r figure 3-14 ·1 *•> 'j \ Distribution of coral reefs 8ftd areas of abundant atolls. The contour lines ...-=; "'-~\ show the limits o1 wa1ef'S that ne¥er get colder than about 1a0 c. ·~ ,). • .......... ~ • is i ~rrnort:J.n.t to the photosvntheti c -~_cti vL ty of zooan_thellae which have '.1 s\P·•biotic relatlonsh.iD with the cor·3ls. .rhe coral reefs • extend '~ ee.Jer in morP tra~sng,rent W;=lters. Flourishing gro\.-.;th does not occur below a 1epth of 180 feet (40-60 meters). 1 Other i nport lnt li~:itinv fact~)rs :i_ v1cluie s ·1lj_nity, •mtrien~ supply, • wa ter circulqt1o~. ~v'.1libility o f a s uitable ol~tforn for growth, turbulence, oxy .•rc:::·.ri ·1•1d calcium co~tent. 3al1Yli t;z 'The salin1 ty of t 1'_'ou1cal waters 1-n whi ch reef cor::~.ls h .03.Ve attained their :·'laxirrium. developement is about 36 parts per thousand, which i~~ a J;toderat:;ely h1.gh salinity for sea wat(~::.'. V!ery f ew observatJons hn.ve bee~-.. made on the s:=i.1i!.1lty tolerances of corals, but it is k11owY'I. t'-1.at species l.ike those of the p;enus ,~cropora, the St'1.P;horn co·~·al~ , ean toler ·1te a :rise i n salt:ii.ty of only 4 parts ner thou.Qarid for 12 hours. ·rnese snecies :·1re also ver~_r sensitive to te":perature fluc ttF:.tions. Han:•r specj_es a!'e able t o '·"ithstand tncreases in salj_viity up to 12 parts per t 'c10usan.d for 12 hours. ? ".Y11 can also t ol er:::lt e a drop in s a linity f or periods up to 24 ~ours. Nutrient Flow • to t. t·1e st:1t ;_ on-:t -:.--y cora1 s • ·-:; ubs tr.· .:i.te Coral reeff') r·pn1li re -; solid substr '.te f0r growt11. Corals do not n·row on v0rticle cl iffs• S'Jr'.e kind of bench, pL1tfor r.r or shelf is req1 Jired f0.r .•"ro1·rth . ~h:~_llor~1 conti:1eri~aJ.. sheJ.vr.: ,: ::re conc.·acti.ve to reef devel oDei'.-~e~t. The cr1.ti.ca.1 po:int t ,~ r.he ::-;i;:e ;HJ d_e -9th • of the pl·i.tfnrr·, "":'elative to the p~1ttern of sea level rise aYJ.d fall. • Turbidity The need for i suitable platform r 8stricts coral reef growth to ~1.reas of clean 1.n t'.?r where the bottom substrate is not muddy. • For exP..nple, corals do not grow near river rr.ouths where there is a hiP:h influx of s edi;.i.ent. (Some s tudy s have indi. cated tha.t the rtecrease in salinities associated with river~outh waters is most • lik~lv the princi nle ltniting factor for cor-1.l '?-;rowth, rather than ~ilt i.ccurmlation. ) .Although corals have ·:1 sur prlsing ability to .rPMove sedir~ent fro1'.1 their su~faces by ciliary act:i.on, .they • c~~ ~ot cope with lar~e qu~ntitieq of sedime~t dropped of .the Jowi-:r brat1che~~ of the coral colont.es. ·rhE coI.. i.l ·~ will eventually die if ~edimentatlon is continued. Coral specie~ with larg e • .polyps ~re more efficent at sediment renoval than tho~e with smaller polyps. 0Xyl7 en Content • Gorals are i n f!:eneral, tolerant of eonsider;::t.ble lovrering of the oxy9'e't1 saturation of the water in which t hey live m d show little ~hn.vi.?:e in their res-oi ration rate until s a tur::J.tion has dropped • bPlow 8.bout 50 -cercent. Those species thqt ::.re adapted to live ~ n sha11oi:•: water ha M.tats , ~1Jch B.s "?OOls, a~~e mor:'e resista-'.! t to f 1,:te t w -1 tions i YJ t 1-;, e .->x: '.' ··~~en cont ent of the w · t er th.3. ·1 t nos e .s peei es • characteristic· o f deeper water. ~...Jhere circulation is r-estricted, t;J1e o:{/p:en content nay fall very 101:r ·.;_t n\ s ht wi t!'lout f.-.;,tal results :'or the corals . Other reef j_nhabita~1ts rr..-._1y not s :ffvi.1."e .. • C~lciun Content of Sea Wate~ Coral s require a relativeJ_y ~li~;~~ conc~iTt::--: . • ratf~ of 1_ cor-3.l r t-?ef is in the vicinity of 1'-k'lm per year Dr .5-1 mPters· per lOOO ye~1~s. The u.pw _:;.-rd :~rowth of coral2 s tops in the neighborhood of 1011r , .r.~·::.termark, the exact level vary inc..; with the I snecies a~d habitat. Growth is greater ~t a sl\ght depth rather than clo.se t i) the surface. ·I'here are definite tendencies for colonies of vqrious species of co~al to ffi iintain a more or less circular outline. Growth is sreate~ on the lesser diameter of the circ ul a !' co1onv th~-,-~ on t he ,cz:reater di::ir1eter. When p:;;.rts of a • • colony a:r-e broken off, t11es·e parts tend t:.o regenera te faster t •lan • the rest of the co l oriy. Young colonies g ro·w faster than old colonies . Ge0logy of Coral ~eefs • rrynes of .lli:efs There are three general types of coral .r1.:;efs. According to Char1~ -; D9.rw1.:: ' ': ·Theory of <3ubsidence, these ~~_re ·111 s8na.ra te • bu·t re1ated s tB.p; e ~ of reef f o rnation. rh e three t .Y:Ges of reefs a re : 1) F:r-i nging 3eefs, ·which forPls borders· just along the shoreline of continents and isla~ds. An example of a fringing reef is the • Hawaiian reefs • · /. ' 2) Ba~rier Reef'::::,. which qre found further>3.!'1d separated fror.i the shore by q lagoon. An example would be the Gre~t Barrier of • :\us trali a • 3} Atolls, which are ringed shaned reefs from which a f ew low islands project abo7e the sea surface, surrounding a lagoon of • open water• Star~e'" of Heef Formation (:figure 2) furwins Theory of SubsidPn~e i s prob9.bly the best theory for • ex~laining reef forr~tion. Within the tropics, newly formed · volcani c t s1 ·:J.!1~ ~: ( ·.:..,-:10 c::ubnerged volcanoes that al:r~:ost re>lCh the 0 sea ~urface) 1re 8Ventu:3.l ly populated by cora l larvae from other • nearbv coral islP~ds . rhe larv;.1.e settle :-1Yld 2'.ro-:·T ne'.:.~Y' th::~ surf::tce "1.nd close to the <:;}'!Ore forning 9. fringing reef• rrhe 1:ieight Of the exD·-1.r:ding reef, as well ·~.s the i:rnight of the volc'.1-noe its~lf, • depre.::~es the ocean floor 1.nd the i .sJand slo,~Tly ~nnks. If the ilDw:~rd t~~:rowtr. o:' the cor~'3.l reef k:-:>en .c:; ci.ri ce ·,·.'i th t:-i0 s i::iking island, • Reef Reef and reef detritus ngreef~ • Reef and detrihs -I !!.j I (l ~. C\ ·E> ~ I\ v~ ~ +,.I i I I I l \J j I ,v iO 0 +.-I 0 :::l I I fore-f'ftf --I Li ~ '~J~ '(\j ~.... c t. I \J ) r\ ~· ~. \') ~~ -.. ·'· ·:t ~\~~ . . ' ! I I'; ! r: ; ~\~, \ :1 . '· \,) -1 f: ,-~\ ~ . .:· 1; ~ ;J \-! \• 1 ~i \.'1 ''j! I if ' \, l t:..._ \/ rs~ ~ \ ..... ,,__ I ~)~ ~ : ! jr ./ 111 ~ w~ I.,./~~}, \ I If i I ~(.~, .V: /1~' I . . >'/ 1 :( \•\;,,J-,., 1, ~ !L:P ~ ~ ~ "'( :; IJ\.~~ ~ "'( ~/ ! +,.. i I I j I /,) ' u; a & • IS/ • the reef :;i'1k~ 1-·Ti tr. th A subsldence an.d dies . :\.s the isl-?n1 sl nks !Way fror'l the c:rowi np; reef,, rnany-of t~1e r:iass:i.ve c.oral ::: left i n the qui et waters bp(lj_ 110 t h e reef dt e. 'rhey ·.-.;,re soon covered with reef • rlP.bri s to for " a s !1a11 ow l::lf:,Oon. Thi'~ "is nav: a barrl er reef. Wt th further si~ki~~ . t~e volcJntc core of the islqnd n~y 1isappear CO'i'.!DJ.etely b eneat'-1 t.~ reef cap :1nd leave behind '-;_ Ch,J.in Of low • J~eef Zonation \ ty-nlcal :rt:;pf' c:·p1 he divided into th::."'ee dist~. ·-1ctive zones,, • side of the r eef. • 2) ;~PhP .rt; f'•f' crec!t is the hip;h point of the r r>':f 1.1(h1~h is exposed to :11. r ·3. t 101'." ti r~.e. It extends fron ~:;ea 1 evel to ·, d.epth of a fei·J r1ete:rs (7-10 ~ 1st>~rs). rhe reef crest has ~:i. 1nttress zone • whleh absorbs wR.v~:. ?. r·er~y and protects the reef f:rom (lar'lae;e by breqkers. '3) ·rhe fore rer:o f' j_s subdi.vi ded L1to: • a) t i-i 0 fore n~~~·f terrace, whi ch i s E;entl~r s l oplng to a depth· of 7 to 1_5 t1f:'t ers .. • c) the c00u fore reef slope, which dips ~ea~~rd to about30 neter:~ o d) th(7' dec~o !''ore reef. below SO to t.~f" ~::et er(; , which dropsoff abruut.J:v t c) i 1'l~c~1:eri.s of 1nPt crs or 'rJ:.~t1~ r:· .ieut!'-: .. • 3edi ment · 0.17 r:o ; :poncn Ls • '.lt.o•lo h 111 l,1111 l1•1 1f, 111111 llH•f 11h1p11, lllld d···~P '"''' 1t:d l1t•111 tho pv1:.µm:&lvo ul a '1 1v1:r ;11 ~O mt~lors doplh. Fore-roef torrace ; 111<1 f•:.carpmont ~ro seen at upper left, ' "''~l'"!J 't'tith loru-rc~r slope. CorJI pinnacles dot tho lore-reef slope and large pinnacles 11s1~ ;ibovc it to become promontories of tho d1~ep fore-reef. (Skotch by T. F. Goreau.) / I .. II / / • J I / . , , \·'--·\~ '"··c··· · .... .... • .· -;__i •. . \·· . s .\ ) . ' ~ /: Y. I ~ Prevailing winde .. ~· · \ .., \· . • 152 • • • • • • • • • • • /5'3 I. cqlcareous al~ae. This forms ~n onen cavernous structure. Loose fra:ne buildj_ng co:-.:-3.l skt-=;letons bound toD;e ther b1 e··1.crusting carbonate nedinents are derived. from the ~e~e:-,,y 8.:1d di s in.tehration of corals, aL~ae an•i other c.s.rbonate secl"etJ. ·v~ or.:~::-1 ···11 ~1!:1s on the • reef such .·1s single-r.elled foranini fer;:·:.r.;, nollusk shellD, ;:vLl <;ea as 4 to 22 percent of cor·"ll. reef sedirte:J.ts.,. • '='elves constitute 15 to l.}O percent of coral ree f sed:i.nents .. • so1 :1-d carbonate mass., :Sediments accumulating on a nd ;-':',,ear the coT.aJ. reef are entiTely of skel eLd Zooxanthdlae and india ink Into the • F.~:n~:-_ __ • .epide~is zooxa.nthellae ! amino acids '':_<;~ w · Sclcr.l<'Linia. ' ;~"\.. •j dtt } · Hermatypes: ~,a.~,~ Fungia + g·---:""& + ++ S:_vt11plwra + +++ ++ ++..:.-+++ !'ff'f~~· _.\h1·n11atype: +++ +'.f-+ ++ +++ +-r +/'::bastre.a 0&r,r·:.I Ak\ ..:·.acca: +++ '.i ~. +f+ 0 +++ +++ ~; o-:-- + i 0 '' ~ +++ 0 fE:~ ~ . 0 ~ ~~~ . + i ? ~ L -1 +++ ? disordered 0 + ++-t-? + ++..L ... 5 ~ P. ~mndis -!-+++ . ? ++ c D + ++-+-++ "'.,."'':r"~ ::r "' .. g~· OtrLr m11rplwlagiwJ <'Orrel/atn with xamhel/ar s;m11>iom an;{li Xenia : no nt'maio1·ysts, reduce.ti filametJts. no srptal lobes, 'f> ~~~[..~ ,-'' It '·~41 (2) Zm nthus : 1umatocysis. but these 11re in a disordered position and in places u.•hu'! tiu:_-,, do no J:O(l(l: -y ...,i :';"' "•:" l !i.fomurts redttctd hut lllbes arc «rry larg1-. Alt stages •!f pyc11.osi.;, der,enerotion, fra gllllR ~3 "-. : Frrdi11~ re111:tion: mentatian and extmsum of ::.noxar.thetlmt were ()0.'er:it:d in zhe mesenu-ri.ai. lobes.~ ~ ~-,' .. ; {I: Ca.rais: c r: I\ · Dilation and extensio-n !>f stomodeum, imbibiiion of waler, somelimes ert:nim of ...,. "'~ Jer.:acles "'shooting ofthe ;nesenteriu through mouth o;bt:>dy waU; !'!.x ~· ::,·niids: '"::; ;::;' Rhvthmir 1n01:~ntoftenlaries of anthocl'Jdia; ; ' E "' r: ~ ,;: ••mtilids: Zo~nthus sociatus: i'w1Je, .. ~8:.~ Palythoa caribbae: Dilation of moul/t., stro11gly in-.;:ard m<111emen' {If ".;.'Yl/.er at cilict"groO'C'e, curling °"~ of the tenlacu.iar rim, Fig. a. Oiagr:uns indicating the modes of feeding in hennatypic corals. (A) t·:upliyt1f;;. with large polyps and all cilia beating awat. from the mouth; ( B) Pocil Paiythoa grandis: same as P. caribbae. ·~7·9"~~·· · 'opo1'a, with small polyps and cilia carrying particles up tbe cofumn; (C) ;.\-teruUna, 1 mcandrine with short tentacles and reversal of cilia (resultant current indicated by +~· er-u({.f. t -- )roken arrows); ( D ) Coeloseris, with all particles carried by cilia over the mouths ·or ingestion if edih!e and removal by water movements if not; ( E) Pachyseris, ([) nouth.~ in rows \\ ithin parall..I grooves; no indication of tentacles but food collected 'Y mcsenterial fi!:1J1,.·nts extruded through the mouth. Magnifications vary. From t~. longe ( 1968). .f.\. c. u~E «.L..\ ~ () • /(pf • ·f. Nulrit im1 of (:om/.v Hl • • A B • • c D : ', ' It'"• 7iJ&E -. • E • Fif!. I. Dia.~ram.s i11clicaling thc1 nwod/f,111om, willi .small polyps and L'ilta l:arryi11~ partidt'.'i up llw <'nl1111111; (C) Ml'f'f1li11t1, .1 1111 ·a11dri1w with short lc\ntadt\.'i and re.vl~rsal of dlin ( rn.rnltnnt curront indicated l>y I1r11kt'11 arrow.'\); I I)) Cooiosni.,·, with all pa1ticlt~ carrit>d by cilia over the mouths f, 1r i11g1·sli1111 if l'llil>lc· and n·moval by wakr mov<~nwnls if not; ( E) Pru:hyseri.v, 1110111h.-; i11 r"w.s witltiu parnll(•I groovt•s; no indication of lc~11tadci; hut food collcctc~cl 1._,. 111'""('11l«'rial lila111f'11ls extrud1!d tArough the mouth. Magnillcotions vary. From foug1· ( mos) . • • • • I STRUCTURE AND ZONATION .Q.E CORAL REEFS 162-w Wave force, water d€;pth, temperatuPe, and salinity are the major environmental factors that influence the zonation of coral reef inhabitants. Hermat:;pic corals and coralline encrusting algae(both • reds ans gre:ens) mahe up t.he bulh. cf the reef itsc-lf an.dare subject to both horizontal and vertical zo:i.1atic.:n. Jn the deeper, ctiR!!.~'J. lit\te:ns • tetween about 150m and 30m below sea level is the outer reef slope. O~ly a few species live in this area, mainly due to the low light levels present. The deep stony c~rals fcund here adopt a broad,i • flattened form whic,1 probably increaset. their light-gathering ability. Also found in this region are soffie fleshy sponges, coralline spcnges, e&.nd gorgonians. 'rhe rest of the reef s 10pe, from about •50n to ..2Cm, • receive plent~ of sunlight but are below the zone of wave influence. This area includes manJ' of the delicate branched corals. the butress zone extends from about 20m below the surface to just below the low • tide level. This area is strongly impacted by waves anu is dominated by nassive corals such as Montrastea, Diplora, Porites, and others. Horny co1·als (gorgonians) and hydrocorals such as hillepora (fire • coral) are also prorninant r~er!. The reef crest or brea~·_er zone often consists of an algal ridge. A few species of calcareous r~~ algae, crustose cor·alline algae, an~ larg~ fles1Jy algae are usually found • here, a.long with a conglomerate 0i' corals and bioclastic debl'is. (Glynn, 1976) This zone suffers the full foi-ce of the breaking waves but tht encrusting algae produce new reef materials as fast as the • waves erode it away. (Sumich, 1980) Behind the algal ridge is usually founj_ either a reef flat or a lagoon.1'his is usually barely ~over,,d by water at low tide and ex;>eriences i.1inirnal wave action. This envira:-;-.·.: • ment can support an immense variety of corals and associated orgs.n-t isms. (Glynn,1976)(Sumich,1980) Figures 8 and 7 illustrate the typical structure &n.m zonation af reefs of two different areas of t'r1e: wbrQJd:\ · .. • • /(JJ3 :,:. Zonation of cor·a.1-associated plants anti Animals is much less well defined. The butrass zone provides a habitat fo~ almost every kind of small fish associated with coral reefd. This in turn brings in the• larger predatory fish such as tuna, sl..arks, jacks, _and barracuda. The algal ridge provides a habitat f or only a few snails, limpets and urchins. The reef flat contains the richest and most varied population • of reef dwelling organisms, including the giant clam Tridacna, and a large number of echinoderms, crustaceans, mollusks, anemones, eorgonians, and other· animals. (Sumich 1980) Sometimes seagrass beds of• Thalassia and/or Serangodium grow in the reef flat too.(Glynr~ 1976) Th~ fish of the coral reefs can be roughly categorized as follows: • 1) Reef-restricted fish, 01" those who depend solely on the reaf for food ans shelter; 2)Reef-related i"'is!1 which use pn t of the reef every day; $) Reef-indifferent fisri whi~h include the reef as only a small part of t;heir daily range; and 4) Non-reef demersals which • • aren't directly associated with the corals but use the sandy substrate around them as a source of food and shelter. (Parish and Zin;merman, 1977) Figures ~ and /9 illustrate son.e of the fish associatea with • different areas of the reef. COMPETION !:Q!!. SPACE Space is tLe major limiting factor for growth on coral reefs. Thu faster growing corals are usually opportun1stic and will h:e-:.~:;the.x1'~1.-rst douinant organisms in an area. Tbey usually aren't as well adapted to • shanging conditions as are the slower growi1~ corals so the slower • growing species usually control the popul~tins. (Grassle,1973) Somt slow ~rowing scleractinian corals can extrude their mementarial filaiLen.ts and digest the tissues of the surrounding corals extra • coelentrically. (Lang, 1973) Similarly some cora,1iito.oppnil.an ,·_ c·ollals ·ean kill their neighbors by using special marginal tentacl es which have greater tl1an nor mal d~tlsities of nematocysts at their tips.(den uo-..... +l"\cr 1077' ~nmA qoft corals of the family Xeniidae are able to move t:) colonize n.ewly available space. Xenia macrospiculata for example, • uses its' ability to climb .'to,; settle on the living tissues of stony corals and competetively exclude.:: them. (Benayahu and Loya, 1981) • • • • • • • • • • PREDATION OF CORAL REEF ANIMALS Coral predation is practiced by many groups r.[' anirrnl s . The c.ul't:..l jtself has protective mechanisms such as nematocysts and sharply projecting sep~~ with serrated ~dg~s . (Glynn,1973) These don't always discourage predators however. Many fish are coral grazers. Scarids (parrotfish) and those chaetodontids (butterfly fish) which are facultative coral feeders bite off polyps, scrape the coral, and bite off the tips of coral branches. (Patton,1976)(Reese,1977) This method of feeding also provides a major contribution to the sediments of the reef. This was first noticed and commented upon u~ Charles Darwin on the voyage of the H.M.S. B~agle when he examined the intestines of two species of scarids. Those chaetodontids which are obligate coral feeders and some damselfish also feed on corals but they don't damage the coral skeleton. They feed by "sucking" the tissur using thei1• fleshy lips. The damsels are also very territorial an.d often "tend" algal lawns which grow on ·· "their" coral heads in areas that they have ot~er killed by feeding upon. They protect their coral heads from herbivores but the killing of the original tissue also allows boring sponges tc1 invade the. head ..Jhicb then weakens the structure. (Reese, 1977) (Kaufman, 1977) Prosobranchs gastropods and nudibranchs also prey on corals. · Proso~ some remain on one colon~ branchs can act as wandering predators but and in so doing, adopt an almost parasitic existence. They can destroy up to 2!)% of the annual growth of a colony although some also :~eed on sea fans, sea pansies, and other anthozoans. (~)atton, 1976) Nudibr&.nchs, on the other hand, feed mJstly on al gae , detritus, and hydroids, bJt also a little 0n corals. They have the ability to eat the ne~atocysts • o: their prey without dischargin~ them. They then incorporate these 1. • , nematocysts into their. cer.atae and use them in their own defense. • (Barnes,1974)(Gross,1978)(Surnich,1980) • Some crusta~eans prey on corals.Majid decu.po1s lika the spider crab feeJ by clipping off the coral polyps with their chelae. (Patton,1976) The must publicized ex~nple of coral predation is by the echino~erm Acanthas ·~er planci, the Crown-of-Thorns starfish. Since the early '.}Q~o 's there had been a population. explosion of ~· planci in certain areas o~ e the Great Barrier Reef of Aust;ralia. These sea stara crawl a.bout the reef &.nd to feed, they stop and evert their stomach over an area and digest the coral tissues. This feeding method als~ results in the deaths e of algae, sponges, fish larvae, and otner small organisins due to the digestive juict-s released. Acanthaster avoids the corals' defenec mechanisms by using its' arms and spines tn cra~l around ratrier L~an e the tube feet •. (Endean,1976) Sorr.e think that t.1ese populations are periodic and part of the natural population fluctuation cycle. Frankel (1977) made a study of the remains of bcanthaster in reef sediments e tha.t possibly supports this theory bu.t Enaean(19Tl) refute,s this theory and cites a la~k of real evidence. He also points ~ut that there is no mention of such outbreaks in the records or folklore of the native e people. Endean favors the hypothesis that human removal of the giant . triton, Charonia t1~itonis, a.nd the groper, Promicrops lanceolatus, W.l..ich • prey:··upon juvenile Aca.nthaster, allowed more to b~come adults and breed, yielding even mure Acan.tha.ster·. His report sr... ows that human rem.:wal of • the triton and the grioper are in a(_· cord with the histo1·y of and the areas of infestation. For this reason, he says that the population exphision is a unique event. Some other echinoderms, sea urchins for example, also take coral tisf.ue as a part of their diet but they don't cause the same exte1•. t of destruction • • Only a few anir1als will prey on adult Acanthaster. Of these, the /(o(o painted shrimp, Hymenocera, probably does the most damage. ·#/hen feeding~ • a. pair of Hymenocera may team up and amputate an arm of Acanthaster. Then, the shri::np follow o~ r·ide 0~1 the sea star while consuming part~ of its gonads and other internal organs and tissue. This n.ay or may not • lead to the death 0f the sea star. In attacking, the Ehrimp intereferes with ti.1.e feeding posture and stomach eversion of Acan.thaster .whicn results in a feeding rate that i.... 1/3 ·or the nornal r·ate. Hyrnenocera • probably W•Jn 't make a good source of control of Acantha.ster, mainly because it ;J:re:~er-.-.: ·.·; the:i ~steroids such as Phaturia. and Nidorellia. • It usually only feeds on Acanthaster if its preferred ·food is scarce or absent. (Glynn,1977) Other echinoderms are also preyed ~pon. Echinoids are mainly preyed upcn by ruddy turnstones(Arenaria interpres) • reticulated helmet-cowr·ies ( Cypra~£,~ssis te~~~~~.~1.:1-~J, and porcupinefish ( D1odon nys t:r~ i.x), and other urchins. (Hendle..1.1 , 1977) A few e~~amples af other predator/prey relationships i~clude cephalod ;i1 eciation of snails, crabs, and small fish.,, fish preying on invert·ebrate reef residents such as the se~ cucu.mber, which will eviscerate its' g0nads and part of its respiratory tree if provoked. This provices the fish with a nice meal and it then leaves the sea cumber itself alone. The sea cucumber later regenerates the lost parts • .(Barnes, 1914}..,Fis.h also prey Qn other fish. Some of the most obvious of these are -~he • barra~~~a, tarpon, eels, and sharks. SY~1EIOTIC RELATIONSHIPS AMONG COFAL ~ORGANI31'-S There are many, many organisms that exist together in some sort of symbiotic relationship in. the reef area. Symbiosis is defined here aE a prolonged, close relationship from which one or both of the organisms invclvE:;.d benefits. Symbiosis can be divided into three basic form~. 1) Mutualism is a relationship from uhich both of the partici~ants ben~fit. 2) Commensalism is the form in which the symbiont oenefits but tb~; host neither benefits n 1.::>r .is hurt. 3) P.i:..trH~.itism is a relation • /(.p 7 ship which is beneficial to tt.1.e sy:nbiont,·and detrin:ental to the host. There are many organisres that are symbionts of the cor&ls themselves. Probably the most important mutualistic relationship of the coral reef • is the relationship between the corals and zocxanthellae which was disc~ssed earlier. Most of the meio1aunal organisms are parasitic tc corals. TnEse include ciliated protozoans, small f'latworms~ nemat0des, • boring sponges may also be parasitic. They and copepuds. The clion~d or sometimes extend filaments up through the porous inner skeleton of the corals and take nutrients fror:-1 them. These ~ponges usually enter liue corals through the dead base Uut they sometimes bore into live tissue, causing localized polyp death. Some other· representatives of the I Porife1~a live in•cornmensal situation with corals, in. whieh the sponge • gets the benefit. of having a solid substrate and tne coral isn't harmed. The sponge Mycale is a mm;ualist in that it ft causes the plate-like corals that it grows on to develpp upturned folds. The sponge benefits on. • by receiving a constantly increasing substrate area to grow The coral benefits becuuse this sponge lives on the dead underside of the coral and prevents boring sponges frcm entering• • • Sipunculis and polychaete worms are usually cormnensala. They appear to bore into the coral (a few actually do-Barnes,1974) but usually the~ have just been "grown around" by the coral• $ome gastropods are also grown around by corals, :f!or example, two organisms which ap~ear to bore but don't are the vermetid worm snails • which merely extends its tube as the coral grows and:·iMagilus which just extends its foot as the coral grows. • 'J.nere are some commensal bivalves (Pelc.cypoda) too. These are usually grown around too and have to burrow outward to k~ep up with coral growth so it can keep its siphons out in the o~en water. There are a • few parasitic pe~ecypods too. Some of these burrow into live tissue /(p 'I· • • • • • • • • • • • and some take nutrients or even zooxanthellue from their host. The cirripedes (barnacles) are also usually corrL."'llensals. They settle "accidentally" and are overgrown so they usually just extend the plates of their shell to keep up with coral growth. Hoekia iuonticularia is an example of a paraj'itic cirripeda that €~ts any coral that tries to grow over it. Symbiot.ic decapod crustaceans include the a.nomuran crabs which are parasitic and scrape the coral tissue to feed. The gall crab, Hapalocarcinus marsueialus is a pa.rasite that becomes trapped in a gall that it causes the coral to form • It then feeds on coral tissue an.a. zooxan thellae. The potonin shrimp, Paratypton siebenrocki also gets trapped within coral but it is a commensal prisoner and eats only plankton. Many organisms use the corals only for protection. Some gobies and damselfish enjo~ a ~utualistic re:ationship with their corals. They ~~e very territorial and in return for the protection they receive from the coral, they protect the coral fron_ invading organisms (including Acanthast~er) by eitner attacking or eating t.i:iem. (patton, 1976) Some animals us3 corals to protect their eggs. The cuttlefish, fer example, has been obse1ved to place its single egg deep within the b~anching arms of a large stand af Acropora. (Roessler,1981) ManJ non-coral associated s:rmbiotic relationships may be found in the reef a.roa. A few examples of the more well kn.own occurene;,0s are summarized here. Some hernit crabs, for example, will carry an anemone around with them on their shells fo1· r rotection. 'I'hey will even go so far as t o move the a.nemorrns to their new shells when they have to fi.nd larger shells as they grow. Likewise, some decorator crabs will place pieces of sponge on their carapaca for camouflage. (Barnes,1974) Two examples of c0mmensal relationships come from other animals that use anemones for protection. Two shrimp of the fariily Paleomonidae, Periclemenes rathbunae and P. anthouhilus can acclimate the anemones tv their :_, ~-:'r.~_: ·: ::.:., /(pf:/ • presence, or vice-versa, .i.)ossibly 0y acquiring ane~none mucus on their integume1its. (Lvvine and Blanchard,1980) Two sp~cies of cardinalfish are also known to hide within the tentacular sphere of some anemones • • They, unlike the t~1e clownfish, are n;)t immune to the nematocysts of the anemune and must avoid touch:.ng them. (Colin and Heiser,1973) The clownfish Amphripion, enjoys a mutualistic relationship with its anonone. ·• It is not actually immune to the fiematocysts but it appare~tly has a chemical factor in its muc~s which allows it to nestle among the tentacles without discharging the nematocysts. In return .for this prn~.et1 01 1, • the clownfish acts as bait to lure other fish to the anemone. On · occasion, the clownfisa n.ay even collect bits of food for its a.nemcne. They hav~ even been observed to catch a fish ~o feed to its ane.mone • • • (Sumich,1980)(Colin and Heiser,197J) Another example of an animal that uses an.ocLer for protae;tion is tr""e shrinJ.pfish,Aeliscus, which is often seen swimming head down among the long, sharp spines of the se.a urchin, • Centrechinus, (Sumic~1,1980) Two .L;1ore examples of mutualistic relat,ion.ships are those of tne cleanerJtti~pand cleaner fish which clean uther animals, The cleaners benefit by getting a meal and the other animals • benefit by the remov&.l 0f external ~arasites and damaged tissue.Cleaner shrimp of at least 3 genera are known. Some of these attract fish by waving their flaglike antennae. These are known to clean fis~ 1, eels, • and even spiny lobsters. (Bruce,1976) Gobies, .. ;rasses, bu·vterfly fish, and yo-.J.ng angelfish are s.mong the fisL Jc1c wn to set up clca:i...ing stations, The wrasse, Labroides, is also partly parasitic in that it somet imes • takes healthy tissue too. There is a blenny, Aepidenotus, that mimics Labroides in color and behavior but when a fish ai:·proaches 5.t to be cleaned, Aspidenob..ts attacks it. (Sumicr1,19(.)0) vne ,)f the few examples • of parasitic fish is found in the needlefish, Carapus. Thi~ fish iLvades the intes tina.l tracts of sea cucumbers and scmetin~e s . the stmnachs ol certain sea stars where it :eeds o~ the host's gonads and res~irator~ /70 • • • • • • • • • • • many, many rr:ore exar,y_;les of ..::.ym structures. (Sumich, 1950) There ar·e biotia relationships on the reefs, and there isn't roon here to illustrate them all2~ut this has been d fairly representative sample. MAN''~ INPLUFNCE ON CORAL p.._:;EFS Mans' reladJ~o:1ship is a very impurta~t part. of t.1.1€-interactio:n!9 ·..; .. th# coral reef ec o ;.,.,ystern. To man the cural reef_can oe a vep -y §ignif.,., ." cant resource. It provides t, bas is for both s11bsistEnce and commercial tishing, tou.ri sm, and recrcatLm. Reefs also provj_de proteation fol' coastlines and harbors and pro·1ides a source of materials fo~ beaches, cons~r~ction, handicrafts, jewelry , and curio8. Natural influences include waves, storMs, epidemics, an~ natural deJulopment ana succession of populations.Tcic little work has been done to be able to differentiate ~)etween natur&l infl~er!c.es and rnan 1 s influenc€ all of the tirne. It goe :J without saying that it is very di:fic~lt to predict the outcome of things th&t man tries in the ocean env i ronmert. The AcanthsstLr population. E..JCplosion should l;e te.kc.n as a warning to man to cons i der very carefullJ and thorc)ughly any manipulation that he undertakes wi~hin the coral r€ef ecosystem. _____, ~41fltl 1:011111llClUllllR • -···· 171 • .. I 6 . ~.~ ·_-------------·----.. ----·------------- ----------------------·------. -----------------------------·-----. ..., ~•~AY~~~~~--~~--------------~~-+-~~~------· • '"" ...,._CltlSf ,__.. • fllONY---- • \ • • - ~ f;. ~? • 1~'11t'faliscj pM,:turcs. indi~atina 500\C of the OlMC char:tClCt• \ l1~· li"h spci.:ics. and the different habitats they o~:cupy on a .c-.1 ward r\X·f.' S.11ldy-alg;tl-ruhhl~ and b,luld"'r Z\lllC. ' Ik:q1 i.:oral JlO,lls., sur~ channels and the. surf zon"' aluna t lic outn c~t~c ,,( a red. Adapted after Hiatt anJ Strasburg (1960). • • • THECA • A Ty,1c._., Co'ML Pot.VP 112. • • 1. • • • • • • -Fis. 'I 1. Butterfly fish, Parrot fish. Trigacr ftsh. and Puffers are amonast rhc species most c:ommonly found 1razin1 on larae massive corals such as Porit~s lut~a (c.f. Plate ..). • 2. Herbivorous fishes of the reef flats. 3. Fishes usually found associated with branchina and plate corals. These fish are not all coral rec?. z~:v:i1o~y. ;:)111.l:1de?l. -ohi:u . ;.~ .. H.. _; ;j_unde:·s Co. , 19714, Benayahu, Y. :1Y1d I :·J ya, Y. ''Co;rneti ttcv~ f.'(1r "3p·1ce: ·~1flOU~'"lg Go:·;;;.} Reef Sessile Organisms ::it Si la:~,. Red Sea • . Bu.11. Sci. J1.(J). )1l}-_52?. • • Bennett·, Isobel. The Great Ba.rrl er ::ieef. Lel. bou:cne Lansdo·wne T-re r::; (.;, Ltd.,. 1971. • Bruce, /l.. J. "-Sh:r1_rrp and Prawns of Coro.ls Heefs, ·.:;i th Re?eren.ce to Cor.J.mensali sm." Eiolofzy ~ ·1d Geology Ti.eefs. ~,..-oJ , j. ·::d • .Jone~; ind. 3nd.es.n. ·1_ 976, Marine JOGO;: 1peci ·~l of Coral Co.l in, P. L. ~1.nd. ,J. ~S . Heiser. " 1\s soc i!J. tl. on of ·rwo .Sneci es of Gqrdinal fishe~ ,w"ith :lea Ane·,:orn?.-:; ~, '-"' 1.1 • r1'>=1. r i ~e ':) c 1 • 23(3) 521 -5? 4 • Qq.l1l, ·\ . L. " Voniterj :r.g Coral T~eefs f':>r • Sci. Jl(J) 544-551. 1981. En'.1P.an, R. "T·opul'=i.tion .SX:plosion of '.~canthresteY c'.is8oCi'ci.tf;d DestuctioYl nf herr;n.typic Corals West J' ·-"3.cific HP,gion." Hiolo,;i;y ~rr.1-Geolo,_::r:v of • Vol. J. 3d. J·ones ;~ndean, H. "i\cantrv:ist er rreat Barr" 0 · ·n -::.ef',r. ~L'-.L• ,.;.l . _ 185-191. 1977 '')lnnc:i_ :~.i.nd i ~1 the Indot~o::cs.l. Hee.f's . :J.nd Endea:n. 1976• wlanci Infestations ' D·roc • Tl..., i I'd T "'t r--r e -. !1 ."---..1.. 1 i . .1....,, e ~--• of Reefs of the ror·:~ l T-;)ee-r .·, '.... y ·rio, ~.,.:.._ ~...) .. • . • Glynn, P. W. 11 ..'.\s pect::1 of the Scology of Coral Hee.f~:J in the Western Atlantic Re~ion. u Btolo&'.'f a nd Geolo ~~ ·.; of Cora l Heefs. Vol. 2. Eds•.Jones a nd E;id~an. 1976. Glynn, P. W. "Interactions Betwee~ Acanthaster ~nd Hvmenocera in the Pield. · :.~1d Laboratory.," ? r oe : Third I nter. Cora.l ~1.eef SymJ2 . • 1977 • Goreau, T• .?. , n. L. Gareau, ·.; nd .'\utotroDhs ::..yr het erotrophs?" • Gr1. 'i s1 e, J • F. 0V·~_r·t ~ty :i.n Cor'1l GeoloP.:v of Co r u.l HP,efs. Vol. j_n the -le s t Indies." 197 3• r~7rban frr:>::.ct ." Bull. i·i J"e~sey: ?:rnt 1c-lhJ. l I nc • l 977, 197:-2 • • 17'-/ • dJm ~8.rtsP:, J. C,, 1977~Proc: 1fhird Inter. Cor.11 Heef 3vno. Een'.'ller, K. 1.977. ?roe: ;rhlrd I •:'lter. Coral Heef S:vno. • Jo"h' S •· o.;~ ., and R. l.::ndea;.'1. Bio1or;:y o·:i..nd Geolog:v :) f Co!'~j.l ::i.eefs. Vo1.4: Geolog·y 2. N. Y. , ~):~n fi'rg_:r.ls i s co, Londonl \.c :1.dernj_c ?ress , 1977,, l\.·1.ufr.i ~1n, . L. 1977. :;.)roe: rhird Inter. Coral deef 3 '.rrnp. 1• Knowlton, N., et a 1" " ~~videnee for Ihla.y ed Hortdlity in Hurr i carn::;)a.2·i a r(err J ana.icnn ~~Rp;hprn Co:r·:i.l~'.3." N~ture. Vol. 294,, Nov, 1981. Lanp· , J. "Intersnecj_fi c .:\F~ c;res s ion O.f Scleac tinian Corals .. 11 3u11. Vr~ l"' ; '1::-. "0i "')3(2) '=>60 ?,...,(C' 1 n f' Sp:;:).. ~e and F'oo•1 Hesourc~es ." ?roe. Third ~nter. CoralHe~_f.o 1977., • 1 P'ltten .! .. K. "rtn:i.n::iJ. AC)SOCiFl tes of Li"'.ring Heef c()r a1s. II Biology -1.nd Geolo&:7 of Coral. ~1eefs. \!o1 . J. ,~els . Jone s ~:i. :-13. Ende::rn. 1.976. Heese, E.S. "Goevolution of Cor J.ls :F1d ?lshes." ~-)roe. Third Inter, Coral Reef~ Symo. 1977. • Boessler, c. "Cuttlef ish& bor!': on fa Co~r·.s-tl Bed~ Ocean3. Vol. 14(4). 1981. Sura.ich , James L. :\ n Introduction to the Biolo ., of 1•19.rine Life. :rJubvque, Iowa: '.{rJ . C. Brown 197 ' 19.30. • ~h..;:-1 ::~t, FPtP.r K, 1'The Effect ct' .seawater Galct ur1 Concentra t1ons on Cora.ls" , Jo1Jrnal of Sedime·~1t·~r71 J?etrology, Vol. 49. ifo . J. 1. 97 9. i)1.ens " :derold. ~~. \ t oll gnvlroment. a~d ~:co1o;z:y . ~.rP~'i dn. -rrr~Yl ~r:d Lo~j_oru Y~1 l A Uni v r.; rsi. t • r ~.-r 8 ~:; s , 1962 ~ • • • /7S 8. Rifts Kevin Kelly, Nirmal Shah • I. Introduction I I. Geology A. MOR Surface Forms • B. Hydrothermal Activity I I I. Biology A. History B. Hydrothermal Vents C. Growth Rates • D. Adaptations E. Ecosystem Zonation F. Reproduction IV. Conclusions • V. Bibliography • • • • • • 17~ • • 8. RIFTS Kevin Kelly, Nirmal Shah INTRODUCTION Several kilometers below the Atlantic Ocean is the world's largest mountain range, the Mid-Atlantic Ridge. • This is the most convoluted part of the massive Mid-Oceanic Ridge system. Here are found some of the major accretion The African Plate and the American centers of the world. • Plate converge at the Mid-Atlantic Ridge. The plates are separating at a rate of several centimeters a year. Right along the crest of th~ Ridge, a huge rift-valley marks the • area of separation. This paper is concerned with the study of the geology and biology of this great rift-valley. In 1972 under the auspices of the National Academy of Sciences, • international scientists met to formulate plans to study the rift valley. In May 1975 a project named FAMOUS--an acronym for French-American Mid-Ocean Undersea Study--was set into • motion to study the area between 36° and 37° N. This lasted three years. In October 1977 geologists descended to the Galapagos Rift located approximately 330 kilometers northeast of the Galapagos Islands. The discovery of dense aggrega tions of biological life led to another expedition in 1 • 177 2 • January 1979 and different dives in the East-Pacific Rise at 21° North. The discovery of hydrothermal vents, the methods of undersea lava formation, circulation of sea• water through lava cracks and the aggregation of unique fauna have led to major revisions in geological and biological theories. (10) (11) • GEOLOGY • Using present observations and accepted theory, VanAndel and Ballard (1979) postulated a sequence of events in the evolution of the Mid-Oceanic Ridge (MOR). (1) This• sequence (Fig. 1) begins with rapid extension and extensive intrusion of sheeted dikes in a wide depression above a shallow magma chamber (t0 ). Evidence for this shallow magma• chamber comes from crystal to glass ratio studies and siesmic anomalies. Sheet flows issue from vent zones subparallel to the strike of the axial zone, concealing evidence• of earlier extension. This zone of rapid extension sub sides rapidly along boundary faults producing an appreciable thickness on the order of several hundred meters. The axial• volcanic ridge to the north masks the boundary fault zone with its pillow basalt aprons. On the south lies a marginal highwhichmaintains its position as the depression subsides . • • 17~ • • • • • • • • Fig. 1 At time rapid extension has ceased as the roof of t1 the magma chamber thickened, due greatly to the accumulation of sheet flows. Volcanic activity is now limited to a slow buildup of pillowed volcanoes. Modest subsidence occurs and some extension continues to give rise to fissuring, hydrothermal activity and the formation of warm springs. A new zone of rapid extension begins to form to the north of the axial ridge. The northern and southern marginal highs undergo isostatic uplift as a result of the thickening process taking place in the roof of the magma chamber. • 4 • At time t 2 the buildup of the axial ridge is nearly complete and ranges in width from 1 to 2 kilometers. The northern sheet flow depression has widened,and its southern • boundary fault is masked with pillow flows from the volcanic ridge. Finally (t3), the former axial ridge has become extinct • and is part of the southern marginal high, rising rapidly in response to isostatic uplift. The former southern mar. ginal high is now the south wall. Rapid extension is pro• ceeding in the sheet flow depression north of the former axis. The northern marginal high is stable while the sheet flow depression is subsiding rapidly.• The cycle ends with a period of pillow flows forming an axial volcanic ridge on which extensive fissuring produces the opportunity for hydrothermal circulation. This • occurs when the crust has become too thick over the magma chamber and it is easier for rifting to shift to a new zone of rapid extension. Given the magnetic age of the walls, • glass devitrification analysis and variations in sediment cover, (2) a complete cycle must last on the order of 10,000 • years . MOR SURFACE FORMS The principal types of surface forms along the MOR has• long been known as pillow basalts. Studies in the Cayman • /'Zo • 5 Trough, East Pacific Rise and Galapagos Rift valley have • shown that sheet flows are also an important component, especially on ridges with intermediate and fast opening rates. ( 3) Widespread sheet flows flank the axial volcanic I ridge and cover a large part of the valley floor (Fig. 2). • o· t~--J ...".,,....,,.........,...., 0 " , .. • • , , ~~ , . ,,..,. , ... I ·--· ; ""~ti C!lJOC tnt shrtl flow~(?) _ -Hockiy , onc!/o, 1umhled 'ht.er l1ows I [ ' Pillow flm111is [ J Yo~,,.,qe<£1 stitt>t flows ·~·'°'.'·] r.·.':~.. A>1ol rod~e ond •cared by conlcu•' '" lalhoms [ .• ·--Cl~~e-;1~ '.~~,·~-:~~;:~. ·----_.t:J ~'.~:<~'.·'"~':' .' '.'::.'~.--. -8f;;oir '~;i~;,:elo; --· ;,;;;01, _ _J .Fi)'.. 2. \'.,··dur.il· map,,( tht• C;il .q,.1)',1' "' i !It v.dlt·y .Jt Rt/\: sir.p lified fr <11n v:in /\nd•·l .m.i B.tl 1.Jrd ( 1979) (r.c,• lt1 r d1.-•t.:Jils l.Hl d;lt.:l, cnns l t uct i o 11 1 ~rnd :q..;t.• Jett•rndn.1t io11). Pillo._: l:asalt \.mit i..11 c ludt.."' ~; agl' r;mf:<· .,: hnrh s!ic·"~ t flow units, b;1t pill~)W~ cle:1r ly .1:-.:»' l,:i.1 tt·d in af.l"' and "1rigin with ynun)!e~t shi.'et ftm.. ·s arc. dh:-own St..'JH1r.1tc:1y. !bci<.ly ·11Hf j 111nhl\•\I !dH. ·t'L fb1\J:-; .11·\.' C'Om1,i ned fn s in)~l 1..· p.,ttern heca11~.;c of comn•,• n unccr t."'1 in ty i 11 :.l''.'.f l"~:.1Lin~ lhPS"' l)'pt:s. ~tinor ;~ r1...·., s ,,f h.J e~ly flu\t.' S i_n collapse pit~ have hcen o;dt tPd. ll ..... .Jvy Lr.1.<'k lines an· pruf lles of Fi;:urc J. Contnur~ on ;ax.i.:11 vo l c;rn i c t id t~•· (i11 :'1t l1oms; l f:itlh'tn ,·quals 1 .ll i::) ;1ft<·t V;u r e 1) . Fig. 2. From Hawaiian analogs it is seen that sheet flows can be considered a submarine equivalent of surface-fed pahoehoe. The difference between the two is recognized in the varying degrees of channelization and rates of delivery of lava to the flow fronts, which is directly associated • /Zf 6 • with differences in the duration and rate of eruption. (4) Sheet flows represent, early, brief but voluminous eruptions. (5) These are followed by more sustained, slower • but steadier eruptive phases that produce pillow basalts after an interval plumbing system has been established for the transport of magma through the thick sheet flow • complex. Therefore, pillowed volcanics should overlie sheet flow complexes of only a slightly older age. Other common features on the MOR are the collapse • pits. These occur in any area active volcanism and appear to result from subsidence of the lava in a crustal tube or sheet flow as a consequency of forward spreading of the flow • and/or headward drawback of lava into the subsurface plumbing. This produces a chamber in the hollow tube which is preserved when seawater invades the void. These hollow • tubes or sheet flows vary greatly in size and are only recognized when they collapse (Fig. 3) . • • • Fig. 3 • • 7 Lava pillars are numerous collapse pits, and current • evidence suggests that they are most likely produced by water trapped below an advancing flow. This water rises through the lava to the surface quenching a pillar of • basalt. (6) HYDROTHERMAL ACTIVITY The first evidence of extensive hydrothermal activity at the ridge axes came from the discovery of metal rich sediments overlying the young crust on the East Pacific • Rise. (7) In the Galapagos Rift the entire valley floor is dissected by numerous fissures ranging in width from hairline cracks to small grabbens several meters wide and equally deep. (8) Commonly fissures at the base of fault scatps show displacement exceeding 20 meters. The fissures occur in bundles or swarms and, for some reason, are mainly • (1) Only 10% of the observed restricted to pillow terrain. The most dense fissure fissures occur in sheet flows. swarms in the axial region occur in the oldest volcanics and • propogate towards younger pillowed areas where fissuring is just originating. It is through these fissures that hydro thermal water circulates. Independent confirmation of the interaction of sea water and crustal materials at high temperatures and to great depths has been determined by investigations of the • l'i3 8 • oxygen isotope systematics of basaltic rocks from the sea floor. Measurements of the isotopic composition of "unaltered" primary minerals and of the fractionation of • secondary minerals gave estimated temperatures of 300° C and penetration depths (a function of pressure) of more than 5 kilometers. (9) • High temperatures and sea-floor pressures demonstrate that the magma fluid compositions are profoundly influenced by sea water circulation. The effect of ridge-crest hydro• thermal activity on the major ion chemistry of the ocean and the ultimate composition of the oceanic crust is currently underestimated. (7) There is the prospect, • therefore, that the composition of sea water is subject to substantial volcanogenic control. The composition and temperature of hydrothermal fluids '• approaching the sea floor may largely be a function of spreading rate. Relatively slow spreading rates are characterized by intense tectonic activity, increased per• meability of the ridge-crest areas and hence, extensive seawater circulation and .low exit temperatures. High ratios of crystal to glass in the basalt in these areas • would lower sea water reactivity with the result being low-temperature hydrothermal springs containing low amounts of dissolved minerals. Conversely, relatively fast • spreading rates are characterized by less intense tectonic • ISL/ : • 9 activity and shallow magma chambers, resulting in less • extensive seawater circulation and higher exit temperatures. Lower ratios of crystal to glass would enhance the extent of reaction between seawater and basalt. In fast spreading • areas, therefore, high temperature with high concentrations of dissolved minerals, especially sulfur are likely to be found. (2) The hydrothermal springs are located near the present volcanic axis and usually on a pillowed slope near the contact with a young sheet flow. (3) Although the pillow • flows in spring areas are usually fissured, the springs themselves are not located on large fissures. Five active hydrothermal springs in the Galapagos Rift have been located • in the crestal area and Alvin observations suggest two inactive springs in the older marginal terrain, illustrating the fact that the springs are only active through a short • period of the MOR spreading cycle. These are some of the same hydrothermal vents where the colonies of exotic benthic animals and bacteria flourish in their isolated • ecosystem and are nourished by the internal earth. BIOLOGY HISTORY Green plants and blue-green algae are able to harness • • sunlight to synthesize energy-rich organic molecules from inorganic precursors. Ultimately all life depends on photosynthesis. Green plants typically form the base of • all food pyramids. This is true for land as well as the ocean. For many years the deep ocean, where little or no light penetrates, was thought to be lifeless. The great • naturalist Edward Forbes, 1815-1854, divided the sea into specific depth zones. As one approaches the abyss of the ocean,he thought, only a few sparks of life, if any, remain . • Over the years it was assumed that whatever life existed at the bottom survived on a rain of detritus from above. This sparse food supply would preclude a high biomass . • Thus the equation favored was: Biomass decreases rapidly with increasing depth, and the metabolic rates are lower than those of shallow species. le HYDROTHERMAL VENTS The discovery of dense animal life at vents near the • Galapagos spreading zone and at 21° N has led to a major re-evaluation of scientific concepts of productivity and growth in the depths. Sedimentation of organic debris • from the euphotic zone is not large enough to account for the biomass present at the vents. Early on it was suggested that these communities depend on alternative food sources . • This is supported by the dichotomy found between the stable • 11 /8(o • • • • • • • • • carbon isotope ratios of vent and non-vent organisms. It 13 was found that the c values of vent clams, mussels and worms were lower than those of other deep-sea organisms. It was concluded that this low 13c resulted from the utilization of food unlike that found in the euphotic zone. (12) (13) Collection and analysis of bacterial mats from around the vent sites have shown that autotrophic microbial productivity is the basis of the food chain. Certain chemoautotrophic bacteria preferentially fix 12 Co2 to a greater extent than photoautotrophs thus producing lower 13c values. (14) The energy and reducing power needed for carbon fixation is thought to be generated by the oxidation of sulphur compounds such as hydrogen sulfide which is dissolved in high concentrations in the vent 105 waters. The large bacterial biomass--5 x ml-l --is concentrated in clumps in the water and arOi.md the vent. These bacteria are capable of producing useful energy in the form of ATP from sulphur compounds. Extremely high concentrations of ATP were detected in vent samples. (16) It was estimated that there was approximately 100 to 250 /ug of cell carbon per liter of water. By comparison most deep sea environments contain less than 1-2 /ug of organic carbon. A GTP:ATP ratio for microbial corcununities at the vents was found to be comparable to those reported from intertidal flats--0.16 ± 0.08 to 0.17 ± 0.09. GTP:ATP • 187 • ratio is an index of cell biosynthesis . • This particulate matter should form an excellent food base for filter and suspension feeders. In fact unique animals have been discovered: Galalheid crabs, • clams, mussels, polychaete worms and others yet to be identified. These are filter-feeders. Predators such as the Brachyurian crabs scavenge around the base of worm • I colonies for food. Both these methods of feeding seem quite improbable in the case of the vestimentferan worm Riftia Pachylila Jones. This worm lacks a definite mouth, gut and anus. It has been found that the trophosome tissue of the worm is spotted with prokaryotic cells. These are • possible chemoautotrophic symbionts similar to the gram negative bacteria found in the vent waters. (16) High activities of enzymes used in generating ATP • from the oxidation of sulphur compounds, i.e. thiosulphate sulfurtransferase (rhodanese), APS reductase and ATP sul phurylase, were found in the trophosome tissue of the worm• • In addition, high activities of .RuBP Carboxylase and ribulase 5 phosphate Kenase, which are enzymes of the Calvin Benson cycle of Co2 fixation were also found. Since the bacteria • make up the major part of the trophosome tissue, it has been suggested that they are capable of generating ATP by way of sulphide oxidation and reducing co2 to organic matter . • This then is a possible mechanism for autotrophic nutrition• • • 13 • • • • • • • • • • GROWTH RATES Growth rates at these sites are very rapid. Analysis of serial incremental growth layers in the shells of freshly collected live clams of the species Calytogena Magnifica and mussels of unknown species have revealed the highest growth rates documented for deep-sea species. The largest clam specimen was 22.6 cm long. The growth rate was estimated to be 5 cm per year for the first 6 cm and about 2 to 3 cm for the next 2 cm, with an average growth rate of about 4 cm per year. The age was estimated to be about four years old. (17) Mussels ranging from 1.5 to 18.4 cm were collected. Growth rate was estimated to be 1 cm per year. Populations are less than 19 ± 7 years old. (18) Both these bivalves have ontogenic growth curves similar to shallow-water bivalves. On the other hand, growth rate of a deep-sea clam Tindaria Calistiformis determined to be 0.0084 cm per year, with a life span of 100 years, is much slower. The Galapagos Rift clam and mussel have yearly growth rates 500 and 120 times faster. ADAPTATIONS These organisms have unique adaptations to the hostile environment in which they live. The adaptation that has been most studied is the functional characteris tic of the blood. Data has been presented to indicate • 14 • that the hemocyannin of the Brachyruan crab and Diftia Pachyptila have oxygenation characteristics that are suit able for life in a heterogenous environment. Hemocyanin • in the whole blood has relatively high oxygen affinity • (Crab: P 50 = 6.6 mm of mercury at 2.6° c pH 7.5. Worm: P50 = 1.8 mm of mercury at 3° C.) and relatively independent of temperature over the range of 2° to 30° c. In the worm carbon dioxide has a small effect on oxygen affinity. The crab blood has separate sensitivities • to co2 and pH. It has low pH affinity and high Co2 affinity. Separation of the effects of co2 and pH on affinity may be useful for the crab which is active but • also undergoes anaerobiosis. The low pH sensitivity would give the blood oxygenation properties that are rela tively constant across the wide range of temperatures in • the vent area. The high oxygen carrying capacity would allow both species to rely on stored oxygen reserves during periods • of low oxygen. It may also reflect a high demand for oxygen for H2s metabolism in the case of the worm. (19) (20) • ECOSYSTEM ZONATION The vent ecosystem is in many cases clearly zonated. At the Galapagos Rift fanciful names have been given to • "oases" with unique fauna. Clambake I and Clambake II are • 190 15 areas where the clams proliferate. The Dandelion Patch has a large population of the siphomophore dubbed "Dandelion." The mussels dominate the Oyster Bed. The Garden of Eden is characterized by Riftia Pachyptila. It has been suggested that the species of larvae that arrive first at a vent site will come to dominate. This hypothesis is known as the Founder Principle. REPRODUCTION The animals undoubtedly produce larvae. These larvae have to be "long distance" organisms capable of remaining in the plankton for long periods. They may even be able to postpone their metamorphosis for days. (21) Riftia Pachyptila has separate sexes. There is a single external difference between males and females, i.e. paired anterior ciliated grooves and ridges associated with the genital apertures of the males. These are lacking in are located in the female genital aperture. females. Eggs Sperm have elongate corkscrew-shaped bodies. (22) CONCLUSIONS The above text is composed of the most elementary ridge system and the secrets observations of the mid-oceanic to the life it holds. Clearly this information gives rise to more questions than it answers. Man, for the first time, • • • • • • • • t • 191 • has observed a large ecosystem whose basis for life is not • photosynthesis. We witness the origins of ore bodies and crust formation. The door is slowly creaking open to some of the most awesome processes of nature that five year s ago • were merely speculation. The future of the areas is uncertain. Large amounts of biomass from rift-zone conununities could be utilized by • man. In addition, recently discovered mineral deposits may bring about the political colonization of the world's oceans in light of their economic potential. As in all • processes of nature, man must take this time to explore all aspects of the process in question before wisely introducing himself to a specific problem. With continuing research and careful foresight the mid-ocean rift zone and the life associated with it will benefit mankind • • BIBLIOGRAPHY • 1. VanAndel, Tjeerd H., and R.D. Ballard, The Galapagos Rift at 86°W: Volcanism, Structure, and Evolution of the Rift Valley, Journal of Geophysical Research, Volume 84, Number B-10, 10 September 1979. • 2. Corliss, J.D. et al., Submarine Thermal Springs on the Galapagos Rift, Science, Volume 203, p. 1073-1083, 1979. 3. Ballard, Robert D., W.B. Bryan, J.R. Heirtzler, G.R. Keller, G.J. Moore, and Tj. H. VanAndel, Manned Submersible Observations in the FAMOUS Area, Science, Volume 190, p. 103-108, 1975 • • . / /92. • 17 4. Ballard, Robert D., and VanAndel, Tjeerd H., Morphology and e Tectonics of the Inner Rift Valley at Latitude 36°50'N on the Mid-Atlantic Ridge. Geologic Society of America Bulletin, 88, p. 507-530, 1977b. 5. Ballard, Robert D., Holcomb, Robin T., and VanAndel, Tjeerd H., The Galapagos Rift at 80°W: Sheet Flows, Collapse Pits e and Lava Lakes of the Rift Valley, Journal of Geophysical Research, Volume 84, Number B-10, 10 September 1979, p. 5407-5422. 6. Ballard, Robert D., and East Pacific Rise Study Group, Crustal Processes of the Mid Ocean Ridge, Science, e Volume 213, 3 July 1981. 7. Lonsdale, Peter, A Deep-Sea Hydrothermal Site on a Strike Slip Fault, Macmilliam Journals Ltd., 1979. 8. Ballard, Robert D., and Moore, James G., Photographic Atlas of the Mid-Atlantic Ridge Rift Valley, Copyright 1977, • Springer-Verlay, New York, NY. 9. Crane, K., and R.D. Ballard, The Galapagos Rift at 86°W: Geology of the Hydrothermal Springs, Journal of Geophysical Research, Volume 84, 1979. • 10. Enright, J.T., et al., Nature 289: 219-221. 11. Corliss, J.D., et al., Science 203, 1979. 12. Rau, G.H., and Hedges, J., Science 203: 648, 1979. • 13. Rau, G.H., Science 213, 1981. 14. Degers, E.T., et al., Deep Sea Res 15, 1978. 15. Karl, D.M., et al., Science 207, 1980. • 16. Cavanaugh, et al., Science 213, 1981. 17. Turekian, K.K. and Cochran, J.K., Science 214: 20, 1981. 18. Rhoads, D.C., et al., Science 214: 20, 1981. • 19. Arp, A.J., and Childress, J.J., Science 213: 17, 1981. 20. Arp, A.J., and Childress, J.J., Science, 1981. 21. Lulz, R.A., et al., American Zoology 19, 1977. • • • • 22. Joves, M., Science 213: 17, 1981. • 23. Allmendinger, Richard W., and Riis, Fridtjof, The Galapagos Rift at 86°W: Regional Morphiological and Structural Analysis, Journal of Geophysical Research, Number B-10, September 10, 1979, p. 5379-5389 . 24. Ocean Science News, John R. Botzum, editor, Volume 23, Number 37, 21 September 1981 . • • • • • • • ,. 19'-/ • • • • • • • • • • • JORGE ALBERTO GONI 9. TITLE: PLANKTON OF THE SHELF I. Introduction. II. Physiological Ecology A. Chemical Composition of Sea Water B. Physico-Chemical Parameters and Their Implications 1. Light 2. Temperature 3. Nutrients III. Population Ecology A. Characteristics of Plankton 1. Population Growth 2. Behavioral Factors (a). Size (b). Shape and Orientation (c). Cell Density 3. Cyclic Populations (Succession) 4. Diversity B. Main Interactions in Plankton Populations 1. Predation 2. Competition IV. Energy Flow A. Energy and Complexity of Planktonic Environments B. Geographical Distribution of Productivity. V. Prospectus. I '15 • • 9. PLANKTON OF THE SHELF JORGE ALBERTO GONI • INTRODUCTION The ocean basins usually have a narrow margin, or shelf region, surroun ding the land masses and extending seaward a variable distance from almost nothing off Miami, Florida, to over 800 km north of Siberia in the Artie ocean. The continental shelves are also defined like an underwater extension of the continent • which account to nearly one-sixth of the earth's total land area • All the water that lies over the continental shelf, it is named as the neritic pelagic region. This area includes the most productive part of the oceans because it is close to rich supplies of nutrients from land as well as • from upwelling of deeper nutrient-rich water • PHYSICO-CHEMICAL PARAMETERS AND THEIR IMPLICATIONS. • Composition of Sea Water. On the average, seawat~r is composed of 96.52% water and 3.49% dissolved substances, mostly salts. However, this concentration of salt may be altered in neritic water, since the influx of freshwater from rivers, and • direct precipitation on this area, although the final change in salt concentration can be in the order of 0.1-0.2% depending on the geographical location of the area. Table 1 represents all the elements found in seawater, and their respective proportions • LIGHT The suns' electromagnetic energy is selectively absorbed and scattered • as it penetrates the uper layers of the sea in processes that are strongly wavelength dependent • Infrared and visible red light () 780nu) are abosorbed by the water itself • in the first half meter, reducing the solar energy available to one half. Attenuation of light yellow light with blue and blue-green light (max. about 480 nu) penetrating the farthest-to about 200 m. in the clearest oceanic waters Coastal waters and upwelling regions have modified optical properties due to increased concentrations of phytoplankton, and suspended particles of inorganic or organic origin. • To survive successfully i n these light-limited marine habitats, the algae must be adapted to utilizing particular wavelenghts of the full visible spectrum• • Iqlo TABLE 1 • Comparative Values of Elements in the Environment* Seawater Earth Crust Marine Organisms Land Organisms Element Ran9:e (m9:/l) Average .ca. 0 • .9 c.§ c L. ~c 0C .-C 0 -c ·~ o>< U-> u • .c u ·~ .c a. (L 0 1·0 ti: c't ~) 0·8 u:c 0·6 0·4 E 0·2 c ~ • (4) '::' Q,0 u I 0·1 0c I -0·08 ii. I 0 ·06 1 0 • I ( 3) ..0"' I --0·04 0 I Cl.) I 0 I > (2) : I 0·02 I •II _ _,___.__ ______J.I ___ __.____~ •100 500 oOO 700 Wavelength (nm) Fig. 3.2. The ahsorption of light hy different algal pigments and the ·windows or clarity· in wal\.:r absorption. The s1wctra for the pigments approximate fo those 1111.:asun.:d i11 riro. For the sakl: of this illustration. fucoxanthin and rt:ridinin ahsorrtion arc considered identical. • 199 • • process. From Table 1, it can be observed that nitrates, phosphates some other elements tend to be in short supply in surface waters, where they are • taken up by phytoplankton. A certain amount of the nutrients may be regenerated and recycled within the euphotic zone, but in deep waters they tend to accumulate as as result of release and lack of functional photosynthetic organisms (Figs. N-33 and N-34). The greater productivity of coastal areas compared with • deep water is partly a consequence of more rapid recycling of nutrients where the sea bottom is closer to the productive layer. However, in areas where the process of recycling is slow, for instance, in tropical waters, it is observed a continuous growth of plankton even when analytical procedures indicate lack • of nutrients. A common observation from many studies is that near maximum growth rates (r max) of marine phytoplankton can be sustained when ambient limiting nutrient concentrations are below detectable concentrations and biomass levels are exceedingly low. These conditions are typical features of surface coastal waters during summer periods. • The problem is compounded further because phytoplankton have an enormous capacity to exploit efficiently micropatches of nutrients that may be available from plankton excretions and bacterial mineralization of organic matter (Goldman and McCarthy; 1979). • Such an adaptive feature must indicate an evolutinary response to life in a highly transient environment. In this case, organisms with more efficient systems of uptake of nutrient, are in an advantageous position to occupy the • habitat. ECOLOGY The frequency and magnitude of fluctuations in natural populations depend both on the variability of the environment and the life span of the • individuals in the population. Short-lived organisms are more sensitive to short-term fluctuations in the environment and their populations can fluctuate dramatically. The lifespan of the single-celled algae that constitute the phytoplankton is measured in short periods of time, generally in days; the turnover rate of algal populations isttherefore extremely rapid, making the populations vulnerable to the vagaries of short-term environmental fluctuations • • • • 0 ...... '~ ' ' • ' ' ' I 1000 I I \ I I I 1-\tlantic---/ I I I I Indian--I I I • E I 1 -Pac i fic -5 2000 I I 1 ::I. \ I . 1 ,• - ' ' (a) "-!!-~ ...,.... "f... , .... "'1" · ' .. n· "T >1 i1' T 1 ..... "1 'f r : TT°' , (b) (c) ' '· '" _[qL.___ • • I ~08 • • • • • • • competition, even if equilibrium ocurred. In other words, low specific competition coefficients characterize phytoplankton species. However, this idea does not explain the high dominance of some species during certain conditions like input of nutrients, or climatic changes. A personal point of view, it is that this phenomenum may be explained in terms of evolved physiological adaptations to both, physico-chemical and biological parameters, which combined result in low overlap of functional niches occupied by plankters. ENERGY FLOW A. ENERGY AND COMPLEXITY OF PLANKTONIC ENVIRONMENTS. Coastal environments are dynamic in nature and have energy flowing through them. As it is known, light is the source of energy for marine environments since once captured by phytoplankton, this energy fixed is continually cycled through food webs in marine systems. Thus, as any cormnunity, planktonic eco systems posses a trophic structure, rates of energy fixation and flow, efficiencies, diversities, distributions and successional stages. Under relatively stable conditions, an ecosystem will tend to evolve toward the most efficient use of the energy captured by primary producers. This can be done by diversification and speciali~ation of biological components. The ratio between the total energy captured by primary producers and the total biomass in an ecosystem is an index of the maturity and stability of the ecosystem. When this criterium is used to analyze coastal environments, the results indicate a high productivity and also fast rates of flow of energy in certain periods of the year, or certain restricted areas. These results are due to the constant input of energy in coastal areas, which cause a reduction in maturity, then driving the ecosystem into a younger more productive stage. This can be related with the points discussed in succession, since successional stages through the year represent the degree of maturity of the system, where the climax is reached during short periods of time; and then disrupted by cyclic inputs of energy. B. GEOGRAPHICAL DISTRIBUTION OF PRODUCTIVITY. Differences in the fertility of the marine environment in several localities, and at different times, depend upon the availability of plant nutrients in the surface layers. Certain areas are of consistently high fertility, for instance, upwelling • coastal areas; and others are ocean deserts (pelagic areas), and in many regions the fertility fluctuates seasonally. As we can observe, the areas of good productivity include most of the seas overlying wide continental shelves. • There are several reasons why this shallow water is relatively rich in nutrients. Waves erode the coastline and stir up the sediments, releasing nutrients into the water. Fresh water running of the land may carry additional • nutrients, including trace elements such as iron, copper and managanese which are often scarce in deep water due to precipitation. Where there are centers of human population, sewage i IB usually poured into the sea and provides nutrients after decomposition • In temperate areas, the surface layers are well provided with nutrients by convection during the winter and early spring, but the supply of nutrients diminishes during the summer when the formation of a thermocline prevents reple• nishment by vertical mixing. Poor productivity occurs where vertical mixing is minimal. Throughout the tropics~ wherever a permanent thermocline is present, production rates are mainly low despite rapid regeneration. However, because production continues through the year without much seasonal decline, it is pro• bable that the total annual production in most tropical areas substantially exceeds that of temperate seas. For example, in the Mediterranean, fertility is low because nutrients are continually lost in the deep outflow which forms the bottom current through the Strait of Gibraltar. The inflowing surface current • is derived from surface levels of the Atlantic which are relatively poor in nutrients. However, this pattern can be modified in the following · years, mainly because the constant introduction of nutrients by sewage provenient of human population nucleus, localized all long the Mediterranean Coast. • PROSPECTUS A great deal of research (on marine environment) has been done in the last decades. This must be mentioned because when we try to analyze the structure of the marine ecosystem, including its relationships with other systems, we • conclude that man's role has been exclusively predation. Since there is not alternative for other function, it is my opinion that scientific knowledge must be applied to decide which ecological balance is most desirable for man and to balance the conflict between food requirements and environment's quality. As was • mentioned in the part about productivity, an adequate organization and structuration may change the negative effect of sewage over the environment, in positive • ~lo • • • • • • • • • information when applied to the adequate ecosystems. This is only an example of the many alternative existing for the solution of the frequently mentioned problem of pollution of the marine environment. The range of alternatives it will be expanded, as the knowledge of the marine environment be expanded too. ~II BIBLIOGRAPHY I• I I I • 1. Bayley, S.T.; Morton, R.A. "Biochemical Evolution of Halobacteria", from "Strategies of Microbial Life in Extreme Environments" ed. M. Shilo pp. 109-124. Berlin: Dahlem Konferenzen, 1979 • • 2. Tait, R.V. Elements of Marine Ecology. 3rd ed. Ed. Butterworths, London, 1981, 356 P• • 3. Brock, Thomas D. "Principles of Microbial Ecology" Ed. Prentice-Hall, 1966, 306 p • 4. Kinne, O. 1970 Marine Ecology. Environmental Factors part 1. Vol. 1. Wiley-Interscience. 681 p. 5. Oppenheimer, C.H. 1970. Bacteria, Fungi and Blue-green Algae. In Marine • Ecology, O. Kinne (editor), Env. Factors. Part 1, Vol. 1. Wiley-Interscience. 681 p. • 6~ Morris, I. 1980. The Physiological Ecology of Phytoplankton. Studies in Ecology vol. 7. University of California Press. 626 pp • 7. Ricklefs, R.E. 1974. Ecology. 3rd. ed. Chiron Press, Newton Massachusets. 848 p. 8. Mitchel, R. 1971. Water Pollution Microbiology. Wiley-Interscience. 848 p • • 9. Edmonson, W.T. 1966. Marine Biology. Vol. 3 Ecology of Invertebrates. New York Academy of Sciences. 313 p. • 10. Blumer, M.; Souza, G. and Sass, H. Marine Biology, 5, 195 (1970) • 11. M. Blumer, Oceanus 15 (2), 2 (1969). 12. M. Blumer, in Oil on the Sea (D.P. Hoult, Ed.), Plenum, 1969. • 13. D. Framer, A.F. Carlucci and P.V. Scarpino, in Marine Microbiology (C.H • Oppenheimer, Ed.) Thomas, Springfield Illinois. 1963. 14. Lewis, W.M., 1980. Zooplankton Community Analysis. Springer-Verlag. New York. 163 p. I I • • • 10. Plankton of the Open Ocean Jeff Dillaha, Ann M. Seman • I. Physical/Meteorological II. Density/Buoyancy III. Water Movements • IV. Primary Product i vity V. Phytoplankton A. Dinoflagellates • VI. Viruses VII. Yeasts VI I I. Fungi • IX. Bacteria X. Algae XI. Zooplankton • XI I. Protozoa XI I I. Cnidaria XIV. Ctenophora • XV. Annelida/Chaetognatha XVI. Crustacea XVII. Mollusca • XIX. Tunicata XX. Transitory Larva XXI. Energy Cycles • XXII. Sulfur Cycle XXIII. Nitrogen Cycle XXTV. Rihliography • • 10. PLANKTON OF THE OPEN OCEAN Jeff Dillaha, Ann M. Seman • Plankton can be defined as the whole of those pelagic organisms which float and drift under the action of water movement. The plankton dealt within this report will be those organisms 1. • found in the open ocean, namely the ocean not enclosed by headlands. (For our purpose excluding both Arctic regions and the areas· over the continental shelf) The broad class of plankton includes the phytoplankton which ranges in size from two micrometers two millimeters, zooplankton and transitory zooplankton which can reach up to 50 micrometers in size. It is found in such a syst.arri that the community of these organisms in this particular area will interact with each other and the environment and its physical distinctions thereby forming what is · • known as an ecosystem. Physical/Meteorological • The physical and meteorological factors greatly effect the . plankton population and distribution. Due to the vastness oceans the main geographical areas dealt with are temperate, • tropical, and subtropical areas. The temperature ranges from -2°c to 4o0 c, salinity is 34°/oo to 37°/oo and the average ocean depth is 3,800 meters (12,500 feet). The actions of • carbonates and bicarbonates act as buffers to maintain the ph. between 6.5 and 8.3. The most important physical factor effecting phtoplankton • is the light penetration in the ocean. The amount of light penetration directly effects the photosynthesis of the phyto plankton. Seasonal and diural variations account for the • ~l'l -2 differences of penetration through time. The zone in which • th~s~ autotrophic phytoplankton can utilize light for energy is termed the euphotic zone. The depth at which light penetrates is 1% of the surface is called the compensation point, beyond • this point no appreciable photosynthesis takes place. Factors such as winds, currents, turbidity can also influence the depth of light penetration. (see figures \ 1 2 * 3 1 • The rate of photosynthetic activity is directly related to the amount of pigment available to the phytoplankton. The major pi~ment in the cells is chlorophyll, but other pigments also can t {• be used to transfer energy. The absorbtion of light by pigments i s de pendent on the wavelength of light penetrating the ocean at different depths (see fignre 4 ) . The products of photosynthesis • are oxygen and carbon compounds. Thus the phytoplankton are the primary producers of the oceanic ecosystem and constitutes the first trophic level. They are also one of the major producers • of oxygen in the world. The temperature of the oceans is relatively constant, except fluctuations due to season changes as well as depth. A temperature t gradient exists in the ocean which forms layers of differing temperatures and salinity. These layers can be formed by currents and the presence of a therocline, determining the types of species • present at different depths. Density/Buoyancy • The density of water is dependent on temperature and the total dissolved salts. (The higher temperature the lower the density and the more salt, the greater the density.) • -3-.:l../S• The density of the ocean water will effect the buoyancy of the plankton at different depths. Density also effects Lhe rate at which plankton move through the water column. The buoyancy • of plankton is directly related to surface to volume ratio. Various species have evolved different means of controlling buoyancy and movement. Many have various shapes or like the • diatom Ryizosohenia have radial projections called spicules. While others such as copopods having exoskeletons employ the use of gas vacuole, oil droplets or differing ion concentration to • control buoyancy. Also many species may use a combination of methods for this purpose. Furthermore, the products of photosysthesis by phytoplankton or grazing by zooplankton increase• their sinking rate. If the plankton sink out of the euphotic zone death may result. • Water Movements Water movement allows plankton migaration in the ocean water. Currents are a critical factor in determining plankton pacial • distribution. This distribution can be into an area of favorable or~unfavorable environmental conditions. Basically, su rface currents are directed by prevailing winds which form a pattern of• nearly closed loops which move clockwise in the northern hemisphere • and counter-clockwise in the southern hemisphere. Also deep water currents effect the distribution of plankton and can serve both as a barrier and a nutrient source. (see figure~) Cyclonic rings can trap plankton in an area of different temperatures which can • kill them. The oceanic thermocline can serve as a horizontal barrier to plankton's vertical movement in a water column. The plankton become caught in the upper layer of warmer wate~ and can • I -4 use up the available nutrients restricted in that layer. Plankton of the tropical waters are much smaller than those of the temperate zone due to the lower density of water. This is due to the presence of the thermocline. For this reason more skeletal extensions are • used to increase surface to volume ratios. Also the presence of deep water currents direct the distribution of plankton, serving both as a barrier and a nutrient source. • The phenonmenon of upwellings can also make nutrients available for plankton use. These upwellings occur due to coastal wind driven currents which are offshore winds that cause a drift of surface I water away from the shore. The warmer surface water is then replaced by colder nutrient rich water from below. The upwelling phenomenon is not limited to coastal areas, they can occur around ocean island t chains and sea mounds. Convection cells can also form indifferent parts of the ocean. They occur where heat loss at the surface creates an increase in density of the surface water. This causes the surface water to sink and to be replaced by the water below it. The upwellings, downwellings, convection cells and deep sea mounds serve to move I the water and thus the plankton found there. These water movements determine plankton migration and are essential for their survival. The overall plankton populations are greatly affected by I weather changes, especially the phytoplankton which are dependent upon the temperature changes occuring daily as well as season· ·~i1y. (see figure ~ ) t Primary Productivity Ocean primary productivity is defined as the product of phytopl ankton and other photosynthetic or chem0synthetic organisms • -5-~17 • found in the ocean. Data on primary productivity can be measured in various ways, such as chlorophyll, oxygen, or carbon content. Some errors arise due to smapling methods and the minute size of • plankton which only allow for estimates of production and standing crop populations. Primary productivity is usually expressed in milligrams or grams carbon/meter2/day when all levels of the water • column are incorporated into the calculations. (see figure+) As stated previously, productivity will vary greatly with the seasons and geographical areas. The seasonally variations for different • ocean masses are given in figure Many factors will limit the productivity of plankton in the ocean. For example, the multiplication of the phytoplankton algae • increases the absorbtion of light in the environment and, consequently limits the available energy for photosynthesis. Furthermore, light is absorbed not only by phytopla~kton pigments but by the water • itself, by dissolved colored substance, by detritus in suspension and by zooplankton. These factors can thus limit plankton production and also the number of plankton themselves . • Producitivity is related to the biomass, although it does not ! always correspond directly to it. Generally the measurable production is limited to the euphotic zone, while the biomass, determined by • the chlorophyll, may be traced to greater depths. In other words, the ratio between production and biomass expressed in the terms of carbon, the relative productivity, will show considerable variations • as a function of depth and season. The phyto plankton as the primary producers, first trophic level, are consumed by many organisms. Thus, their biomass can• determine overall fish production as well. Consequently, the greater the fertility of the water the greater its primary productivitv . • -6-~J~ • In addition, the productivity is tied to the number of trophic levels. The fewer the number of the trophic levels in the food chain, the more efficient the transfer between each pair of levels. Thus, in rich upwelling areas, fish like anchovies may feed directly • Consequently, on phytoplankton allowing a high ecological efficiency. clear ocean water contains multiple trophic levels causing the The most limiting • ecological efficiency to be low. (see figure~) factors of primary producitivty are the low availability of nitrogen and phosphorous. I Phytoplankton The open ocean supports a large variety of organisms which are able to either swim or float in the various water layers. These • Almost organisms range from the very large to the very minute. all marine life is sustained, in essence, by microscopic plants and r:ear microscopic herbivores and carnivores, i.e. plankton. Animals • such as copepods, medusae, and larvae of various organisms compose that group of plankton known as zooplankton. Some of these plankton contian chlorophyll which make photosynthes~s possible and thus they I More than 90% of all the basic organic are termed phytoplankton. material that feeds and supplies life in the sea is produced within the li~hted surface layers of the ocean by a variety of phytoplankton. e The most abundant from of phytoplankton are the diatoms. These organisms have been considered one of the most important marine They are capab~e of forming large blooms of plant e microorganisms. material. They remove large quantities of nutrient material such as phosphate, nitrogen, silica and cause rapid changes in carbon dioxidP content. This is an important factor in the stability and sustenance t • -7-o1 I<}• of other organisms . Diatoms also serve as indicators of water mass. They: are regarded as the chief food of plant-feeding fish, copepods • and other animals . • Diatoms are unicellular, non-motile and motile plants which can be characterized by the shape and structure of their siliceous exoskeleton (except in the genus Chaetoceros). They are important Their skeleton is the only part preserved in the geological record. They may occur singly (Ditylon, Coscinodiscus) in rock formations . • or in chains (Chaetoceros, Thalassiosira) . • These single-celled plant: skeletons are composed of two valves, the hypotheca and epitheca, each valve made up of pectin and a considerable amount of silica. The presence or absence of a raphe • slit in the valve, separates the diatoms into pennates and centric diatoms, respectj_vely. Out of this s1i t, pro};oplasm is extruded and serves as a pseudopod used primarily for movement. It has been suggested that these rod-like diatoms are usually benthic with the centric or circular being planktonic. (see figure\O) • Numerous chromatophores occur throughout the cell and may rearrange according to light intensity. These chromatophores contain a mixture of chlorophylls and several carotneoids producing • a visible brown color. Diatoms normally store oil or fatty acids as the end product of photosynthesis. The species Coscinodiscus found in the North Sea can produce so much oil that an oily patch or slick may be seen . on the suface of the water . • • The size of diatoms does not vary according to the species alone. Size can vary according to means of reproduction. Diatoms can mulitply very rapidly according to environmental factors such as light intensity, temperature, pH. Normally diatom blooms occur seasonally, with maximum production during the spring and autumn . • -8-~:2..0• Dinoflagellates The next major constituent of phytoplankton are the dinoflagellates. They are similar to diatoms in that Lhey also contain chromatophores, giving them a red or brown coloring. However, unlike diatoms, these • organisms possess the power of movement by the possession of at least one flagella, sometime two. This algae is divided into two sections I (the hypotheca and the epitheca) by a groove (the transverse furrow) One flagella is directed longitudinally and provides for the general directional movement whereas the other flagella circle I around the transverse furrow and causes the cell to rotate. (see figureH) Dinoflagellates belong chiefly to the photic zone of the ocean and occur inclose relation to the diatoms. The reaction between them I is primarily for nutrient exchange. They also provide a good food source for other animals such as copepods and fish. Diatoms and dinoflagellates occur in all waters. The ratio of diatoms to dino • flagellates varies depending upon the area of water, e.g.tropical waters dinoflagellates are more numerous than diatoms. Sometimes during the summer months, the flagellates collect in high concentrations and begin to shade one another from the light. Each cell struggles • to get closer to the light producing a high density of organsims and turning the ocean water to colors of red and brown. These "red •tides" can often become too great for their own survival and die off. Their debris is eaten by various organiHms and the remainder eventually settles to the ocean floor. This material can be highly toxic. Most of the toxic dinoflagellates are marine organins and generally • within a range of 40 to 60 micrometers in diameter. Blooms of this sort are usually depend upon the annual cycles of the environment. Only'exact production of temperature, salinity, illumination, pH and concentration of trace elements and nutrients . Most of the reported • -9-;u/• causes of shellfish poisoning, resulting in paralysis has been deter~ mined to be a dinoflagellate, particularly of the Gonyaulax and Gymnodinium genus . • Normally these organisms are airobic and produce energy by photosynthesis. Some speices, such as Chalamydomonas moewussi can photoreduce carbon dioxide. Dinoflagellates require nitrates • in the presence of light and ammonia or amino acids in the darker ocean layers as their source ·of nitrogen. The energy cycles of thes organisms as well as other shall be discussed later on in this report . • The flagellates may be unicellular as in Chlanydomonas or multi-cellular as in Volvox. They reproduce by fission. A common group of small phytoplankton are the Coccolithophores. They are • biflagellates with an external skeleton composed of calcareous rings or spines. They: are an important food source for other organisms in the tropical Atlantic and Indian oceans. They all contah • chlorophyll -and~ some swimming ability. · They often contain an oil droplet which is used for food storage and buoyancy . • Viruses Viruses inthe marine environment have been studied and reported by few authors. Phages have been found and reported which• cause plant and fish diseases. It has been noted that some phages have been active against marine bacteria. These viruses can be characterized from land viruses as they generally are inactivated • in an hour at 55°c whereas terrestrial phages are inactivated at 6o0c. They were also conditioned to a higher salinity environ ment higher divalent cation ratio and lower temperature . • Viruses in the marine environment have not been studied extensively and seen to have little impact on marine ec ology . • -10 Yeasts • Marine yeast studies like viruses, have been limited and their function in this environment unclear. It is believed that yeasts can be associated with fish spoilage, sea H29 and sediments. • Those yeasts that have been studied are morphologically yeasts. It is thought that they have a terrestrial origin and have merely adapted to a marine environment. The ability of yeasts to live • anaerobically would allow for them to live in the sediments. Yeast counts are generally higher in areas closer to seagrass and algal beds. They might prove to be an important • saprophytic origin in the decompensation of dying or dear origin matter as well as an improved food source for zooplankton. The most commonly found yeasts a~e Candida,Torulopsis, • jyrptococcus, Trichosporon, Saccharomyces, and Rhodotoula~ Occasionally blooms of yeast are found in discrete marine water e.g. areas of the North Sea. • Fungi Fungi organisms in marine ecosystem have generally been • overlooked. Some fungi species can be found in marine environment and form slime molds, e.g. Labyrinthula species and require sodium chloride. They are normally found in association with algae and plants .. Bacteria • Bacteria in the marine environment play the most important role of micro-organisms. They are the bulk of the organisms in the anaerobic zones of the ocean. As on land bacteria are • primarily responsible for restoring nutrients back into the ocean through degradation and utilization of decaying organic material. They are also responsible to some extent, of turning solar energy • • -11into biological energy. Bacteria can convert and translocate minerals, as in the production of coal and petroleum. They can also transform • organic material to inorganic, and vice-versa. They can alter the physical properties of the environment, such as pH and Eh. They can assist in the attachment of animal larvae in the littoral and • • sub-littoral zones. Bacteria are recognized in the formation of sedimentary sulfur deposits, and ore . Marine bacteria~ can be found in all areas of ocean temperature, salinity, and depths. All marine bacteria are found to be halophilic, and will not grow in the absence of NaCl. The ions • found in marine H0's are essential in the maintenance and proper • 2functioning of cell membranes, e.g. active transport. Marine bacteria are also capable of growing at extremely low nutrient levels, although many will absorb onto detrital matter and grow under nutrient rich conditions. Since 90-95% of the marine environment is below 5°c, most marine bacteria are psychrophilic or • psychrotolerant. Most marine bacteria found are gram negative and motile. They are usually found to be aerobes or f aculative anaerobes, with very • few obligate anaerobes. Microbes can be found in photic zones of the ocean and serve primarily as a source of food for grazing animals and nutrient exchange between algae, diatoms and dinoflagellates . • It has been suggested that algal antibiotics keep bacterial growth down, but that dinoflagellates may require bacteria in the production of blooms .. Bacteria also provide growth factors such as viatmin B12 , nitrates to favor diatoms , and ammonia to favor blue-green algae . • -12 High bacterial counts can be found among the phytoplankton and immediately below, where nutrient remainder and fecal material can be found. The greatest counts of bacteria seem to be found at the surface of the bottom and in the sediment mud and oozes.(see figuret.. ~ The bacteria found in sediments are much more active biologically than in the waters above. Much more chitin digestion, decomposition of algae, nitrifiacation, reduction of nitrate, nitrogen fixation • and sulphate reduction occurs in the bottom layers of mud. In marine sediments some gram positive organisms are found e.g.Bacillus. The organisms associated here are primarily anaerobic and heterotrophic • relying on the settling material of organic material. Desulfovibrio organisms can be found in such areas and are known to reduce sulfate to hydrogen sulfide. Anaerobic methanogens are normally found in ~0 • sediment below the sulfate layer. Algae • Marine algae supply an essential input of carbon to the marine ecosystem. Unicellular algae make up most of the phytoplankton of the ocean. Algae reproduce rapidly when growth conditions are • favorable and produce blooms in association with flagellates ad diatoms. The single-celled algae may be nonmotile or motile. They are often associated in colonies, filaments, chains or other structures. • Algae cells contian pigments: chlorophylls, carontenoid2., and phycobilins. They are used in the absorbance of light energy during photosynthesis. Slight differences in the structures of the chloro-• phylls can determine the wavelengths of light employed and thus ·the maximum depth at which the algae can be found. Algae are subdivided into five phyla: Chlorophyta (green algae), e • -13 • Chrysophyta (several classes including diatoms), Phaeophyta (brown algae), Rhodophyta (red algae), and P~rrhophyta (the dinoflagellates) They are grazed upon by various zooplankton and other marine in • habitants. They are all photosynthetic organisms and survive in the photic zones of the marine environment. They~: i.are susceptible to disease by bacteria and viruses . • Phaeophyta are almost exclusively marine organisms. These include the kelps eg Fucus and Sargassum. They: are important in plant biomass. Members of the Chlorophycophyta and Chrysophycophyta are very• Marine plankton are found in high concentra prominent among plankton. tions in the upper regions of the ocean, usually 0-50 m in depth. Green algae are found in greater numbers near the surface. Red ~lgae and • golden-brown algae occur at greater depths. The Cyanophycophyta or blue-green algae occur primarily in shors-line sediment and estuarine environments. Th(:!se organisms • may grow in tropical waters. They are versatile organisms and able to grow in full sunlight or in almost completer darkness. The genera of Nostocaceae can precipitate out calciu~ carbonate by increasing • the pH of water due to the photsynthesis mechanism . . An interesting relationship can be described by some algae and zooplankton. The ingestion of Sphaerocystis by the waterflea • Daphnia actually enhances the growth of this algae. Sphaerocystis in the gut of Daphnia can obtain nutrients, such as phosphorous from the Daphnia metabolites. It can then pass through its gut and • back into the environment. • Zooplankton The zooplankton make up the whole of the heterotrophic planktonic organisms with animal nutrition. Since they can not synthesize their own organic needs they must obtain nutrients by ingesting • living or nonliving material. These heterotrophic organisms make up -14the second trophic level and are the primary consumer of phyto plankton. The zooplankton population is directly effected by the phytoplankton population as their major food source. The number of species of zooplankton is vast. Copepods being on if not the most • abundant animal populations of the world. Zooplankton populations also have incorporated into them a transitory group of organims which consist of larval forms of benthic and pelagic creatures. • Protozoa Marine protozoa provide an important link in the food web. • These organisms include flagellates, rhizopods, and ciliates and graze upon phytoplankton, zooplankton, and bacteria. They are very adaptable to marine salt concentrations found in various oceans. • Among rhizopods is the species of Foraminifera which are protected by a small shell, called test, are mostly benthic. Their shells fall to the bottom in great numbers forming the mud known as globigerina •ooze which covers wide areas of the ocean bottom. The ciliates employ the use of cilia on the external surface for locomotion. These cilia can be modified in many ways to protect • the organism. Cnidaria • The Cnidaria consist of two layers of cells -external and internal layer. They are carnivores and attack their prey with stinging cells, which inject venom paralyzing the prey. In this group are the • ' medusae which have umbrella or parachute like bodies with tenacles along the margins. The medusae have centralized stomachs for feed ing and swim by moving their umbrella-like body. This class also • conta ins Scyphomedusae or jelly-fish . Als o many speci es of this • -15 • type have a benthic larvae stage in their life-cycle. The Siphonophora are colonial organisms, and are connected by a stolon, common cord. These organisms possess a gas vessicle for flotation and • are suspension feeders. Ctenophora • These organisms are also made up of two layers of cells and wsre once classed a s Coelenterates. The Ctenophora are globular in shape with comb-like plates along the margins, they consist of fused • cilia. Also in this class are the Pluerobrachia which can contract their tenacles into its central mass . • Annelida/Chaetognatha This group represents the soft-bodied organisms such as Polycheata. These organisms are segmented worms which are covered with bristles, • they are planktonic and benthic carnivores. The Chaetognatha are transparent arrow worms with bristles near the head which act like jaws to capture prey. It's movement by up and down movement of its • tail, causing it to dart like an arrow. Crustacea • The organisms of this group include the Cladocera, Ostracoda, Amphidoa, Myseducae, Euphausiacea, and Decapoda. They are mostly transitory larval forms of nektonic organisms. The Copepoda are • the most abundant of the group with Calanus being the most commonest genus. (see figure1 ). Their motility is by circular movements of their large first antennae. The Decapodia are the most advanced • crustacea, most are benthic, but Sergestes is a pelagic shrimp. Mol lusca • Besides mollusca, this group contains the orders of Pteropoda, -16 Thecosona,and Gymnosoma. These orders employ fins ana cilia for • movement and feeding. Some possess shells while others do not. Many also use "bubble" floats for buoyancy. • Tunicata The Tunicata consist of a group which can filter nutrients to their cell body and may form large colonies. Some are also luminescent • and possessing transparent barrel-like bodies. Transitory larva • The transitory zooplankton include many benthic and nektonic larval forms. This group includes many copepods and Echinodermata. Most bony fish have planktonic eggs and larva which become available • in many food webs along with other plankton forms. Energy Cycles • Life cycles of the sea are powered by the sun's visible light. The ability to convert radiant or light energy absorbed by chlorophyll into useful chemical energy, namely ATP, is the process of photosynthesis In this mechanism chlorophyll absorbs light energy. Electrons in the chlorophyll increase their energy by gaining the light energy. These enrgized electrons are transferred alon a chain and ATP is • generated. Photosynthesis has some limiting factors in the water. The availablity of carbon dioxide, although rare, by indirect factors • limiting plant growth and reproduction and light intensity. It has been shown that noon light intensity reduces the photosynthetic activity of diatoms, chlorophyta and dinoflagellates. This is why • photosynthetic maximum generally lies j ust below tr-1e surface of tJv= • -17 • • • • I. • • • • • • water. Light is absorbed quickly with little of it penetrating farther than 450meters. Light intensity is also further reduced by turbidity and turbulence of the waters movements. Different parts q·';~. H1 · hit·..~-· o:t the spectrum are differentially absorbed, ·:x-ed wavelengths going the farthest. This can also account as a controlling factor in the horizontal distribution of many proto-and phytoplankton. Sulfur Cycle Sulfur is a relatively abundant compound and seldom does it become a limiting nutrient. The dissolved sulfate salts in seawater represent a large sulfur reservoir. The sulphur cycle is of next importance in the energy cycle to photsynthesis. It is this cycle that bacteria are abee to reduce organic matter. Sulphates are reduced to sulfhydryl or sulphides by plants, hetertrophic microorganisms and chemoautotrophic anaerobic bacteria. These organisms can act over a wide range of pH, salinity and temperature. The green and purple sulfur bacteria catalyse the anaerobic oxidation of sulphides while the thioaacilli catalyse the aerobic oxidation of sulphur to sulphate. Under aerobic conditions the final inorganic sulfur containing compound produced from the decomposition of organic sulfur compounds is sulfate. Under anaerobic conditions the final sulfur containing compound is hydrogen sulfide. Sulfate reducing bacteria include Desulfovibrio, Desulfotomaculum, and Desulfomonas. Many microorganisms and plants can utilize sulfate ions as the source of sulfur required to incorporate into proteins and other sulphur containing chemicals. Sulfate-reducing bacteria appear to be involved in the formation of sulfur deposits. Formation of mineral acid, produced by sulfur oxidation, can lead to the solubilization and mobili3ation of phosphorous a nd other mineral nutrients. Since the marine environment is poor in -18-;23o P content, this can become beneficial for other marine micnoorganisms •and plants. (see figure \2.) Nitrogen Cycle • Nitrogen does not occur in great amounts in the marine environment.The availability of N is a prime limiting factor for primary production in the marine ecosystem of the open ocean. • Nitrogen is an essential component of proteins, nucleic acids, and other cell biochemicals. The biochemical cycling of N is highly dependent on the acitivities of microorganisms. • In the marine environ ment, micro-organisms are responsible for the return of N to the water to be used by other organisms. Cyanobacteria eg. Anabaena and Nostoc in the aquatic habitat •are imp rtant bacteria as they are capable of fixing N from the atmosphere. Rates of N fixing cyanobacteria are generally tentimes greater than by soil bacteria. The energy required may be • obtained through the conversion of light energy iecyanobacteria. The product of Nitrogen fixation is ammonia, which is incorporatedinto amino acids and then proteins by amny organisms. •Ammonification is a process in which organic N is convertedto ammonia. In acidic or neutral aquatic environments, ammonia existsas ammonium ions. These ions can be assimilated by numerous plants •and microorganisms, which are later incorporated into amino acids and other N containing biochemicals essential for growth. Nitrification is brought about by bacteria. In this process • ammonia is oxidized to nitrite and nitrate. It is associated with planktonparticularly diatoms. Iron is a necessary factor in this process. (see figure lJ) • • -19 -23 I • Planktonic and benthic microorganisms are of extreme importance in the assimilation of carbon dioxide. This is done through the process . of photosynthesis and other energy giving cycles. The assimilation • of carbon dioxide can be performed by some organisms through the utilization of hydrogen sulphide or an organic hydrogen donor. Carbon dioxide is a necessity in the maintenance oc life in the sea as well as on land . • It could not be done without the aid of plankton, particularly the phytoplankton, and bacteria. • The plankton population has long been of interest to man due to their role in the food chain. Not only can they serve as protein directly, but they can also serve as an indicator of rich fishing • areas of the oceans. Due to this fact, muc h money and manpower is spent each year in search of these productive areas of the world. Today through the use of satellites and space shuttles man attemplts • to harvest t he sea as an alternative food source. Unfortunately, technoJ.ogy has also started to deplete this natural source 6f protein. Modern fishing techniques and poj;lution··:. have • destruction and decrease of the seas biomass . • • • • already lead to the I. -io .Z32.. • 90° , 80° l'. I. Primary production r-:-:-'1 100 r::::::::l 100 -150 \ (mgC/m2;doy) ~< ~ u. •· Distribution of primary production in the World Ocean (redrawn from KoblentzMishke ct al., 1970). sea surface (a) euphotic zone dork zone (b) (c) FMAMJJ A SO ND Fig...1!11!1 Seasonal productivities of phytoplankton and zooplankton. (a) North t temperate seas. (b) Arctic sea. (c) Tropical seas. phytoplankton • · • • • · · · • • plant nutrients ------zooplankton -· -· light intensity sea bottom ire ~Distribution of decomposer-bacteria in the open sea. Very high icrial counts are found immediately below the levels of maximum diatom growth, numbers fall off in the intensely illuminated surface waters and a lso in inter· ;ate depths, and the greatest counts ere found at the surface of the bottom nit. ... l 1 -· ·L (a) ~33 I (b) ~.,, i (c) (d) HO '400 500 600 700 Wavelength (nm) ..... · Spectral distribution of radiant energy at different depths in dear ocean water. (Redrawn after JERLOV, 1951). • (e) J FM AM J JASON D CJ t Seasonal amplitudes of phytoplankton production. (a) Arctic seas. (b: North temperate seas. (c) Tropical seas. (d) Antarctic seas--northern region. (e Antarctic scas--southem region. ----··-·4--·--·.....................,...._,._ .._.. c 0 ·g c 0 I l .n C'J 100 .i Q) 50rn > .\ ·;:, C1J Q a:: OL.__~.l-~...L~-1...~~~___JL.-~.l--L~---1.~--l:-::--~..__---'~--:-'---:~. 400 500 600 700 4-00 500 600 700 A.(nm) .J• !.-Relative absorption by phytoplank~on (the·~aximum absorption is equal to 100) of the available light energy at different depths m oceanic water (after Yentsch, 1962). -·----· .. ·------------- -· ··T'-·-·-··i I i t -J_ I •,I • • f t ' ,I • • i~ I3asic syst<'m of surface currcnts:(By kind permission of thl' Trustees of the' British Musl'um (Natural History).) • _.,. l '·""''' .. -...... . .. .. I .... ..,,. --- -------.. Ii·· · l11·f H I !. • .,,,_""' --- ---------I .1 · ' . .. · 11111ltr1al ... 11!1 ., ... ----- ------I I·~· llt1111 ----- ---0--... i 1 ; 1 1:~,t·r... t' furr1 •\' • ----- -• I I . 1 •· ·t 111..-11 ! I . • --------• I· laizr·flurn I I • ~Dinoflo1:rllate morpli11lugy. • • ·I i ---~--~~~~~~--------------------------------------...--------~~ \n t"1 ro .,J Ci SlJNl IGHT \ \ \ \ \ \ \ \ \ \ ~~~~~d~~~~~~..~-0---~ /t:fti ._1..·-sEAwErn ~(!'_-, _.-;e lAllh cfJ:Jt.Y ~~ ~;/(',j, -il:_,:;-· ~({J! . . ·;·;·;· ···.. Q···\,...:."-· /·. · _ .. ' . .. -.· ··----.~~·'... ..,.. -. · ,._· ;.. UTTOR.:.L EENTH 1C .-_ zo~1E :-.:_ :j'•''( . ·..,;_;,., .-P" --!('J:J.,r"-'-'i. ·· . \.::::? ~-::f" ---~I'~~ --Jtl · ".-l}f . o Bt!J -i-~ .-~---> "" : .t ,.. .. -~ ~ ... ~9- "-·;,f>-:'Jr \; rnAro,,s~ -r .,_ 0, J. .~~~ ·1 .1,il' 1. ~) ~-®~®61 P IJ 0 1P frl :f:~ '!)~,~J ~ ~0~,4;~ -k' CRAB LARVAEIf {! .!iU7 PTEROPODS jJ SALPS @ HH=::7t\\~ ..·1~ ~rES ~' .• . ~".-.. c·· '> '· ·z~5:\··=~%;:. '. rt ·:) . "',.. .. x--c .. •: -~''-1.'.)~. WORMS \.~::.: ~·;;..; ; ·.·.-._ T;°J -g- _:·~ 86 :1> .~ .''._,. ::_. ~. SABLEftSH TABLE 11 The Contribution of Different Types of Sea).''f1)i·'.~i· ···. Area to Fish Production (Ryther, 1969). Ocean Area ~.~ 361 X 106 km2 Pe:~cca~t(~e uf ocean Prim;.iry production kcalm-::yr-:.(P 1) Eculog;cal efficiency pee trnph:.:kvcl,(c} Number of trophic levels ~~:j!f!~~~;;;~~:~~~~ 2 kcal m-yr-1 (P 1en) Tora! fish production 106 tons/rear (Using . Winbcrg's transformation 1 kcal = I g fish flesh) (3.61 a P1en) Percentage of fish ---~r_<..~~~~~un ..... Type ur' Sc:;.i Arca Up\\ di inf: Coast;.il Ol-l' ;.inic \ ~ O.l7c 9_9% 907c \~~~~~fr~::;_\:,:' :_~ \ ~ . -->.;. : ' ·~ _ 3,000 1,000 500 1_ \ '.:; '·.i \.~~ \ 0.20 0:15 0.10 ,:::-~\ . · :_'_;:~ 2 !·: 10-~.~ x 10-3 ~ox 10-s '.:'0:Y:~~~; 270 3.4 0.005 • 98 122 l.6 4~--; liJJJJt..,~_ • 54 r; •' ·'/ •rnNGH~ :.:;~~' =-~---- ~ r' r '""'.=-~'==<:-<-~:-.;_ ?'ii~ _:__·---c-c::c~~=-' --. <::'. ~!~ ·";;,, ~----...... ....~ ~-;r:v:·-:;::~~7' DOLf'H!I JF:::.H ~ "'-::-~~- ~.r.~::;:-~-~·~~--::.i· ~!!.J.::~ ~/'..'' .,_._._ ·: ·-..:.., &":-~ . ;,;,;" """'' """"'" '"'·';;.-('" ~' . · ·····~,,,~ ~~~~~~,~·~23; Cf~\? ~·--·-·~- '-'" •) . -~ ~--·'-";~:.;.-:;~;;t=·-./ . , ;=~-~ -'"'"· ~~~~,~ -~~~...,, fl ==-~, , < ~"";:..~-, ''<-' '.·"'-' ~,.._(;¥) . •. _,.,. ~~,~~ ~~t._ SWORDFISH NEKTON l'f' ~~~ ~~ L~~ i f'. •>.: LANTERN FISH ti:, .~ ~~--~.~~ . · . : .. . ..$ ,.: y-' ® • ' ''' ~, • LARGE SO~t: ,~HATCH~'5H .··,. .i ~ t -, ·~ _-.,-µ ~ '.,._. .. . \· .. .• . ----) . ~ ~-. ·/'~~-... ~ ' SCARLET PRAW'5 • • 'W" · r11fJ!P. · , VIPERFISH ANGLER FISH ~ ·. ~-·. ~ ~ SWALLOWERS w .-::··--_:;s~ GULPER . I • . . -~;;c· \,;} • . , "'· -~ ~,\\ i/'.·~~ . ANGlER"SH ~: . .··r.. 0 t ~ • • ~ ,GLl,l:,::,:-,P\)NGES . > · · . '1°7~-~::---z3 / • ; .~7/J_ • GRENAD:~ • I • ' ]~;;~:,; ': : -If:" ! --1~.. ~· --=~~ ; ---··--· --· ~ ~ ~ .:::-c: ('('\ I ~ ~ - -· lBI limbs left outer ____-/ . •J, i4. ··.....:..... ... vortex figure ~. Feeding in Ca/anus. A: The filter formed by the setoe of the second maxilla of Ca/anus with a food diatom Choetoceros, drawn to the same scale. 8: ·, Lateral view of a living Co/onus. C: lateral diagram of the vortices created in swim· ming which bring food particles into the midline and through the maxillary filter. [from W. D. Russell-Hunter, A Biology of Higher Invertebrates, Macmillan, 1969. A: adapted from S. M. Marshall and A. P. Orr in J. Mor. Biol. Assoc. U.K., 35:587-603, 1956. B: Photo © Douglas P Wilson. C: adopted from H. Graham Cannon in Brit. J. Exp. Biol., 6:131-144, 1928.J F~, I ~ left outer swimming vortex Figure e. Feeding in Calanus. A: Dor5al vie N of a living Co/onus. B: Ventral diagram of the vo1tices created in swimming which bring food particles into the midline and through the maxillary falter. [A: Photo © Douglas P. Wilson. B: adapted from H. Graham Cannon in Brit. J. Exp. Biol., 6: 131-·1.44, 1928.] ·-·-------------- • NITROGEN Algae Oenitrlfying bacteria • Photosynthetic bacteria Phytoplonkton NITRATE & NITRITE--------ORGANIC NITROGEN (/.mino-nilro9cn) • SULPHUR AMMONIA Beg91otoo Thiobocillus spp., ~.Themicrobial nitrogen cycle. • Achromobact~r c pt in ovorum Nitrogen cy;e ~2 ..... NH:i or -NH2, electric storms; blue-green algae in estuaries, coral reefs and tropical oceans; anaerobic, Thiobacillus spp autotrophic ~1nd heterotrophic bacteria, .SULPHIDES SULPHATES EschHichio Qq:sulphovibrio mainly in sedi:J1enrs. Acroboct er q:tc . • NH:i -~ 1\:0:! -• NO:i, nitrifying bacteria (mainly tn sediments). denitrifrina bacteria (pseudomonads). . b Esctarich io Protrus in algal cells. • SULPHUR-CONTAINING (deamination) b:.lcteria and autolytic. AMINO-ACIDS :\"irrification is exothermic in aerobic environments, endothermic in anaerobic svsrems. 1l I • SULPHUR-CONTAIN ING PROTEIN ~licroh1al flora nf t!ic surhc~ i-.The microbial sulphu~_cycle. t-Pf1):l0i)ia:°'J.:t(~-1 t'l•>tlC zone ! Nun~photosynthctic micrrwrga~.:sms Protoµla.-.::·: ~~ -----.\mµle l!ght rnr =I FlJcteria a"d runc:j S11(/itr t:J•rle 1.t,.·•t fJsynth<:>sis i ~ i l'hvt<•j,b~ , us an;mals includi:-.,: fish __ 0 t'"•1 •. 1~~:;~~~~~~;\e_ __ _ ~i ~~~:E:;;~'~,aj;~1 ;,,},-~;1~r•ti!:~~~::~-;r-~ j -so~ ·-· H~s, (exothermic rn anaerobic em·ironments ICarnn·vre; zone da1!y ~· abiological: Dtmljoz1ibrio. 7~~~~~;;:;?::g_J.'r~~---:r:·s;.;;-1,;1>r;:;;or1;,·&1~,n(S-;-;-,1;r..;:11;:: c"hfor~;;F::-T:1-- '.\t1d -'4·a1f' r biociicnosis Some htrl.Jin1rf's (<.'<•pc·pucb. (-'.(' 1 <)·:II· l1 ~ht fn,rn -SH--· H~S, facultari \ e and obligate heterotrophic a1 ll•·t•p b1nc oc11e1si s ~; anobes. <" <.1r:: e pr1,t opl:i :-.~:: .· 11 :1'.Ht, prf>Sumahly. t·e rUit·orcs • ~ "' I (anaerobic) green sulfur bacteria, purpk sulfur bacteria, photocatalyric \Vith Fe : Thiobacillw denilr~/icans; (aerobic) abiological; a Oceanic zones and their biocoenoses. Depths are o~ly approximate and n1ry cunsidcrnhly in dirfercnr localirie5. Thiobacilli and other sulfur-oxidizing organisms, e.g., Thiovul11m, Thiothrix, Begg/ato,,'. • s -so~. (anaerobic) purple sulfur bacteria; (aerobic) T hiobacilli. • • Bibliography Atlas, Ronald M. and Richard Bartha. Microbial Ecology: Fundamentals and Applications. Addison-Wesley Publishing Co., Reading,Mass. ,1981 •. Boney, A.D. et al. Phltoplankton vol. 52, Studies in Biology.Edward Arnold LTD Crane Rassack. London, 1975· Collins, M. "Algal Toxins", Microbiological Reviews.Dec. 1978,pp725-746. •Dunbar, M.J. Marine Production Mechanisms: International Biological Programme. Cambridge University Press, London, 1979; Hardy, A.C. The Open Sea. Houghton Mifflin Co: Boston, 1956. Jannasch, H.W. and C.O. Wirsen. "Microbial Life in the Deep Sea."Scientific American, vol. 236, no.6., pp42-51. • Johnstone, J. and A. Scott, H.C. Chadwick. The Marine Plankton.University Press of Liverpool: London,---r934. Kinive, Otto. Marine Ecology vol. IV. Wiley-Interscience Publishers: I1978. Parsons, Timothy R. and Masayski Takahashi. Biological Oceanographic .-)Processes. Pergamon Press: London, 1973. Raymont, J.E.G. Plankton and Productivity in the Oceans. MacMillan ICo.: New York, 1963. Steele, John H. The Structure of Marine Ecosystems. BlackwellScientific Publication: London, 1974. Wickstead, J. Marine Zooplankton. Camelot Press LTD: Southampton,1976. t Wood, E.J.F. Marine Microbial Ecology. Reinhold Publishing Corp.:New York, New York, 1965. Wood, E.J.F. Microbiology of the Oceans and Estuaries. ElsevierPublishing Co.; New York, New York, I9b7. I • • A Sewwvv J. ·D.dla~ fJv • ..?.39 lh o~~c, M.CAhmJ :Pr('SeV'\t l/1;:50\ved Or50.V\~v Vl a.terio.~ eoi. Sunlijn\ (~ 200t'Yl) Oe~~1~VS -·---~ M~Ja.bo~les • }-l1urDbe~ I• • • 11. Continental Shelf -Pelagic Jeff Heimann • • I. Geographic II. Geologic: plate tectonics • III. Sedimentation IV. Isostasy V. Glaciation I VI. Chemistry VII. Salinity VIII. Temperature • IX. pH X. Light XI. Limiting Nutrients I XII. Other Interactions XIII. Energy Production XIV. Other Effects of Man • XV. Bibliography • • • Jeff Heimann 457-06-3471 • 11. Continental Shelf -Pelagic Geographic: • The continental shelf is the submerged land extending from the low tide line seaward, until the bottom slopes sharply toward greater depth. Continental shelves exist adjacent to, • and as a part of, almost all major land masses. The shelf varies in width from almost 0 to 1200 kilometers. ( 750 miles ) The average width is 78 kilometers ( 48 miles ). The depth • of the seaward edge of the shelves ranges from 21 to 621 meters. The average depth of the continental shelf is' 133 meters ( 506 feet ). The slope of the shelf is generally less than l 0 with 0~07~ • being the average. Approximately 7.5 percent of the world's oceans are included in the continental shelf zone. This is equal to eighteen percent of the total world land area• • The pelagic province extends seaward from the low tide line and includes all free swimming (nektonic) and free floating (planktonic) organisms~ The portion over the continental • shelf is termed the neritic zone. This report coverage will range from 65°north to 65Qsouth and will specifically exclude the arctic and antarctic regions. The area studied will in ~lude • a very significant portion of the total world area• • • • Geologic: plate tectonics • The widely accepted theory of plate tectonics has important bearing on both continental shelf formation and size. The Atlantic ocean is a large zone of sea floor spreading • along the mid-Atlantic ridge. This ridge is a boundary of four major plates; the North American, Eurasian, African, and South American. Production of new sea floor material • is expanding these plates and pushing them outward from the ridge. As these plates increase in size and move away from the mid-oceanic ridge they must move somewhere. The result I is a decrease in the size of the Pacific plate as it is subducted under the edge of the North American, Nazca, Eurasian, and Australian plates. This subduction is a result of the lighter I continental rock (sial) floating up and over the converging, heavier oceanic basalt (sima). The typical Atlantic continental margin is a result of I little subductive activity and is characterized by a generally wider shelf zone, continental rise and abyssal plains at the base of the continental slope. This is indeed descriptive • of continents bordering the Atlantic and is due to the fact that the continents are a part of the major plates meeting at the mid-Atlantic ridge. • The typical Pacific continental margin is characterized by a narrow or non-existent continental shelf and oceanic trench at the base of the continental slope. The cont~nental • 2 • • • rise and abyssal plains are usually absent. The oceanic trench • and narrow shelf are products of the subduction processes which occur along converging plate boundaries. As the oceanic sima is subducted beneath the continental sial it produces an oceanic trench; and also Benioff zones of earthquake and volcanic activity. All of the continents surrounding the Pacific ocean are charac• terized by this of margin. This explains the narrow shelves and deep trenches common off the western North and South American continents. Similar features are found off the eastern coast • of Asia. • Sedimentation: Continental shelves are formed by one of two methods• In one type igneous rock material underlies the neritic zone. The other, more predominant type, is composed of sedimentary rock • deposition. This sedimentary rock is almost totally of terrigenous • origoR. In sediment depositional formation of continental shelves, a dam of some type catches the sediment and forms the edge of the continental shelf. This dam is usually one of three types; • a) an igneous upthrust block, b) algal/coral reefs, or c) ex truded salt domes. An igneous upthrust block is a faulted block of igneous origon which serves to catch and maintain the • sediment deposited. The shelves rimming the Pacific ocean are .typical of this type of formation. Algal/coral formations serve similar functions in tropical and subtropical areas• Areas around Florida, the eastern coast of Central Americ~ 3 • • and the northeastern coast of Australia are good examples of • this type. The salt scirusions are forced out of fissures by the w~ight of overlying rock. Salt dams are the type of dam found around the rim of the Gulf of Mexico, the eastern • shores of North America and the eastern shores of South America. These dams have lang ago been covered by sediment and the shelves are now maintained by the angle of repose of the sediments. • shore The angle is usually steeper near~due to higher depositional rates near shore. The average sediment thickness is estimated to be approx-• imately two kilometers (1.2 miles). Sediment rates are estimated at twelve cubic·· kilometers per year and total sediment accumulation is estimated at fifty million cubic kilometers. Major derivation of sediment is thru river discharge. Other methods of importance include airborne particulate matter, rainfall precipitated matter and various nearshore currents. • Isostasy: An important concept of current geologic theory is that of isostasy. Isostasy is the equilibrium attained when the • continental sialic material "floats" on the heavier mantle rock. This equilibrium is a balancing of the weight of the c:Ontinental mass and the subsequent displacement downward of the mantle • material. As material is removed from a continental area by erosion or thawing of glaciers the underlying material tends _to::rebound or rise up to new isostatic balance. This • • • • is thought to have had important effects on continental shelf depth in certain areas of the world. Northern North America, Europe, and southern South America are all areas of isostatic • rebound. Glaciation: Another important influence on continental shelf depth, • width and size in general has been due to the gradual melting of extensive glaci ers of the late Cenozoic period. This sddition of previously frozen water is estimated to have raised the sea • level as much ~s 130 meters. Underwater continental shelf river valleys and fiords; along with fossilized animal remains seem to support this theory and the depths hypothesized. • This possible change of 130 meters in ocean depth would obviously have had a great effect on the shelf zone, whose present average depth is only 130 meters. What we know now as the shelf zone • would have been composed of inlets from the deeper ocean during the latest period of intense glaciation. Chemistry: • The general composition of near shore seawat er has the -+ 2 sam e basic components; chloride ( Cl ), sodium (Na ), sulfate (so4 ), 2+ . 2+ + magnesium (Mg ), calcium (Ca ), and potassium (K ), as open • ocean water. Open ocean areas have somewhat more stable concentrations than nearshore waters due to less influence by river influx and land i nfluenced climatic patterns. The seawater of • the shelf area is more variable in salinity and chemical composition as a result of more dynamic processes closer to land. 5 • Salinity: • The salinity ranges from 33%oto 38%0 , With values outside this range possible in areas of extreme evaporation or precipitation dominance. At the mouth of rivers such as the Amazon, • Mississippi, and the Yangtze salinities are usually less than 33%~, while in higher evaporation marginal seas . like the Mediterranean or Gulf of Mexico, salinities of greater than 38%aare common. • Temperature: Temperature is largely latitude dependent with important influence by prevailing ocean currents. Temperature values • range from 8QC or less in regions near 65°north and south latitude, to more than 30°c in equatorial regions of intense • solar radiation. Seasonal climatic changes influence temperatures of surface waters. Fluctuations of ten degrees or more are common in temperate zones. This change due .to the change of incidence of solar radiation is minimal in the tropical latitudes • and maximal in the higher latitudes. Particularly important in baseline temperature patterns is the pattern of prevailing oceanic currents. Currents can • as raise and lower water temperatures as much~te~· degrees relative to surrounding water temperatures. Current temperatures are generally warmer on the western edges of ocean basins and • colder on the eastern edges of these same basins. This alteration of temperature allows organisms to inhabit areas that would be uninhabitable to them. • 6 • • f jpH: 0 Ocean water is generally well buffered by the carbonate cycle and pH's are maintained at between 7.5 and 8.4. _ This • relative stability is very important, as small pH fluctuations can be fatal to many organisms. pH variation in the pelagic shelf environment is influenced by dilution from river influx • and excessive evaporation in marginal areas. Physics: wave action The major importance of surface, standing, tidal, and • internal wave.·action is to thoroughly mix the seawater of the pelagic shelf zone. In the absence of a strong thermocline, these waves can effectively mix coastal waters and alleviate • some nutrient traps. This is an important contribution to the comparatively high primary productivity of the shelf zone. The driving force behind surface waves is the prevailing wind • pattern. These direct and drive the all important nutrient carrying and temperature regulating currents. The failure of the wind driving these currents can have catastrophic effect • on the life which is dependent on them. An exceptional example of this failure, is the periodic failure of the Peruvian current. water The Peruvian current blows surface+away from the shore on the • Peruvian coast. This allows deep nutrient rich water to upwell and replace nutrient depleted surface water. The rich water normally maintains a very large anchovy population. When • the Peruvian current fails, upwelling ceases, killing off huge plankton populations. The dyifig~plankton pollute and poison 7 • • the water, causing massive fishkills. This is but one example • of current importance. Light: Light is one of the most important factors in the pelagic • she1r i vi.romnent. It directly controls primary productivity throll»€h energ~ input controls. The most intense solar radiation is ear the equatorial region. This is due to the path of the • light r~s b~g al.moat perpendicular at the equator. Energy per unit area of water surface is greatest. Also the light passes through the least atmosphere near the equator and less • light energy is absorbed andior reflected. In open ocean areas, the depth at which one percent of the incident solar energy 1• available is frequently 100 meters • or more. In many regions over the continental shelf, water turbidity and organism abundance limit this to twenty meters and less. Water turbidity CAU§@~ li~ht aoattering and penetration • reduction, while high organism growth rates often cause shading out due to absorption of light by phytoplankton. Both of these phenomena are common near river discharge areas of high sediment • and/or nutrient input. The depth at which the light becomes too taint to support photosynthesis is known as the compensation depth. This is • at the bottom of the photic zone and is generally equal to the depth at which light intensity is equal to one percent of the surface intensity. This depth can vary from over 200 meters • 8 • • • in tropical areas, to virtually zer9, at high latitudes in wintertime. oversaturation with light can result in little or no growth. This is often the case in tropical regions, • at or near the surface. Meteorology: climatic patterns Equatorial regions have warm surface waters throughout • the year. High evaporation rates causesheavy precipitation and low surface salinities. Vertical water movement promotes !~ -~ upwelling and increases in productivity. Winds are almost • nonexistent in this the doldrum area. ~ ~ Tropical regions (0-20 latitude) are dominated by the tradewind~ blowing from the northeast in the Northern Hemi~• sphere and from the southeast in the Southern Hemisphere. These winds cause strong equatorial currents which originate in subtropical regions of higher salinity. Rainfall is usually • plentiful. Subtropical areas (2~-40°latitudet~ ) are characterized by ststionary high pressure systems with little horizontal wind • movement. These are called the Horse latitudes. Evaporation is dominant due to low rainfall and abundant sunshine. Salinity tends to be relatively high (39%o+) • • The temperate zone (4~-6cf latitude) is dominated by the Westerlies which produce strong wind patterns and corresponding strong water currents such as the Westwind drift. The result • is extensive mixing and nutrient replenishment from deep water • • leading to high productivity. This zone is center of world • exploitation of marine food products. ~~c These are general climatic tendencies which~latitude dependent and are strongly affected by land masses. Fluctuations • in these regional patterns are produced by seasonal variation, which tends to shift patterns north or south, depending on the time of year. • Producti~ityJ nutrient replenishment The three most important methods of nutrient replenishment are land runoff, current mixing and upwelling, and biological • cycling. Land runoff is importan~ especially near large river mouths. The nutrient flow is relatively small when compared to the total • ocean. Even so, it can have great effect on localized increases in productivity. Nitrogen compounds, and occasionally phosphorus, are the major limiting nutrients in seawater. Runoff can • replace usable nitrogenous compounds, with nitrogen fixed by terrestrial and aquatic organisms. Phosphate is replaced with phosphorus in organic debris, and by that leached from • continental soils. Much of these nutrients sre used by organisms near the discharge site. Gradual transport and dispersal takes place through vertical and horizontal distribution. Currents help disperse nutrients over great distances. The Gulf stream • is an example of warm water nutrient transport. Organisms are most important in vertical distribution, as various levels • 10 • • • of producers and consumers reuse nutrients until they eventually become trapped in sediment deposits. The mixing of nearshore water helps maximize nutrient benefits. Productivity is low in subtropical zones, because of nutrients being trapped beneath • the permanent thermocline. The Coriolis effect causes the western currents in ocean basins to be warmer, faster, and deeper. Eastern currents • are colder, slower, and broader. The Gulf stream and Kuroshio current are examples of western currents. The Canary, California, and Peruvian currents are eastern boundary currents. Prevailing • wind patterns cause western ocean basin waters to pile up near shore. This pileup retards upwelling and leads to nutrient depletion. Primary productivity is generally lower on the • western side of ocean basins. The same wind patterns blow water away from eastern boundary shores and promote nutrient rich upwelling. A good example of this is the Peruvian upwelling • previously described. Although, both land runoff and currents are very important in the high productivity of the pelagic shelf zone;bio~ogical cycling is in many instances1 of equal • or greater value. Biological cycling is the mechanism by which organisms reuse nutrients once they are brought into the ecosystem• Nitrogen can be fixed as Noby processes such as lightening, 3 bacterial activity, and by certain blue-green algae. Once • fixed, other plants and animals can utilize the nitrigen for , 1 • growth and reproductive processes. Excreted waste and death of the organisms provide debris for decay by bacteria and fungi. Bacterial denitrification releases Nand nitrosification 2 forms N02 • This N02 can be nitrified into Noby the addition 3 of o2 and energy. This simplified description outlines some of the complex activities required to maintain~ nitrogen in usable form. Phosphate is also continually recycled by bacterial activity and by leaching from dead plant matter. Phosphates readily precipitate out of solution attached to calcium and other compat~ble ions. Limiting nutrients: Nitrogen: phosphate ratios,in the tissues of living organisms a.re typically on the order of 16 : 1. Nitrogen concentrations are five times those of phosphate in normal seawater. Thus times nitrogen is roughly three1more limiting than phosphate in average environments. Other trace elements and vitamins function as micro-nutrients, and can be limiting in special situations. These incllfde vita:nin B 12, biotin, and thiamin. Actual productivity: seasonal variation As previously described, actual productivity varies according to the depth of the photic zone, nutrient availability, and light availability. In equatorial and subtropical areas, productivity is year round, with nutrient depletion being the limiting factor. In temperate zones, nutrients are generally more readily available and productivity is~ more seasonal due 12 • • • • • • • • • • to light and temperature dependence. In high latitudes, product ivity is highly seasonal, with a high rate of short duration, during peak light availability. (figure 1) • Actual productivity estimates : The open ocean is generally lower in nutrient~ being farther from nutrient sources. The much greater depth allows• nutrients to sink out of the photic zone, further reducing productivity. The sheer volume of the open ocean, allows it's total Productivity to exceed that of the pelagic shelf zone• • However, a comparison of grams of carbon fixed per surface area, illustrates the greater productivity of the shelf zone. Open ocean rates of productivity average 25-75 g C/m2/yr• • The average over continental shelves is estimated to be 100 g C/m2/yr. Localized upwelling regions can have rates as high as 10 g C/m2/day. The average productivity rate of coastal upwelling • ~ 2 zones is about 300 g C/m /yr. These estimated figures detail the importance of coastal areas to total world productivity. Biological interaction: food webs • Food webs attempt to explain the complex interactions of primary producers, primarv consumers, and predat*>r-· -prey relationships. Different specific organisms can occupy different • places in the predator -prey role as differ3nt levels of each and/or both at the same time. In the pelagic shelf ecosystem, the wide diversity of specific organisms and variable living • conditions allow infinite specific trophic interactions. • • Primary production by photosynthetic algae and bacteria • forms the basis of life in the pelagic continental shelf eco system. Primary consumers ( herbivores ) utilize the the primary producers for nutrient and energy requirements. • The picture begins to complex considerably, with first carnivores that feed on primary producers and consumers. Higher carnivores feed in complex patterns, on each other, and on~ ·va~ious combi • nations of trophic levels beneath them. The top marine carnivore in the pelagic shelf area is the shark. Man is also on a .i. level similar to that of the shark. Toothed whales, mackerals, • tuna, barracuda and other similar fish are second and third carnivores. Smaller · fish such as sardines, anchovies, menhaden, and sauries feed at the first carnivore and primary consumer • levels. A typical food web up to the first carnivore -second carnivore level is illu~~rated by the herring in figure 2. be • Above the herring would?further levels of predators such as tuna, mackerals, and sharks. Man would also occupy a prominent position since herring is an important commercial food fish. Other interactions: • As in most environments, symbiosis is common in the pelagic shelf ecosystem. various symbiotic relationships exist,fiincluding commensalism, mutualism, and parasitism. Social behaviour • is also common in some organisms. Examples of commensaiism include, remoras attached to sharks, pil ot fish, also associated with sharks and the functions • of some of the various cleaning organisms. The remoras and 14 • • pilot fish receive increased food supplies and protection, • without the shark receiving any known benefits or being harmed. The cleaning fish can be an example of mutualistic relationship. They receive food and protection,and in turn rid other fish of lice and parasites. Although, most pelagic animals are not parasitic, some planktonic larval stages are parasitic in • one or more stages of life• • The social behaviour of schooling animals is important their survival. Schools are generally aggregations of similar size and species of animal. Many species of fish, a few types of squid, and some large crustaceans tend school. Schooling is thought to be a mechanism to limit predation. This may • appear contradictory in that large concentrations of fish • might invite predators to fill up. This very mechanism provides statistical safety, in that a predator can only consume a certain number, no matter how many are present. Concentrating the population protects it from the many predators, which can not all be present at once. The regular spacing and coordinated • movements, of schools is thought to discourage predators by appearing to be a single large animal. Competition and population equilibrium: • The competition of organisms in the environment serves to establish equilibrium with one another based on nutrient • availability, predation, and spatial distributions. When various parameters are changed, corresponding disruptions of • • the equilibrium occur. • A-~common example of equilibrium disruption, is that which is caused when Gonyaulax, a common dinoflagellate, blooms due to exceptionally favorable growth conditions. Toxins • produced by this organism cause paralysis and death in many fish, and other organisms. Massive fishkills are common during such dinaflagellate blooms. Another example of periodic dis • ruption, is that which is caused by failure of the Peruvian current. Thi:sis known as " El Nino " because of the close occurence of it and Christmas. " El Nino " was previously • described under the effects of wind. Flora and fauna: micro Zooplankton and phytoplankton are the main components • of micro flora and fauna. A'description and characteristics of plankton of the pelagic continental shelf zone, will be found in the section especially devoted to this important subject. • Flora and fauna: macro Latitudes serve to delineate ranges of species of fish and other organisms. In general, organisms found in similar I latitudes, are usually quite similar in physiology. Nutrient requirements and overall living conditions are very similar. An example of this is the close similarity of California and I Japanese sardines. Many examples of close similarity of organisms of similar habitat requirements exist throughout the world. • 16 • ~57 • Pelagic organisms are adapted to a life of free swimming and free floating existence. Various adaptations have evolved in all pelagic organisms, enabling them to better cope with • maintaining a position of maximum advantage in the water column. Many planktonic life forms have densities near that of seawater. This adaptation, along with body shape is most important • in slowing the rate of sinking out of the photic zone. Gas filled bladders,. a •.common adaptation in fish, allow voluntary depth regulation. In fish without swim bladders, almost continual • movement is required to prevent sinking. This is the case with sharks and many very active pelagic fishes, such as tuna. In tuna, as well as many sharks, muscle activity is increaeed •• by elevating the body temperature. This elevated body temperature increases chemical activity and reaction rates, allowing increased muscular efficiency. In tuna, body temperatures, as much as, • twenty degrees above ambient water temperature have been recorded. The elevation of body temperature requires energy input and accounts for the voracious appetites and high energy of many • pelagic fishes• Another important adaptation in tuna,is the highly efficient countercurrent system, which increases oxygen levels necessary • for increased metabolic activity• These are but a few of the many adaptations which allow pelagic organisms to .better cope with their environment. • Man's interaction: exploitation Man's greater and greater involvement, in the continental 17 • • shelf area, has increased his impact on the pelagic ecosystem. • So~e of man's practices have seemed to benefit the environment, while others have seriously damaged it. Energy production: • Much of man's activity on the continental shelf is centered around the production of energy. Oil and gas production is the • associated with some oftmost biologically productive areas in the world. Occasional oil sp±lls have had seriously detrimental effects on life in the immediate area of the mishap. At present there is heated debate on the long term and long distance • effects of these oil spills. Some scientists argue that the volatile, ~most toxic components of oil are quickly lost to evaporation, and pose little long term threat to the environment. • Another argument is that natural continually occuring seepage and biologic formation of hydrocarbon compounds, is of more quantitative importance. While this may be true, naturally • occuring hydrocarbons are not nearly as concentrated,as massive oil spills limited in geographic area. These and other unresolved issues should be seriously considered, in order to avoid excessive • contamination: of biologically important areas, which could later prove more detrimental ever imagined. A·positive contribution of the oil production industry • has been the vast increases in habitat provided by oil production structures. These sttuctures provide additional substrate: in otherwise substrate limited waters. This increased substrate • 18 • • • seems to greatly increase the numbers of structure attracted species such as dolphin (Goryphaena htppurus~, cobia (Rachycentron canadu!), and great barracuda (Sphyraena barracuda) • • These fish seem to use these ':structures· for orientation and have appeared in areas which were formerly uninhabitated by these species• • Other fish attracted by oil platforms, include King mackeral (Scomberomorus cavalla), little tunny (Euthynnus alleteratus), and jewfish (Epinephelus itajar). These species seem to be • attracted by the increased abundance of food near and on the platform structure. As iong as pollution around these platforms can be controlled, benefits to the biota seem positive• • Fisheries: • Continental shelf fisheries have important food providers for many centuries. Both the closeness to man's home on land, and the high productivity of pelagic shelf area~,Thas caused ever increasing exploitation. Annual world fish catch is on the order of 100 million metric tons.1 As world population • continues to grow, mankind will look for ever increasing food • needs in the world oceans. Currently clupeoid fishe~ such as anchovies, herring, and menhaden are the most important as measured by tonnage. Gadoid • fishes rank close behind clupeoid fishes in gross tonnage. Other fishes, mollusks, and crustaceans provide a significant portion of the world fish catch• • • Historically, the major problem of the world fisheries • is that of, overexploitation~ An example of this is the collapse of the Peruvian anchovy fisheries in the early 19?0's. Continued harvesting at levels beyond those established as the maximum a • sustainable yeild, resulted in'f'decrease in anchoveta catch, from 13 million metric tons in 1970, to only three million metric tons in 1973. Similar fates occured in the Japanese • sardine fishery in 1958, the California sardine fishery between 1938 and 1967, and the sauries fishery. These are but a few examples of improper resources management. In the future, • better communication between scientists and econQmically involved individuals, will help result in better resourdes management. Other effects of man: • Other important effects of man on the pelagic shelf environ~ ment,,have resulted from increases in chemicalsand the alteration of river discharge by construction of numerous, ' nutrient and • sediment trapping dams. Pollution control seems to be taking a turn with increased awareness, and stricter enforcement of anti-pollution regulations. • As a whole world wide cooperation is the vital link in better utilization of finite continental shelf resources. • • • 20 • • high _ .,·-~ latitudes • \ "\ \ I \ / \ / l "ii\ • \~ _/ _____.. _... .... -----------------------·~-----·------·-r--·-·_..______ • temperate latitudes • TJ • increasing I productivity f I tropical I latitudes z • r . .. • seasonal variation in primary productivity • figure 1 • • • • • • • Barnacle larvae • • Typical food web figure 2 • • • • • Bibliography Battaglia, Bruno et al. 1972, Fith European Marine Biology • Symposium. Piccin Editore, Padau & London Berry, A. J. 1975, Physiology and Behaviour of Marine Organisms.Pergamon Press, Inc. Maxwell House, Fairview Park, Elmsford, New York Dunbar, M. J. et al. 1963, Marine Distributions. The University • of Toronto Press, Canada Ekman, Sven 1953. Zoogeography of the Sea. Sidgwick and Jackson, Ltd. London Friedich, Hermann 1969, Marine Biology. SidgWick and Jackson, Ltd. London • Gotto, R. v. 1969, Marine Animals. American Elsevier Publishing Company, Inc. New York, N. Y. • Martin, John Holland 1979, Bioaccumulation of Heavy Metalsby Littoral and Pelagic Organisms. u. s. Environmental Protection Agency. Narrangansett, R. I • Moore, Hillary B. 1958 Marine Ecology. John Wiley & Sons, Inc. New York • Sumich, James L. 1980, An Introduction to the Biology of MarineLife. Wm. c. Brown Publishers, Dubuque, Iowa Sverdrup, H. v. 1942, The Oceans; their Physics, Chemistry, • and General Biology. Prentice-Hall Inc. Englewood Cliffs, N. J. Christy, F. T. 1979, Canadian Journal of the Fisheries• • • • solar radiation Web of Interaction .--~~~~~~~~~~~~~~~.--. 1 . I ' ~ L. 1 Man _ -· · ··· ·· · · --~ .....__ __ r-·---,.i,rzt'--,"7.i1\--'l'. -- r:.-- , ,-- .. --- ·-\f , ,~itf._..., l ' l ! ) j I i .. c1~---J..-. . I . --r --] J' / I I i [baLen.J . [:~a~ttion · l whales po u 1 I ·-:_ ··rJ / ' J I ' i /" I I I L1:'.'tit11~~--__ _! I ! ;. --I __l!____ ·-----~ I i . \rppe-r--, I[ I ~ ;I I currentsf~~ r.ur~idi~y I cmHtmest ----i: -· -·-r:.-1J . iet .iower L carnivores L [~~~~~~t;y·· :-l-., l ;~~pl~~·~~ .. .. w I u LrnMt~iri!] I I I I ~g~;;;;~;;:::~. 1· rt~~---cnuEr:i:.ent .rePiEID.iShm~-;;-tl 4;....... ._ ~ ·-- · lI .. -.. _a!1_-~~g -....·~·-·~---I I ----~~~~?~i~<:_~cy~-~ l I \ ii.1k . .- ----- ---__ >jl__ ---~. ----·.. · --~h;toplankton j (primary producers) ~ ;·, ,_ .,._-. . •• _,, ,. a ·.0.....-., ., .., • .,,,....... • ' _ _..._ _ ••• -v . . .........t" ""· ""•'~..,-...,,,.,.. -.....--·-·,.......... o.~···'="'·-~---· jJ 6' ...c:.. • • 12. Contrasting Chemical, Biological, Geological, and Physical Parameters of Polar Marine Ecosystems Jonathan Dunn, Mark Kasmarek • I. Introduction II. Part A: The Antarctic Marine Ecosystem • A. Currents B. Water Masses c. Ice D. Light E. Nutrients F. Primary Productivity • G . Phytoplankton H. Zooplankton I. Krill J. Benthic Waters and Geology K. Pelagic Waters L . Cold Water Adaptation • II I. Bibliography (Part I) IV. Part B: The Arctic Marine Ecosystem A. Physical Parameters B. Biologic Parameters • c . Nitrogen Cycle v . Bibliography (Part I I) • • • • 12 . CINI'RJ.\STING CHEMICAL, BIOLOOICAL, GFDIOOICAL, AND PHYSICAL PARAMETERS OF POIAR MARINE EXmYSTEMS • Jonathan Dunn, Mark KasmarekIntroduction The term bipolarity has long been in use to indicate the presence of supposedly identical animals in the higher latitudes of both hemispheres and their a~rent absence from • intervening te:nperate and tropical waters. Three hypotheses have been formulated to explain bipolarity: "{l) Bipolar animals are relics of a previous cosnnpolitan fauna, the tropical portion of wnich is row extinct; (2) Animals have migrated through cold, deep water; (3) Parallel developnent of bipolar forms." {Powell, 1951} Furthermore, it has been suggested e in several places that periods of glaciation in the Pleistocene could have brought the coldwater faunas of both hemispheres sufficiently close together to allow a IOC>re efficient interchange of species than occurs at present. Similarities in fauna! distribution probably only result fran incorcplete knCMledge of the past. However, it has been noted that similar dis-e tributions of stenothermic animals are indeed present at rroderate depths in both polar regions. A good example in this case is the distribution of the lt>lluscan genus Aforia. {Powell, 1951} It is relevant to rote here that the present Antarctic fauna is of carparatively recent inmigration, "probably rx:> later than Tertiary times, and that the continuity e of the Americas is arx1 has been the chief colonizing route." (Powell, 1951} To show wnether or rx:>t the conditions of bipolarity do exist is rx>t the ulterior pur pose of this paper. The objective here is to condense vast annunt of information ooncer ning the marire ecosystems of the Arctic and Antarctic in order to illustrate im an effective e way the oontrasts of the polar oceans. The readt' :· should make his own conclusions. After nuch cnntenplation and advice concerning the various possible options of how to compile this paper, we decided that to divide it into two parts would be nost operative and efficient. Part A -The Antartic Marine Ecosystem --is written by John Dunn; Part B e __.;. The Arctic Marine Ecosystem -is written by Kacz. PAR!' A: The Antarctic Marine F.cosystem The Antarctic Ocean is unique in that it is the only great ocean whose east-west extent • is rot interrupted by continents. Its routhern boundary is Antarctica which has ice sheets extending to the water's edge in all but a few places. The Antarctic or Southern Ocean enters into the circulation and exchange patterns of the Atlantic, Pacific, and Indian Oceans• The marine ecosystem described in this paper covers the region of water south of the Antarc • tic convergence which lies between 50° and 60°S latitude and canpletely circumscribes the continent. However, the Antarctic Ocean has been defined as the region south of the Antarc tic Circle lying at 66°S latitude. To assign a fully significant northern boundary is practically impossible. • Currents The crux of the Antarctic marine ecosystem is the hydrology. Intense convective 1 • e currents occur ·throughout the Southern ocean; the circumpolar current is a great oceanic gyre where unobstructed, wirxl-driven water flows around Antarctica at the rate of 200 million ft3/seca These currents are caused generally by density changes in the water, wind action, the Coriolis effect of the earth's rotation, ice formation and evaporation, differing e pressure gradients, and tenperature changes; these currents significantly affect the chemical, biological, and geological conditions of the Antarctic waters. Additionally, the three separate water masses of the Southern ~an also afford boundaries for certain populations of marine organisms, as well as for zones of varying ternperature and salinity. e The alnost circular ootline of the continent, the oontinuous ring of water, and the prevailing westerly wirxls lead to the developnent of easterly current systems over the greater part of the Antarctic Ocean forming the West Wind Drift. Observations of temperature,. salinity, and oxygen distribution have denonstrated the effects of the West Wind e Drift. (Holdgak, 1970) Bottan topography also strongly influences this CXllTlplicated current. Near the Antarctic c:ontinent there is a narrow zone in which easterly winds prevail arxl the water flows westward. The boundary between the eastward and westward current systems marks the Antarctic Divergence. The position of the divergence is variable depending e upon prevailing meteorological conditions. At awroxirnately 50°S latitude, due to current and wioo novements, cold water drifting oorth meets less dense water flowing south and sinks beneath it in a massive, slow, subsurface waterfall called the Antarctic Convergence. The position of the c:onvergence is marked by steep tenperature ~salinity gradients at the e surface as well as by abrupt changes in biota. (Barton, 1980) Many species of flora and fauna foond oo ooe side are rarely seen oo the other. Across the oonvergence oorth the water tenperature ranges from 4°C-8°C in the sumner, and fran 1°C-3°C in the winter. Surface waters inmediately south of the c:onvergence have an average temperature between 3-5°C in e the sumner and l-2°C in the winter. Waters further south drop in temperature to as low as -1°C to -l.9°C. (Barton, 1980) Water Masses The Antarctic surface water is a layer of cold water 100-250 m in thickness lying above e a deeper and nore extensive layer of warm, highly saline water. In the winter, the surface water is practically hooogeneous; in the sumner, due to the sun's radiation and the melting ice, there is a surface stratum which is nuch warmer and less saline than the rest of the layer. • Cbservations have been made that by the second half of April and first half of May all Antarctic water has begun its ax>ling trend. As the surface water loses heat, principally by radiation, it ~sheavier and sinks to mix with the deeper water. This leads to honogeneity. In many sections of the Antarctic Ocean, however, sharp ternperature contrasts in • the surface stratum are still apparent as late as May. This is due to the existence of different currents in the two strata: either there is a southward rrovement at the surface, or the oorthward rrovement is strongest in the cold stratum. (Deacon, 1937} These regions • 2 ~(J)'g with strong current differences in surface strata do not ~honogeneous in the winter. e . Approximate estimations made by Brennecke in 1921 indicate that the Antarctic surface layer is uniform to a depth of 80-150 m in the winter with a salinity of 34.4-35.5 pts/1000 and a tenperature range of -1.8 to -l.9°C near the oontinent. In the sunmer, oonditions are very different. For exanple, to illustrate J:nw shallow a stratum is affected, south of e 60°S, water between 10-40 m deep had an average salinity different of .8 pts/1000 from the waters above and below this layer. These shaply defined surface strata are always found in the surrmer ooar the oontinental margins. In these regions there are usually abundant supplies of fresh water, which because of its low density float above the oolder, highly e saline water in the shallow stratum. In cnrparison, further north where wioos are stronger and seas are rot sheltered by drift ice, the pc:x>rly saline water is IIDre evenly distributed through a deeper stratum. It should also be roted that poorly saline strata do oot readily convect the heat received from solar radition to deeper water. The rising tenperatures in e the surnner irx=rease the stability of the surface stratum and prevent vertical mixing. The extensive dynamics of the surface layer, with the depth of the wind's frictional influence being 60-100 m, and with salinity differences arising in regions of variable evapporation, cause great seasonal variability in primary production and in flora and fauna! e distribution. Beneath the surface layer is a great mass of water characterized by a salinity of slightly above 34.7 pts/1000 am a tenperature average of about 0.5°C. (Deaoon, 1937) This layer is designated as the Antarctic Intermediate (or circumpolar) water. It occurs fran depths • of a few hundred meters to depths greater than 3,000 m. A tercperature maximum is found at 500-600 m and decreases toward the surface and toward the bottom. A salinity maximum occurs fran 700-1,300 m and likewise decreases toward the surface and bottom. The intermediate water is fouoo with little variation around the whole oontinent. (Science in Antarctica, • 1961) The water mass known as the Antarctic bottom-water lies principally in the Weddel Sea with intermittent formations south of the Indian Ocean. The water under the sea ice becomes IIDre dense and sinks by therIIDhaline oonvection. As it sinks, it mixes in a 1:1 ratio with I the adjacent intermediate water; at a depth of 4,000 m it has a tenperature of -0.4°C and a salinity of approximately 34.66 pts/1000. "As the bottom water IIDves northward, both its terrperature am salinity increase by mixing with overlying layers, but its density still remains the greatest of all ocean waters." (Science in Antarctica, 1961) • In the exchange of water in the Antarctic region, the intermediate water which sinks at the Antarctic Convergence and spreads oorthward at intermediate levels, and the Antarctic bottan water which flows northward along the bottom, represent a net loss of water. A balance is then maintained by a replenishment through a southward :novement of upper and lower I deep waters. (Science in Antarctica, 1961) 3 • • Ice The developnent of surface ice has a profound effect on the Antarctic ecosystem. There are marked seasonal aB3 yearly variations in the total area of water subject to freezing. It has been calculated that the units of the ice edge around Antarctica vary between a maxi • mum of 10 million square miles at the erii of winter and a minimum of 1-2 million square • miles in the late SUIIlner. (Holdgate, 1970) It is interesting to note that about 1,400 x 1015 Kcal are spent yearly oo melting this anount of ice, while nore than 3,000 x 1015 Kcal are spent on heating Antarctic waters 1°C. The heat loss of the Southern CCean to the atnDsphere, 33,680 x 1015 Kcal/year, is corcpensated for by the heat ooming from the north with the deep waters. The annual heat infla-1 with the southward iroving deep waters is about 30,200 x 1015 Kcal. Furthernore, the anount of heat expended annually by Antarctic waters on warming arii melting the ice mass drained fran the continent is less than 0.5 percent e of the heat transported into the atm::>sphere. Hence, it can be concluded that the heat discharge fran the continent is insignificant to the water regime of the ocean. (Kort, 1961) Ice formations affect many of the Iflysical properties determining primary productivity. As ice forms, it extracts fresh water fran the sea surface, leaving the water irore saline. e When it melts, obviously, the reverse cx::curs. Ice also reduces the anount of turbulence due to wirii action, restricts gaseous exchange with the atnDsphere, and inhibits light penetration into the sea. (Holdgak, 1970) Light e In extreme oouthern latitudes the alteration between total darkness for half the year arXl continuous daylight for the other half imposes a "seasonal light regime in contrast to the diurnal cycles of lower latitudes." Holdgate relates in Antarctic Ecology that the sunshine duration in Antarctica is greater than in corresponding Arctic latitudes; this com e · bined with the high transparency Of the atrcosphere prOIIOtes a great influx of solar radiation. Light penetration into the water is determined by intensity, angle of incidence, surface reflection up to 50 percent in Antarctica according to El Sayed) , absorption of suspended e particles, arXl by ice formation. In the Antarctic zone, measurements indicate that 21 percent of the i~ident light penetrates through a layer of ice one meter thick. Large gradients in light intensity also exist beneath the ice. This provides for the photosynthesis of epontic microflora. e Nutrients Observations en the distribution of nitrates, phosphates, and silicates show that levels rarely fall bela-1 the maxima of tenperate regions and thus are unlikely to be limiting to phytoplankton growth and developnent. (Holdgate, 1970) The extensive current systems and e powerful upwelling and vertical novements ensure this abundant supply of nutrients. Upwelling also affects the hydrochemistry of the Antarctic waters in that it attracts large anounts 4 • ~70 of biogenetic elements into the trophogenic zone. • Furthermore, a distioct latitudinal zoning associated with the dynamic circulation of the water has been observed in the distribution of oxygen, phosphates, and silicic acid. A relatively uniform distribution of biogenetic substance exists in the entire area between the ooasts of Antarctica and the zone of divergence. The waters between the zones of diver-• gence am convergence are characterized by high concentrations of oxygen, phosphates, and silicic acid. The formation of a :Eflosphate maximum and an oxygen minimum at depths of 500700 m is observed in these waters. (Bogoyaulenskii, 1958) Primary Productivity • A general impression from the work of El Sayed is that basic primary productivity is not exceptionally high on an annual basis. Studies of broad areas indicate a range of values for annual production to be between 16-40 g carbon/m2• (An Evaluation of Antarctic Marine Ecosystem Research, 1981) This is much lower than other comnercially productive regions. • Production is concentrated into ai;:proxi.mately six nonths of the year with two periods of increase, the first in the spring being greater than the secom in the autlmlI'l. (Holdgate, 1970) There is extreme seasonal and geographic variability in primary productivity. This is demonstrated in the tables. It has been i;ninted out that intensive photosynthesis occurs • at the edge of relting ice, and a maximum of photosynthesis occurs in Antarctic surface strata, whereas in the northern hemisphere it ~urs at the 25 m depth. The ice layer with its epontic algae severely limits the available light for photosynthesis in the water column. Hence, the date of ice break-up a00 melting is of critical • importance in cnntrolling the rate of build-up of the standing crop and thus the entire annual production. Holdgate distinguishes two microfloral habitats in sea ice -the "snow" carmunities and the "ice" comnunities. The ice corrmunities form an extensive layer extending through • the uppermost layer of "fluffy" ice to a thickness of 50-100 cm. The groups represented in this layer ioclude diatoms, Chrysophyceans, diooflagellates, and green flagellates. The green flagellates are the most ubiquitous a00 generally dominant of the aforementioned. (Holdgate, 1970) It has been found that this ice flora is markedly shade-adapted and exerts • a significant limiting influence on the planktonic algae by substantially reducing the level of illumination. Phytoplankton Of over 1,000 bottled samples cnllected from 160 stations from depths of up to 200 m, • diatoms constituted over 99 percent of the total number of cells in the samples.. Among them, eight species of Bacillariphyta were identified. The genus Chaetoceros was represented by 17 species, and Rhizosolenia by 12 species. The Pyrrophyta were represented by 17 species, the Chrysophta by two species, and the _xanthophyta by one. (Holdgate, 1970) • The great abundance of phytoplankton in the Southern ~ean is connected with the • 5 ~ll e exceptional richness of the diatom flora. Phytoplankton standing crops vary from 104 cells/ liter in the 0-100 m layer to over 105 cells/liter in areas of "bloaning." It should be noted that north of the Antarctic Divergence the ntunber of diatoms proved to be between 7 x 106 cells/m3; this is ooly ooe-seventh, on the average, of the number south of this zone. 4t The snallest ru.unber of diatoms, between 9 x 104 and 5.7 x 106 cells/m3is characteristic of the waters rnrth of the Antarctic Convergence. Zooplankton From available information it can be seen that Antartic waters have a significantly • greater starrling crop of zooplankton than tropical arrl tenperate regions. Below 100-200 m the mean arrount of offsoore zooplankton is 10-50 ng/m3• Contrasting this are the mean arrounts of zooplankton oo the Antarctic Convergence and Divergence --300 ng/m3 and 80 ng/ m3 respectively. The major CX>nponents of the zooplankton are the Antarctic copepod species • Rhincalanus giggas, calanus propirquus, and Calaooides acutus, constituting 78 percent of the total bianass. (Holdgate, 1970) Krill The above data Cb mt take into account the larger zooplankton, especially adult Euphausia • _superba ("krill"). Holdgate suggested that the average krill bianass could be of the order of 50 ng/m3 concentrated in the top 50 m. Krill concentrations are extremely variable. 'I'\«> types of aggregations have been deduced: (a) patches with horizontal dimensions of several kilometers, and (b) swarms with dimensions up to 100 m. (An Evaluation of Antarctic • Marine Ecosystem Research, 1981) Krill distribution is closely connectecf with a number of envirorurental parameters and with the distribution of its phytoplankton fcxxl. For exanple, krill concentrations are fawn on the periphery of the area of upwelling in the Divergence zone.· The exact locations of krill concentrations depend upon periodic environmental changes• anl trophic factprs. Krill concentrations rarely occur belCM depths of 70-90 m. Densities of 15 Kg/m3 or nere have been encountered in subsurface strata during daylight. Several factors suggest that krill is a principal link in the ccuplex trophic interactions of the Antarctic waters: (a) krill form vast concentrations in pelagic waters; (b)• krill is easily available to those organisms which feed on it; (c) krill has a high caloric content. Whales are the largest consumer of krill. However, krill is also a main fcxxl source for many bottan-living, bathypelagic, pelagic, arrl epipelagic fish. The !CM bianass of benthic organisms as available fcxxl oombined with the snall, shallow• shelf area of the Antarctic may have caused "adaptive variability arrl partial transition of s:>ne bottom-living fishes belonging to families Nototheniidae, Chaenichthyidae, and Bathidraconidae to live in pelagic waters feeing on krill." (Holdgate, 1970) The transition to pelagic waters has caused norphological changes in structure of many species•• In sumnary, there are a number of characteristics which serve to distinguish Antarctic zooplankton. 6 • .;z1~ These are: (a) Alnost corrplete absence of larval forms of bottom dwellers; (b) The surface layers are poor in species but rich in individuals, the number of species iocreasing with depth; (c) In addition to vertical and diurnal migration · exhibited by many species, the dominant species confined to the Antarctic zone perform an annual vertical migration of between 400-600 m. There is also a longi-. tt.Xlinal shift of bianass due to the eastward canponent of surface and deep water masses. (Holdgate, 1970) • Benthic Waters and Geology Benthic regions bel™ the limit of ice abrasion support rich faunas while intertidal flora and fauna are limited to crevice-dwelling species and only seasonal gr~h of diatans and filamentous green algae due to the scouring notion of ice along the shoreline. The Antarctic shelf ranges from 40-150 miles in width with an average depth of 200 m. Large areas of the shelf are covered with coarse, poorly sorted deposits interspersed with boulders arrl gravel transported by icebergs. Because of continental conditions, there are oo river or wirrl-borne organic or ioorganic sediments added to the shelf deposits. In the Mc:Murdo Sound-Ross Sea region, the waters under 200 m have a substrate of volcanic rock, gravel or mixed volcanic gravel and sand while the deeper, undulating shelf from 200-500 m is covered with glacial sediments of silt and scattered, erratic boulders. These shelf deposits generally a:>ntain large arrounts of material of organic origin --formainiferan tests, sponge spicules, bryozoan skeletons, etc. In deep benthic waters, deposits are canposed of detrital and sandstone material, siltstones, and argillaceous muds. (Zhivago, 1959) North of the Antarctic Convergence, biogenetic CCJ1¥)nents begin to predaninate in the sediments. The distribution of sediments can be connected with the physio-qeographic conditions of the overall marine ecosystem, and with these connections paleogeographic reconstructions of the Quaternary and upper Tertiary can be made by core sample analysis. The physical environment of the benthos is a very uniform one. The extreite annual temperature range is cnly O. 7°C annually and the salinity varies only .24 pts/1000. The percentage of saturation of dissolved oxygen averages 69 percent with a range of only 6 percent. Benthic invertebrate genera ioclude Urticioopsis, Lineus, Glyptonotus, Colosseooius, .Limatula, Qphiurolepsis, Qphicantha, Cklonaser, and Diplasterias. OVer 500 invertebrate species occur in the benthos. In the deeper waters echinoderms, polyooid, serputid, and terebellid \\Orms appear. There are also large numbers of foraminifera, tubiculous polychaetes, bryo zoans, sponges, tunicates, and corals. The bulk of the organisms are sessile and feed on plankton and detritus; Porifera, Bryozoa, and Ascidige make up 60-90 percent of the total benthic bianass. (Reid, 1971) In a:>nparison, benthic fauna of the Arctic Ocean is poor. Antarctic assemblages are characterized by a large species diversity with considerable regional variability. Arctic assemblages have a much lower species diversity. Pelagic Waters • e • • • • • • • The pelagic waters of Antarctica a:>ntain many species of dinoflagellates, silicoflagellates, 7 • I. and diatans. Eighty-six species of oototheniformes are well represented; four out of the I I• • • • • • • • • • five families of rototheniformes occur in the Antarctic rone -families Notoghenidae, Har~ pogiferidae, Bathydraconidae, Chaenichthyidae, and Zoarcidae. (Norman, 1938) Planktonic Blue, foraminifera have been recorded in quantities of from .04-8451 specimens per gram. It should Fin, Htmipback, am Sei whales are also abundant in Antarctic pelagic waters. be roted that taken together, the tmexploited whales consume about 150 million tons of plank t01ic crustaceans {primarily krill) per year. Cold Water Adaptation It is recessary to nention Arctic and Antarctic fish are constantly being exposed to water tenperatures below 0°C. Observations show that the blood serum of fish in polar waters has a lower freezing point than the senun of fish mt adapted to the cold. Research on blood serum proteins in species of polar fish indicate that interactions of glycoproteins with cne another create a "biological antifreeze." The antifreeze glycoproteins contain t~ amioo acids alanine anl threonine, anl the sugars galactose and N-actyglactosine. the The serum carpounds This blood crlditive is critical to the survival of fish at -l.85°C. of polar fish with lower molecular weights are responsible for lowering the blood freezing tenperature to -1°C; the antifreeze supplements their effect to -1. 9°C. The IlDSt highly significant characteristic of these active glycoproteins is that the nelting point of blood does oot change as the freezing point is reduced• Bibliography (Part 1) "An Evaluation of Antarctic Marine Ecosystem Research," carmittee to Evaluate Antarctic Marine Ecosystem Research, John H. Steele, Chairman. Washington, D.C.: National Acadeiny Press, 1981• Barton, Robert, The Oceans. I.Dndon: Aldus Books Ltd., 1980. Beklemishev, K.V., "Latitudinal zoning of Antarctic Phytoplankton," Soviet Antarctic Expediticn, Vol. I (1958), tp. 113-114. Bedklemishev, K. v., "Concerning the Phytogeographic Division of the Antarctic Pelagic Region," Soviet Antarctic Expedition, Vol. II (1960), tp. 272-273. Belayev, G. M., "Some Patterns in the Quantitative Distribution of Bottom Fauna in the An tarctic," Soviet Antarctic Expedition, Vol. I (1958) , tp. 119-121. Bogoyaulenskii, A. N., "Distribution of Oxygen, Phosphates and Silicic Acid in Antarctic waters," Soviet Antarctic Expedition, Vol. I (1958), W• 101-102. Deacon, G. E., "Hydrology of the Southern CXean," Discovery Reports, Vol. XY (March 24, 1937, i;p. 3-124. Feeney, Robert E., "A Biological Antifreeze," American Scientist, Vol. 62, No. 6 (November~ember 1974), ~. 712-719. Holdgate, M. w., Antarctic Ecology, Vol. I. London: Academic Press Inc., 1970. Kort, v. G., "Heat Exchange of Antarctic Waters," Soviet Antarctic Expedition, Vol. III 8 • • • • • • • Food Chain Relationships in the Pack Ice Zone (After Fl-Sayed, 1970). • • • • ....... -.....,. ,...,,., I J: I ,......._ _,,..I i ._.._ I - ..,.. I I I _.,,__ ... ""' ·~ ' I I I T ,..,... --IT .MIU • ~· ..._._..>_ - I a .. , --.. ... ..... ~ ,.. "• ... ..........>,• • I ,.I , , , , ..... .. ... ..... ,..,. -·-·----- -·-""· • ............. ...._.. ......'C~:;v,,.;,,,,., ........... ......... --.,·-·-..-----,,.. 0 01 t.0 II 0 I IO a SJ B 0 I 10 e IO •.O •·t t.O 0 I t J • Llflll~ ·1G. 4. DisTn'lrutioa ofcblorophyD •, 14C upcakt, and perccnr lisht paietrabaa at di6tres pths at selected aatioas in the Weddell Sea and the region west of the Alllllaic • ninsula. o · • · · o Chi• (ms/m'); o-o •tC upakt (msC/m' hr); o---o 'o liJht. FIG. 3. Number o( c:dla in 1 Jiii of deposit &om the MICIC a( the ocaa bed. r.indiatc statiima. 'V' hatcliina, 1-2 x lll' cdll/pn. Oblique &Jw!ins, I x 10'-10'; circles., below I x 10'/pn. • _.,_.. .,c_..,,_ ze ,. " " ~ W.:::::~~ · r...........~. t • r··················· . f....................-·..-·-·.--· --. • _.,.., ... Drift ...• "'' ... °'"' - WtoNell he Drlfl ____________* ___________ 0 v 0 ~-----~~~t----- ·~ ---~~_JJ__t------ ....... t t ~ :;.•. 6 ...:{=}:·~·-· =--"' _.l____if_ ··::·:·:.=.:}.=.:·;·:.=.:·=·:.=.:}.=.:}.=.:·;·:.=... • • ·::··:::·::=:·::=:·::::·;:::-_.. 1 ~ ~f~;~f~;~f~@ o----U.. :..:·:::·::: ~ 1----~ ,...._. :·:.=.:·=-:.=.:·=-:.=.:·:·:.=-:·:· ~ ..,....,....... 0 ~ ~:·.~: •••••·.·~: I ······~·:~:·:~ lllOO y--lfl»--~ }~~s~~;.;~~~f~ • \.T .~:·:-;:.~~·:~:.:~ l.--211111--1 ~:.~:·:~:..~·:~:·:~: \ •• •'"•":. '••••• ~ A ••.•••••. ~· ••••• a.,,,..~ hJ..-._ .,.;~\\t\l\\\tl!t\~~·-~---- I ~ N-.w: llelldlnp ... "'· ~.. "'-...-.. _....,. ........·-ol NUplii end n-.uplil """-*" -IO --1-. ao.-: MM,1912. FIGURE l Dcwlopmeat of E,p of£...,,,_. ...... ----~-- r----------------.. ----" ~1u {1961), J;P. 363-366. • Lee, Milton O., Biology of the Antarctic Seas, Vol. I. Balti.nore, Maryland: Garanond/Pr idemark Press, Inc. , 1964. Llano, George A., Biology of the Antarctic Seas, Vols. II and N. Balti.nore: Garanond/ Pridemark Press, Inc., 1965. • Maksim::>v, I. V., "Influence of Antarctic Glacier Discharge on the Hydrological Regime of the Antarctic Ocean," Soviet Antarctic Expedition, Vol. III {1961), pp. 191-193. Malins, Donald c. , Effects of Petrolewn oo Arctic and Subarctic Marine Envi~onments and Organisms, Vol. II. New York: Harcourt, Brace & Jovanovich, 1977. e Norman, J. R., "Coast Fishes, Part III: The Antarctic Zone," Discovery Reports, Vol. XVIII {May 1938)' w. 1-104. Powell, A. w. B., "Antarctic and Subantarctic r.t>llusca: Pelecypoda and Gastropoda," Disoovery Reports, Vol. XXVI {March 25, 1951) , pp. 49-196. e Reid, Joseph L., Antarctic Oceanology, Vol. I. Balti.nore: The Horn-Sharer Conpany, 1971. "Science in Antarctic: Part I and II," Comnittee oo Polar Research. Washington, D.C.: National Academy of Sciences, 1961. Vioogradova, N. G., "Geographical Distribution of Deep Water Bottom Fauna of the Antarctic," • Soviet Antarctic Expedition, Vol. I {1958) , w. 121-122. Zhivago, A. V., and Lisitsyn, A. P., "Bottom Relief and Sediments of the Southern Ocean,"Soviet Antarctic Expedition, Vol. I {1959), w. 102-104. • PARI' B: The Arctic Marine Ecosystem Physical Parameters The Arctic Ocean formed some sixty million years ago in the Paleocene Epoch, and became • an oceanic body due to the creation of the Atlantic Ocean by the tectonic separation of Africa and Europe from North America and South America. This occurrence caused the other oontinents to be also displaced and to assemble in their present oonfiguration. The Arctic Ocean is oorrprised of some 14 ,2106 square kilaneters surrounded by land and is a • thirteenth the size of the Pacific Ocean. Starting at the International Dateline and going clockwise, the land masses are: the extensive continent of Russia, Finland, Norway, and Sweden. Then there is a large open body of water with the Arctic Mid Oceanic Ridge below. The large continent of Greenland is next in order with Ellesmere, Baffin, Victoria Island Conplex • North of canada, and lastly Alaska. The smaller seas that help make up the Arctic Ocean going clockwise fran the International Dateline are: Beaufort Sea {north of North America), Chuckchi Sea {near the Bering Strait), and the Kaptev, Kara, and Barent Seas {between Russia and Scandinavia). These surrounding land masses make the Arctic Ocean an alrcost land locked • basin. Cold Arctic waters cnmnunicate with the North Atlantic over relativel y shallow sills • 9 ~71 • (the Nansen's Rise which is between 1,000-2,000 meters deep). East of Greenland and west of Greenland water flows south across a similar ridge through the David Strait. The North Pacific oomnunication is through the Bering Strait, and is nuch m::>re restricted. Surface water fran the North Atlantic flows into the Arctic area, and bottan flowing cold water • flows out into the North Atlantic and North Pacific. (Washburn, 1980) (See Map I) • The Arctic Ocean is divided into two major zones, each with a depth of greater t han 5,000 meters (16,400 feet), by the Lononosov Ridge which runs from just north of Northwest Greenlarxl through the North Pole area, to the New Siberian Islands off central Siberia. These basins formed by the IDnonosov Ridge bisector are named the Eurasian Basin and the Cana:Han Basin. These t\«> basins are also divided into t\«> parts by secondary ridges that are parallel to the IDnonosov Ridge. In the Eurasian Basin this secondary ridge is a continuation of the Mid Atlantic Ridge and Rift System. In the Canadian Basin, the ridge is • variously koown as the Alpha Rise, Marvin Ridge or Fletcher's Rise (see Map I). The Continental shelves associated with the Eurasian Basin side are broad am extend out as far as 700 kiloneters or nore from the oceans previously mentioned. The ooastal and surface waters of the Arctic Ocean are strongly influenced by drainage fran the surrounding land e masses, the nelting of ice, the influx of North Pacific water of lower salinity than that of the Atlantic Ocean. This results in a layer of oxygen rich water approximately 100-300 meters deep with lowered salinity (below 34 pts/lOOO)and tenperatures below the freezing point. The oolder the water the more oxygen it can carry. Beneath this water is a more e dense layer of Atlantic water ooming from between Greenland and Spitzbergen. This water is slightly warmer (.5°C-l.5°C) and m::>re saline (a~roximately 34 pts/1000). This water forms a stratum which extends ler the water is the nore dense. The formationof new ice also causes the water to be nore saline due to the salts not being able to be part of the ice crystal lattice. In the nonths from April-June a rising water tenperature Iarrl corresporrling decrease in salinity is noted. In June the time of 24 hours of continuous daylight is present and the warmest water of the year is ooted. In July-September thesurface water tenperatures are at a maximum and the density and salinities are at a minimtmt.In October-Novernber the water again decreases in tenperature, and the increase in density ensues. As the surface water becxxnes more dense the underlying waters are displaced upward I by the nore dense surface water. The associated nutrients and organisms are taken to a deeper depth with this change of water bodies in the water column as the surface cools andsinks. This time is also the period of decreasing sunlight as the sun noves past the equator Iarrl :rcoves into the southern hemisphere. This condition accounts for the decreasing productivity of the Arctic Ocean during the winter nonths. The density of Arctic water is alsoaffected by the oorthward surge and flow of the Gulf Stream which flows between Norway and Greenland. (~nnaughey, 1978) e The currents of the Arctic Ocean are cX>mi.nated by the Coriolis Effect which causesOOdies of water in the Northern Hemisphere to flON in a clockwise gyre or motion. Thiswas also c})ctmtented by Nansen's Farm Expedition when their ship was trapped in the ice and had to remain ice-bound until an aw:>rtunity for unbounding could occur {1893-1896). How-Iever, there is also a gigantic eddy oorth of Alaska and west of the Canadian Islands, thatcauses ice 200 miles oorth of Alaska to rrove eastward or oortheast, and then curve arourrl 11 and :rrove south and routhwest along Borden, Prince Patrick, and Bank Islands• • The tides in the Arctic are insignificant and range f ran 18 inches in North Alaska : to 8 ioches in the Coronation Gulf. However, during storm tides a strong southwest or westerly wioo may produce a swell with an arcplitude of five feet. In the wintertime, this • forces ice masses against the shallow and extensive shelf areas where the previously mentioned scouring occurs. (Washburn, 1980) Ice is cne of the main elements of this polar region. It cuts off light into the water column, an:I acts as a barrier between the air and water interface, and decreases availa 1 • bility of Wlter to oxygenate. With a large percentage of the Arctic Ocean ~YJered by ice as in the winter and subsequent density increase, the surface water will go 10\';er in the water column carrying the oxygen and nutrients with it, and thereby decreasing the photo plankton reproduction which is already en the decline due to the absence of sunlight. e (Ostenso, 1966) Biologic Parameters The living organisms in the Arctic Ocean are dependent upon nutrients, sunlight, and the extent of ice cover. "As in any aquatic ecosystem the primary producer's (phytoplankton) ~ ability or n:>n-ability to reproduce has a great effect upon the zooplankton, invertebrates, small fish, and all the way up the food chain to the carnivorous whales and p::>lar bears, which share the top predator slot or niche with man. In the winter nonths (December-March) the phytoplanktcn abundance are at a minimtm and nutrients are at a maximum fran non-consump • tion and subsequent conpilation throughout the winter, which is also oonsistent with the absence of sunlight. Also, since zooplankton are reliant upon the phyt~lankton, the zoo plankton abuooance is likewise at a minimum. In April-May there is a sharp bloan to a maximun of the phytoplankton with an intense hatching of zooplankton following. At this e time there is also an increase in the quantity and intensity of the sunlight as the sun roves into the Northern Hemisphere. A rapid fall in the nutrient level occurs synchrooously due to large consumption by the Iflytoplankton. In June the phytoplankton abuOOance decreases due to the near total consl.Ullption of the limited nutrients. Also in June the zocplankton e abuOOance increases to a maximum. In the surrmer (July-September) light and nutrients decrease to a minimum, and the phytoplankton show a likewise continued decrease except in localized areas where nutrient inp.it fran a land mass or islarxl occurs. If this occurs then there may be a corresponding increase in the z.ooplankton, but overall the phytoplankton e aoo zooplankton show a net decline in abundance. Finally in autumn (C:Ctober-November) the light is at a minimum and the nutrient level starts to increase due to oon-consumption and compilation. Without light the phytoplankton level rapidly decreases, and with it the zooplankton also die off. From winter to spring the types of dominant organisms change. e For exanple, the Decent>er-March interval sees a dying of sumner species (e.g. calanus). The April-May interval will see a blCXJm of protozoa, or a reproduction of calanua and Thysa noessa. In the sunmer rronths the flowing of warm water Atlantic species cx:curs and ca1anus • 12 .;i~o descends to deeper water. In autumn the summer plankton die off and calanus reappear and other halophilic arx3 eurythermal species. (McConnaughey, 1978) (See Table I) With these fluctuations of phytoplankton and 2.00plankton the small fish populations which derive their food fran the zooplankton show a similar abundance or absence. HONever, their ability to be nuch nore nobile and to travel to other waters allows these fish to seek out areas of greater productivity, an3 go into the North Atlantic and North Pacific. In these areas of nore food the water terrperature is still cool, but the presence·of I light arrl the continuation of the food chain allows them to inhabit these areas until sunmer aH;>roaches. (Lucas, 1974) The fauna of the Arctic Ocean have a high percentage of endemic species, rost of which are circunpolar in distribution. Approximately 80 species of fish belonging to 45 genera occur in the Arctic Ocean. Forty-eight of these or 60 percent are restricted to Arctic waters only. Eighteen of the 45 genera or 40 percent are endemic. Some of the rrost important fish are: catostonus catostonus -wng Nosed Sucker Argyrosornus tullibee -Toolaby Leucichthys lucidus -Great Bear Lake Herring Clupea pallasii -California Herring Stenodus mackenzii -Connie Salvelinus malma -Sallron Trout Cristivaner mamavcush -Lake Trout Thyrnallus signifer -Arctic Grayling Usmereus dentex -Arctic Smelt Platichthys stellatus -Starry Flounder Microgadus proximus -Torccod I.Dta maculosa -Ling onc-cx::ottus hexacornis -Six-horned Bull Head (~nnaughey, 1978) The Arctic Fauna is in general poorer in species than the faunas of lower latitudes, but those which are present occur in greater numbers in accordance with the rule that extreme envirorurents where there is enough food will support small numbers of species, but inmense numbers of individuals that are able to exploit the resources. The short Arctic sumner is a season of intense growth and reproduction. Planktonic animals such as calanus have two or three broods in the lower latitudes, but in the Arctic are restricted to just one brood. Also there is a tendency toward individuals to grow to slightly larger size. Unlike the Antarctic Ocean which has an immense land in the central part of the area, the Arctic Ocean hasn't any land mass centrally located. This means the fish and other organisms that need a substrate or other anchored object for egg laying must go to the circumference of the Arctic area to nest or seek shelter. This changes the life strategy of the organisms there. The krill are a shrimp-like crustacean that occurs in immense numbers in the polar oceans, nore so in the Antarctic than the Arctic, but nonetheless are present in the Arctic, 13 I I I I • • • I • • e e e e • 1. • • • e • ;zg I and their presence is determined by the number and availability of the zooplankton. Thesekrill are a major source of food for the baleen ~hales that frequent the Arctic ~anin the surrmer. These whales generally travel with their young in lower latitude waters,but must :nove from the Northern Hemisphere to the Southern Hemisphere to follow the springhatching of focrlstuffs. The krill are also eaten by small and large fish, who make upthe diet of still larger fish and seals. Polar bears feed upon the seals and the seal carcasses in turn support an Arctic White Fox population. The killer whales or Orea feed UIX>J1 seals also, as Cbes the leopard seal. In the deep Arctic basins bacteria and largecarnivorous fish are the main organisms. These organisms must be able to tolerate anenvirorment of cold, darkness, and high pressures that are present in the benthic.Carbon eycle The biogeochemical cycle that is the closest to an actual energy flow through aneoosystem is the carbon cycle. Almost all carbon enters the food chain in the form of carbon dioxide, which passes through photosynthetic parts of autotrophic primary producers.At every stage of the food Chain 002 is released into the water where it can be reused by other phytoplankton or it is incorporated into the sediments by the death of organisms which settle oot to the tottom. ·Some caroon in the sea is oot organically fixed caroon,but occurs as carbonate {CDj2) especially in cam3• This calcium carbonate is used bya host of shell secreting organisms such as pelecypods {clams and oysters), some protozoa, and s::>ire algae. Carbon dioxide reacts with water to form carbonate in the followingreaction: caroonic Bicaroonate carbonate Acid \". ,, -~' The precise anount of each of these oonstituents in the water depends on the Ph ofthe water. Organisms such as Pelecypods can combine bicarbonate or carbonate with calcium disrolved in the water to produce calcium carbonate for their shells. After the organisms' death, the calcium carbonate may either be dissolved or remain in sedimentary form. Many paths which allow carbon to be recycled ensure an adequate supply of carbon. {Clapham, 1973) Nitrogen eycle Nitrogen enters the focxj chain through the roots of autotrophic vascular plants,and through the cell walls of oonvascular autotrophs. Its form is CX)Jl'((Only nitrate {NJj)although amronia {NH3 or NH4) occurs also. In the autotrophic phytoplankton and 7.00planktonnitrogen is incorporated into the organisms' amioo acids, proteins, pigments, nucleic acids, and is passed along through the food chain like any other food source. There is 14 ~82 no loss through respiration, but nitrogen is secreted in the form of animal urine. Nitrogen t is recycled through the detritus food chain, as nitrogenous wastes and/or carrion which is degraded by bacteria and detritus feeding organisms like clams. Certain bacteria, Nitrosononas, can oxidize armonia to nitrite by the reaction: Other bacteria such as Nitrobacter can cxxct>ine nitrite with oxygen to form nitrate by the reaction: • This nitrification allows this bacteria to make their organic materials directly from co2 + H2o. The nitrate can then be taken up by autotrophic phytoplankton at the beginning of the food chain, an:l thus the nitrogen cycle is canplete. {Clapham, 1973) Sulfur Cycle The sulfur cycle has a sed~entary phase that is important to its use. The form \in which it is most cxmnonly fourrl in living tissues is in the sulfhydryl group {-SH) t is renoved from the nolecule as hydrogen sulfide {H2S) by nost deconposing bacteria as the oormal part of the degradation of proteins.. In the aerobic environment of water the H2s is oxidized to sulfate by bacteria specially adapted to perform this conversion: HS + 20~S0~2 + 2H+ • 22 The sulfate produced can then be reused by autotrophs. (Clapham, 1973) Phosphorous Cycle The phosphorous cycle has a strictly sediment-reservoir cycle that is of critical importance. It is found naturally as a soluble ioorganic phosphate ion (P043, HP042, or H2ro4), either as roluble ioorganic phosphate, as soluble organic phosphate, as particulate phosphate, or as a mineral phosphate. The ultimate source of phosphate in the ecosystem is crystalline rocks. With erosion and weathering, phosphate is made available • to living organisms. This is introduced into the autotrophic phytoplankton where it is incorporated into living tissues. In the detritus food chain, as large organic nolecules containing phosphate are degraded, the phosphate is liberated as inorganic ionic phos phate. In this form it is readily taken up by the autotrophs and phytoplankton or is • incorporated into the sediments where it canbines with clay minerals. Therefore, a sedi ment-reservoir biogeochemical cycle such as phosphorous is a rruch nore imperfect cycle than an atnosphere reservoir cycle. The sluggishness of sedimentary phase of the cycle and the great demand for phosphate by a biological cannunity is accorrplished by a rate • of recycling ircrease and mt by releasing phosphate from the sediments where it is stored. This is a major rearon why phosphate is often the nost critical element of an ecosystem. Phosphorous is incorporated into sediments by the following reaction: • 15 • +3 - + Al + H2P04 + 2H2o ( ~ 2H + Al(CE) 2H2P04 Soluble Insoluble (Clapham, 1973) The last biologic and physical parameters have to do with the interaction of light • and the organisms within the euphotic, dysphotic, am aphotic zones. Primary food prcxluction in the marine environment is virtually within the euphotic z.one which is the ill llllli nated surface layers of the ocean, where photosynthetic activity occurs. This occursto approximately 100 meters or nore in the Arctic. Below the euphotic z.one: down to about • 200 meters is the dimly lit dysphotic zone where light is insufficient for plant life.The water below 200 meters is the aphotic zone because little or no light penetrates thisfar. Below the prodoctive surface zone, animals are dependent upon food that sinks throughthe water column from above. Therefore, the deeper they are, the less likely food is • to reach them because the food and nutrients are being deconposed by bacteria and other small and large fish. In general, the deeper the level the less food supply is availableand the fewer the number in the {X)p..tlations. Many planktonic organisms nove ~arer the surface in the darkness and retreat to ~ deep water in the day. Diurnal changes of distribution are shown by a great number of organisms, both plant and animals, plankton and nekton, including medusae, siphoi::X>phores,ctenophores, chaetognaths, pterq;x:x:ls, cq>edpc:rls, cladocerans, arrphipods, musids, euphausids,pelagic decapods, and oome cephalopods and fish. It is row accepted that the Deep Scattering • Layers are caused by echoes returned fran marine creatures which change their depth betweendaylight and darkness. In the Arctic Ocean, the D.S.L. occurs during spring and autumnwhen there are daily alterations of light arXl dark, but the migrations are not observed • when darkness or daylight persists throughout the 24-hour day. (Tait, 1972)The developnent of lower salinity arXl temperature waters stacked on high salinity • and colder water acts as a l:::oundary betw'een two groups of organisms. This therm:x::linestops organisms f ran retreating f ran the sunlight at a certain depth arrl stops organismsof deep water from ascending past the thernocline. Many of these migrating organisms are herbivores grazing en phytoplankton and nove away from the i;ilytoplankton food sourceto escape predators in the light interval of the day. (:Eckman, 1953) • Many species of sponges are endemic to the Polar Seas, but since zoogeographicalcorrparisons are difficult according to experts we \tK>n't really go into sponges. However, • among the Cnidaria the hydroids have several purely Arctic species. Anong Pennatularia,Virgularia glacialis is as Arctic-subarctic shelf species. Sixty percent of West Greenland'sZoantheria arXi Actinaria are entirely Arctic. The bryozoa have 80 endemic species withinthe Arctic-subarctic region. Crustaceans have a large number of purely Arctic species• Arcong the anphipods there are several genera either \\holly or nostly Arctic, Onisimus,Pseudalibrotus, Acanthostephaeia. Considering the isopods, Mesidothea is purely Arctic, with M. entorren living in inland lakes and rivers, and M. megulara being abyssal-Arctic.The gastropods have the Arctic family Buccinidae and the specific genera Buccinum, • , ,. e:< 8 'I and Sipho. Two especially oomron pelecypods are Portlandia artica and Yoldia hyperborea. Echil'Dderrns are numerous with two starfish genera Urasterias and Icasterias with only cne species each. The ophiuroroids are present with 0phiura nodosa and 0phiopleuron borealis, the latter species living in the deep regions of the Norwegian sea. Examples of purely Arctic Holothurians are Myriotrochus rinkii and Ludwigia glacialis. The ascidians have an Arctic genus Rhizonolgula globularis. Arctic fish are present in large numbers and are the Cottidae, Agonidae, Liparididae, Blennidae, Zoarcidae, Anarhichadidae, and Gadidae. The nest important are: Co!:tus quadricorni, Gadus saidi (,IX>lar ood) which is found further oorth than any other fish, Gadus navaga, and Mallotus villosus (capeline). The Polychaetes are present with Nereis pelagica, and Telepus cincinnatus which are both cosnqx>litan in distribution. The Arctic Polychaetes are much weaker than other Polychaetes of the \\Orld. In general it is a c:x:>nnon phenomenon of Arctic boreal species, that they rcostly occur in the upper shelf regions. For example, crustaceans Eupagurus pubescens, and Spriontocaris lilljeborgi live in the upper shelf, but in the terrperate zones live in much deeper water. The starfish Pontaster tenuipinus, which in the Arctic is found as far up as 60-70 meters in depth, and in the boreal regions it is usually does rot ascend past 200 meters. The brittle star ()phiacantha bidentata which in high-Arctic regions ascends up to 5 meters in depth, arrl in low-Arctic regions ascerrls up to 23-30 meters, but in the boreal region ascends to 200 meters and in the Atlantic is only in the abyssal zone. Arctic animals exhibit differences in tolerances of temperatures or therm:>pathy. It is possible to distinguish between high-Arctic species which only live in the cnldest water, and low-Arctic species which prefer regions near the subarctic mixing zone, and the pan-Arctic species which inhabit both areas. High-Arctic species are nostly restricted to negative temperatures and possibly up to 4°C depending upon food supply and availability. As \\Ould be expeted the pan-Arctic species are the dominant types. Some examples are of high-Arctic are: the prawn Sclerocrangon ferox, the amphipod Psudalis birulai, the isopod Mesidothea sibirica, the sea-cucumber Ludwigia glacialis, the nussel Portlandia artica, the starfish Asterias lincki, and Poraniatorpha tumida. Low-Arctic species are poorer in endemic species than high-Arctic species. The organisms which represent low-Arctic species are: the capelin Mallotus villosus, the sea cucumber Chirdata laevis. (Van Der Spoel, 1979) In none of the larger zcngeographical regions of the oceans are the ecological conditions so narrowly restricted as in the Arctic and Antarctic regions. The recent decade has seen a shift rnrthward of the boundaries between the Arctic, subarctic, and boreal regions with respect to the range of cold water species. This is greatly noticed in the Atlantic-Arctic regions. An increase in air terrperature and water temperature have allowed a considerable number of boreal species to extend their highest latitude range also. t t 1 I t • t t t t 17 • • In March, April and May, the critical layer, which is the tody or layer of water where phytoplankton and rooplankton ooexist, increases its depth position. This depth depeoos on the penetration of sunlight below the surface; it is at a maximum in early surrmer and at a minimum in early winter. Until a thernocline is formed by warming of • the water at the surface, phytoplankton are transported below the critical depth, and no effective production can occur. As sunlight becomes stronger, the critical depth may exteoo to the bottan in shallCM areas, but in deeper waters, a thermocline may form at or above the critical depth. In either case, the phytoplankton population exparlds rapidly • as &X>n as the critical depth exceeds the depth of the mixed surface layer. The phytoplankton are three types: Diatanaceae, Coccolithophoridae, and Dinoflagellatae. The zooplankton are of two types: Nauplii and Copepoda. (Dunbar, 1975) (See Chart I) The last aspect to consider is the importance of the Arctic Q:ean to mankind. The• polar areas are critical regions for the study of radio comnunications and solar-terres tial physics. Our radio conmunications that are necessary for national defense can be drastically affected by charged particles that are emitted during solar flares, and are responsible for magnetic storms. Arrl if magnetospheric events such as auroras can be • understood, they may provide clues to other plasma phenomena. The polar areas are the best place to study this activity. Since ~ are also increasing the anount of m2 in the atnosphere by burning hydrocarbons, this could possibly be raising the temperature of the Earth which could initiate• polar nelting and give an increase of sea level. This additional water \\Ould cause a transgression of sea water onto the !CM levels of the coastline causing widespread flooding throughout the WJrld. A well-planned polar nonitoring system could give the scientist a greater understanding of the polar areas am their interrelationship to the physical• aspects of the Earth. The Arctic Ocean is of interest strategically, because the nuclear sut:ma.rines are capable of operating beneath the protection of the Arctic ice, am thereby giving surprise tactics of attack. We need thorough oceanographic data to facilitate or detect such operations. (Clapham, 1973) ~other widespread information and subjects• are: Whale pc>pJlations, adaptations of fish to freezing water, mineral resources, ice novement, icebergs for fresh water source, permafrost information, drilling cores in ice and sediments for historical information of Earth, structure of le the lithosphere, arctic flora and fauna ecosystem knowledge for possible harvesting. (Washburn, 1980) • Man lives in a tiny portion of the total oolar system, and share it with many other organisms spread through many interconnected ecosystems. We know much atx>ut how natural ecosystens q;>erate and interconnect. We also know that the fitness of many ecosystems is deteriorating. The fish-kills, the bird deaths, the increasing algal blooms, the replacenent of high-quality fish by coarse fish, are all analogous to the death of the canaries that coal miners take into their mines to detect bad air. But the miner can • get oot of the mine. Man cannot leave the biosphere. • I t ----4 ....... .._ ..... \.) \.) ~ i-\ ~ ~ ~ ~ "' ~ :t: ""' ~ ...... ~ ~ t--~ u:: I-~ ~ j..... <::) ct." ~ ~ ~ "' ~ \\ii: 4 ~ ~ ""' -J ~~ < ~ Cl!(. "' ~ ~ ~~....a ~~ '1:: ...J I~ ~ c;i:: ~ 0 \N ~ .+ \N -.... ~ ~ -! :t: q,(, ~~~ \N ~~ /-\ v 0 '-...,..) V) (?} 0 '-"' ~ ~ ')--D "' ~ -l · :3 ~~ -..b ~ ~~ t> ~ ~ :t: -..J TN cc:°"' ~~ ~ ""' CL -.J • 0 ...J \,,)..) H Q_ ~ rAbL z. I -Lr~om fAc..LONf'IALJ1:Hz.rJ tf\A P r· . Spring Property Dec.· March ---. ------·---Summer Autumn Winier April-May June July-Sept. Oct.-Now. i .~·:-•:r_ :·.· S11rfa<·c tcmp•:raMinimum 1.,l\ti.' ri"iil1J! Risini: -~:=-=~---·~'· t tun:" nf v. ;Her Maximum Dccrcaloom Decrease ~B!. °"""~ory ~$fVlltNA~A'> Local second R;1pid decrcas•'"" Nearly balanced Consumption _:.~. . ~..........---· zooplankton 'han~c• in Dyin11 of sum-Rloomor ( Strona develFloweri111 or Die-off' or .--,' Arctic ·.--~AUA1to• 1 ~..,. . 1..·har ;i'"·h.'1 of mer spc\'.it.•s \ zoorlankton Protozoa; opment of warmwaler §Urnmer 0 Winter Ca/<11111.r, reprnduction Ca/anus Atlantic ~pp. plankton "·"'\.,:;:" etc. orcalcmu.1 e • n r·· ' ·-·~' ~--~ and Thy-Ca/anus deReappearance ',, • NOUH ,__,,.~,. -.!.., anti 1'hy scends to Calanu. r .. ~ -; 0 • IJp1 [ Iii ~, H • \T ('O CJ I.. f... ; -..:J M1jor Rese1rch C.nler ECJ ~ • R~9ion1I or institution1I center ~ e L1r9' fieldc,nt•r 0. • Othtr t.eldc.nttr s:: e M1n0t rHtarc:ti Ultion ~ ~ ~ .-! lfl ~ ~ I 0"'z _ · l _ __.l....____J O 400 BOO l1lomettt1 0 200 400 natvft ""'" --___l ~ • 4' "'1 0 g Tlioud"llft ol ftlOPllhktm-"' -.UP1 _, lsurf2ce 10 tOO rT!t'ttrt dtllthl G ( F~om W~JHfiUf.11; !1'30) .RJ00-J Bibliography I (Part 2) Angel, Martin, and Tequyn Harris. Animals of the Ocean: The Ecology of Marine Life. Published by Two Continents Publishing Conpany. New York, New York (1977), pp. 100-111. Barnes, Harold. Oceanography and Marine Biology. Annual Review, Volume 2. Published • by George Allen am Unwin Brothers Ltd. (1968), Woking & London. Printed in Great Britain, i:p. 148-163. Clapham, W. B. Jr. Nature Ecosystems. Published by case-western University. The Macmillan Conpany Ltd. (1973), London, England, pp. 54-63. Dietrich, Gunter. General Oceanography: An Introduction. Published by Interscience,A Division of John Wiley &Sons, New York, New York (1963), pp. 114-121. Dunbar, M. J. and D. J. Crisp. Productivity of World Ecosystems. _Proceedings of a Symposium. Published by National Academy of Sciences, washington, D.C. (1975), pp. • 152-175. Dyson, John. The Hot Arctic. Published by Little, Brown & Corrpany, Boston and Toronto(1979), pp. 96-108. Ekman, Sven. Zoogeography of the Sea. Published by Sidgwick and Jackson, Ltd. London, IEngland (1953), pp. 143-161. Gross, M. G. Oceanography: A View of the Earth. Chesapeake Bay Institute. Published by The Johns Hopkins University (1977), Prentice Hall, Inc., Englewood Cliffs, New Jersey. Huxley, Anthony. Standard Encyclopedia of the World's ~eans and Islands. Published • by N. V. Drukkerji, Koch &Knuttel, Gouda, Netherlands (1962), pp. 140-159. Lucas, Joseph, and Susan Hayes. Frontiers of Life: Animals of f.t>untains and Poles. Published by Ibubleday &Company Inc., Garden City, New York (1974), pp. 90-125. McConnaughey, B. H. Introduction to Marine Biology. Published by c. v. Mashby Co. (1978)pp. 153-175. Ostenoo, N. A. Problems of Arctic and Antarctic. Collection of Articles, No. 11. Published by The Arctic Institute of North America (1966), Geophysical and Polar ResearchCenter~ University of Wisconsin. t Tait, R. v. Elements of Marine Ecology: An Introductory Course. Published by Springerand Verlag, New York, New York (1972). Van Der Spoel, s., and A. ·c. Pierrot. Zoogeography and Diversity of Plankton. Publishedby Bunge Scientific (1979), Halsted Press, New York, New YOrk. t Washburn, A. L. Focus oo Polar Research. Volume 209, No. 4457. Published by Science1980 (1980), pp. 643-652. • 19 t • 13. The Gulf of Mexico as a Regional Ecosystem • JIM KARABAICMarine EcosystemsMns. J54RDr. Op,tJenheimer Fall, 1981 • Outline for research on the Gulf of Mexico as a regional-ecosYsteffi: ~ I Abstract II Introduction • a.Definition of an ecosystem.b.Definition of a gulf, characteristics of a gulf as opposed to other systems. c.Concise overview of what the ~aver will cover, III Physical Aspects of the gulf • a. Geographic location, size, origins and age,definition of geogra~hic boundaries used inthis paper. b. Detail of geomor~hologic features, shown incontour, and discussion of their effect ontides, currents, and temperature. • I~ c. Discussion of surrounding land areas and their ·effect on the gulf: for example; terrigenousinflux from rivers and the fate of these sediments. IV Chemical Aspects a. Nutrient distribution as a function of terrigenousinput and ocean circulation. b. Chemistry of the seawater in the gulr, emphasizing the differences between the gulf and the rest ofthe world seawater. • V Biological Aspects (since the area in question is so large, this willbe summarized by discussing productivity as aframework for the biological diversity of the gulf.) • * a. Nearshore productivity -U.S. coastline. b. Productivity of the Desoto Canyon/Mississippi •rrough• c. Productivity of the Cam~eche Bank. d. Productivity of the Sigsbee Abyssal Plain. *note-a-d above will each follow a discussionbeggining with sunlight and :rrimary productivity .,.,,..., and ending with man and his effects on thevarious geographic areas of the gulf. • VI Reserved for additional aspects of the gulf thatturn up in the course of research ; the answers tothese questions may be incoryorated into variousparts of the paper: ~}' Jim Karabaic Mns. 354R a~ Why is the gulf so productive? b. Why is there so much hydrocarbon stored beneath the gulf, is this process still going on, and what is the significance to the ecosystem? c. What impacts has mans• extensive development and use of the gulf had (pro and con) on the ecosystem? d. Do major hurricanes imr,act the ecosystem significantlyr~ VII Summary and Conclusions • • • • • • • • • 13. The Gulf of Mexico as a Regional Ecosystem Jim Karabaic • I In attep:pting to describe an area as vast as the Gulf of Mexico in terms of a regional ecosystem it • • is necessary to talk briefly about many aspects of the region including the geology, physical and chemical aspects, biology, and finally the influence of manQ Therefore, I will attempt to give a rather broad insight into some of these aspects of the Gulf • ecosystem, with a concentration on the biologic diversity, and in the interest of brevity I will approach the subject in terms of processes and gen • eral trends, avoiding lengthy faunal lists or chem-ical descriptions. General Geology • The Gulf of Mexico originated during early Jurassic time, about ISO m.y.b.po , and became stable geologically • by the end of the Jurassic. It formed not as a result of tectonic rifting, but through a process of major faulting streching and oceanization of crustal material (Hanson I98I) • The basin is bounded by the north american craton to the north, west, and southwest, on the east by the carbonate . -~ bank of the Florida-Bahamas platform, on the southeast • .~. 2 • by Cuba, and on the south by the Yucatan--Campeche carbonate bank. It can be described as a semi-enclosed basin, with a surface area of approximately • I,540,000 square kilometerso To the north and east the continental shelf makes up 22% of the Gulf area and • is covered by water less than 600 feet deep. Circulation here is greatly affected by wind. The continental slope covers another 20% of the area, and ranges in depth • between ISO and 3,000 meterso The .Sigsbee plains in the west and southwest and the Florida plains in the east make up the rest of the area of the Gulf (genarally • speaking), and reach a maximum depth of 4,000 meters or • :;.;i.nd de.posi.tiono further o _::~< .-__:;·_~ -; silt i:; the most dominant form of deposition, and in the centrc-..1 gulf globigerina (carbonaceous) ooze i s t~1c most prevalent form • of deposition. Carbonate bar..lcG a:cc fv~:i·,,J. ;_n Lh~ e~st and • ..,('•J-1 '!"" C"J-·i:-r. "'···--;-I '] 1".'1 - '\cs l.~ ·i-~c·-. ._, , _ . ••.l...._ .L'-· Cl.J...1 -~'-~ ._,._ .L .. e The l·Iissi.sc Lpp-l . .. -.:::, ,E. _ .... , P'"_••.... _ _. :_ _,_ ..-__...--:• .-i' •' ~. -¥ ""~ ' I ("'ria-~ ' 'C -----{..-,. -~-• •·----..... ,:..&, .. • ">:a.:;:d ,Jm.v-:1 a] ong the Texas coast. Some rivers empty • • • 3 Jtrectly into the gulf (sucl. as the 1'1is3issippi) 7 .:7. . 1.~1 e o"-he,... c of which there are many, enter est '/'.LL ..... I.. 4 ;;.:i' • uaries and mix with ocean water the.re. General phemistry T:1e average Galinity of ocean water in usually • • close to 36 parts per thousand (ppt), and the Gulf of l11lexico is fairly representative of ocean water in general, having salinity ranges from 30.6 ppt to 37 ppt• Concentrations of pxygen in the more central part of the gulf and the loop current (the loop current is • a result of funneling of water through the eastern straits of the gulf), have been shown to be approx. 4.-Scc per liter of seawater at the surface. These values • increase slightly with depth, then decrease to about 2.35cc per liter at 300 meters depth. This layer of • mininn.un oxygen is and has been important in the presrvation of organic matter associated with hydrocarbon deposition. Oxygen values increase again beyond • this depth to about 5.0cc per liter at 2,40o+ meters. _Phosphorous :ts associated with influx from rivers and.,.--... is most prominent just beyond the Mississippi delta, decreasing seaward. (This is ~example, using the major river system.) • • 4 • The range of concentration of phosphorous in seawater in the gulf is roughly 058~-atoms/liter at the mouth of the :Mississippi to .I4 ~/liter in the central gulf. Trace metal concentrations are measured in parts per billion (ppb) and were found to • be as high as IOX that of avcJ:age seawater, aga1n due to heavy i.nflux of rivers into the gulfo Data for Nitrate-Nitrite concentrations was not researched • extensively, but it is known that nitrate concentrations increase with depth in the Yucatan channel, because the deeper waters are of Antarctic origin. (Antarctic • intermediate water.) General Biological Characteristics Salt Marshes are important on the gulf coast and tend to develop on coasts of very low energy and shallow slopeo They are best developed along the more protected shores of the northern gulf, and Louisiana has almost ~ the total calt marsh acreage in the u.s. Salt marshes are the site of large Quantities of organic matter and provide a habitat for a large number of animals and other plants~ ,, ,,,,,...., They are also a buffer zone between the land and sea in that they provide protection from erosion, salt spray, and drifting debriso • • 5 Seagrasses are flowering plants that grow completely submerged in seawater, and they play an important rol e in • the ecology of the gulf. It is interesting to note that they originally evolved on land ( they have t rue roots stems and leaves) and became adapted to living in sea • • water. Of the 8 genera in the world, 4 occur in the gulf of Mexico. Seagrasses provide a trap for sedi ments in water depths up to 60 feet and tend to act as a stabilizer for sediments. They have a high rate of carbon fixation, but .-. their main contribution as a food source is in the form • of detritus. They also provide shelter for the young of many animals. They are most prevalent in the gulf from the western coast of Florida to the mouth of the Miss • • issippi river, and the westward drift of the Mississippi discharge l imits their occurence westward. 1hey occur in the gulf, not: in estuaries where the environment :Ls harzh. Tl"' ere i s a great deal of l'lork oeing dcne L.1 t~1c area of r:lay-a . • t "·· r .-.·11-r .c ,f '-· I..;:) .__•__,_ . l~J8.ngrovcs pr o-r,dde a unique trans:Ltio~ zone bet~reen t he .,..,,,...... • • 6 • along the southwestern shores of Florida, becoming s1naller and· more scarce along the northern gulf coast, at which point there is a transition and the seagrasses • become more prevalent. It is interesting to note that the flowers of some species of mangroves produce ab undant nectar that is used by bees to make excellent • honey. Phxtoplankton are distributed in for basic areas • throughout the gulf; estuarine, estuarine-coastal, coastal-open gulf, and open gulf. The maxirm.un production of phytoplankton is in the spring and summero • Diatoms dominate the inshore coastal areas, whereas dinoflagellates dominate in open gulf waters. Areas of • upwelling (Loop current and western Florida) and river drainage (Northern Gulf as well as western Gulf) are the most productive areas, while the open gulf is the • least productive. As previous reports have indicated, phytoplankton are responsible for red tides, and the relatively more frequent occurence of this phenomenon • in the gulf calls for a little more detail on the subject. The planktonic dinoflagellate Gymnodinium breve has been • isolated as the " causative agent " in the occurence of • • • • • • • ~ • • • • • the red tide in the Gulf of Mexico. This species blooms annually, but many interrelated conditions must be in just the right balance for a major outbreak to occur. Fluctuation of nutrien~ as a function of river runoff is a major factor, and recent studies indicate that the prescence of Fe concentrations are of special importance. Research is being done in this area in the hope that predictions of major outbreaks may be possible, perhaps through intensive monitoring of river runoff. The dinoflagellates produce a neurotoxin, which, in high concentrations, can paralize and kill fish, but does relatively little harm to invertebrates. The first documented red tide occurred in 1844 and since then there have been 24 outbreaks in the Gulf of Mexico. Normal blooms will produce about IOO cells per liter of seawater, but during a major bloom the concentr~tions can get as high as 75 million cells/li.ter. J""';.1_ere have been. no humar: f~.tP.lities repc,rted in conne.ction v:~t.h thE: red -:itc , but if people eat fish that has been exposed they become ill a•d experience a tingling sensation and a loss of coordination• - 8 • • Benthic Algae are present in the gulf in the form of blue-green, red brown, and green algaeo In the eastern and southern gulf their distribution is severely • limited by availability of a suitably rocky substrate. They do not live well on living reef connnunities, but • o they will colonize patches of dead reef In inshore areas around the gulf they tend to be more abundant due to man-made structures such as jetties and seawallso • These organisms are very dependant on the availability of light to carry on photosynthesis, but the exact limits under which they can survive are not well est• ablishedo Benthic algae produce antibiotics which they secrete as a means of inhibiting grazing and parasitic • organisms. If they are seriosly disturbed by, for eaample, a major hurricane they can very quickly rebuild their communities. The sandy, unstable, o.ffshore areas in the • northern and western gulf are not a very good substrate for these algae, though they do very well in the bays behind the sandy barrier islands and on the man-made • structures. There is a diversity of zooplankton in the gulf waters, • and, like phytoplankton the principle regulators of abundance and occurence are upwelling and river runoff. • • • • • • • ·""" • • • • • 9 Copepods probably constitute the majority of the zooplankton in terms of biomass in the gulf waters • The diversity of zooplankton increases with increasing salinities, and the diversity is also greater in the summer than in the winter. This is generally speaking however, and more specifically, zooplankton peak in the northern gulf in the winter becauseof two factors: I. The Mississippi river peaks in the spring and fall, and 2. 'lbe winter months bring cold wind and water to the northern gulf, facilitating mixing and greater blooms of zooplankton. Southern and eastern gulf zooplankton , on the other hand, experience prominent summer blooms as a result of greater upwelling effects of the "loop current" during the sumner months. The general biomass of zooplankton in the gulf is greatestin the estuarine environment, less in the shelf environment, and least in the open gulf waters. The ''loop current" mentioned earlier is geographically defined as a function of the occurence and abundance of copepods, pteropods, forams, and planktonic shrimp. So, the major occurences of zooplankton are associated with the loop current, the upwelling off the western coast of Florida, Mississippi river runoff, and Texas river runoff {which is in general lower in volume but still high in nutrients.) . IO The fishes of the gulf and of the northern gulf in particular have been described as a warmtemperature fauna and is relatively rich in comparison to the world oceans. There is a greater diversity of species in the northeastern gulf than in the northwestern gulf, and this is attributed t o a number of tropical species found in the eastern gulf The species a are probably ecologically dependant on the coral-sponge bottom communities bordering the west coast of Florida. The shelf fauna of the northern gulf is richer than that of the southern gulf and it is believed that about IO% of the species of the northern gulf are endemic, that is, they evolved there (relatively recently geologicaly) and subsequently remained thereo There is,however , a major fishing industry to the south off the Campeche Bank area.. Some of the main fishes which constitute the :_:tnl~ between t~ "C r'.lacroplankton ( pianl<:tonic sn:rimp) &nd t ne preaaceous fi~nes ttre tue a.ncnovy. rw.1...Le t: , croa.tcer, t:;anm:rou-c, groupers, ana rea ::;nappers. Tne J.1t>t: J..s a J..Ong one, OUt l.t ~lS J.mportant to re111enwer tlH:tt: t:ne mctjorit:y oi tnc bi.om.ass occurs at t ne eages o:t t:ne i::>.an.Ks <11.scussea ecff:_l.er,m1Q at tne 8J~te8 or ·Gpwe.c.ti.ng ttnc. river rv.no1:r, .. • • • • • • • • • ·• • • Ii It 1.8 interesting to note tn~t young snrimp cae res.red in siuuLow marsnes, ana tne o.taer shrimp • live on the nnid bottoms, especially on either s i de of the Mississippi delta. It has been thought in the I past that these bottom fisheries were incapable of 1. • any great expansion. It is now believed that if salinities can be controlled in inner bays then they may prove to be more suitable for shrimp cultivationo Another possible boost for the shrimp would be a greater exploitation of the pelagic fishes 'Which feed on - • ••~ them. In either case the trend seems to be a further control and intervention by man instead of " leaving things alonen and this seems to be the correct approach • to the ecosystemo Man is irreversibly involved and further scientific work seems the only logical approach to overcoming recent problems in the ecosystem. The gulf of Mexico is perhaps one of the most exploited and im~ pacted ecosystems in the world, and only more technology, • • not less, can preserve ito It should be noted that the fish of the abyssal plain in the gulf are not well known. For the world ocean only 7I species of fish have been taken from such depths. The fact that the deep gulf is • I2 • • well separated from deep areas in the Caribbean and the Atlantic would inicate that many of its' fishes might be distinct species. • The main representatives of the manunals in the gulf of Mexico are the cetaceans or whales and dolphins. The • dolphins are represented mainly by two species, the bottlenose dolphin and the spotted dolphin. 'llle cetaceans are all carnivores of one kind or another, I some fee .; ... ~;-4.. C~.4.-=· 1 i;..zec1:...> -c··ou, ' .......l.i,trv-./ in--the • • •• .l • • to the proble.m. \!ill shm/ little that are not i2,9j)'illar1y 1J.nderstoo-3 , ~:~~c~s::crc Jove:rm:1cntal r:; 80. s se.r::::ns t o be j_n t~1e Oj;.•posite directi on" It i s ).mpo:rtaut ·to ~~11£..ce ir:. 1.::.-erspecti:ve tL.e E.mount of time the GP-lf has been evolving (a~)proximately 190 million yea.rs) compared to tb.e arr.taunt of time it has undergone extensive industri&l impact ( approximately 80 years) when considering hm·r certain· we can be of the ultimate impact of cur int.... erven.tion.. Hy general impression is that ultimately the gulf will be completely explored~ exploited,altered, and molded by man through his technology to suit his needs, and that t his is not inherently bad as long as it is biologically soundo • t ~10 bottom 1-ine (i"f vou '11 P .'"'·.,,..;·1o-)..• tl~1e i"--.-r-o.....-,... ] i·tir) J -, u.i...... , 1..t.1_ !. l:u:.t.-.J i~~oc that man is deeply involved :i.n t be ecosystem, and always • To bury our heads and turn from the situation ls the worst course of action. De relopmcnt -::vill co11ti'rt1e in • • • • • • • • • • • • • • • • • .,....,,, • 5740923 GI39g Geol. Lo 5740923 G952g Geol Lib'y I5 BIBLIOGRAPHY (Hansen I98i) Lecture notes from Geology 32I (Stratigraphy) for the fall semester• (Galtsoff, Paul I954) Gulf o~ Mexico, Its Origin, Waters, and Marine Life. Fishery Bulletin of the Fish and Wildlife Service, Volume 55, 1954• Gulf Universities Research Corporationo Gulf of Mexicoo Publication number 109 April, 1969 o The state university system of Florida, Institute of oceanography. A summarl 2£. knowle5fge of the eastern gulf of mexico. 1973• (Lehner,1969) A.A.P.G. Volume 39,1969 (Used this for overhead on basinal cross section) 3DlP • • • 14. Mediterranean and Black Seas: Outline Jody Cadenhead and Brenda Kirkland I. Introduciton-history, recent and geologic, definition of system parameters II. Mediterranean: Physical Aspects A. Geography: location, basins, islands, coastline B. Shelf C. Sediments D. Rivers E. Water balance: climate, evaporation/precipitation(Neg, water balance) salinity, current flow F. Tides G. Nutrients H. Temperatures III. Mediterranean: Biological Aspects A. Producers: effects of pollutbn, Aswan High Dam B. Consumers: economically important fish, over...-fishing IV. Black Sea: Physical Aspects A. Geography B. Shelf C. Sediments D. Rivers E. Water Balance F. Nutrients G. Tides H. Temperatures V. Black Sea: Biological Aspects A. Introduction B. Producers: algae, phytoplankton, anerobic bacteria C. Consumers: zooplankton, bentos, fish D. Sea of Azov E. Conclusion Jody Cadenhead Brenda Kirkland 3ol• December 14,1981 14. THE MEDITERRANEAN SEA, BLACK SEA, AND SEA OF AZOV: MARINE ECOSYSTEMS • INTRODUCTION "Mediterranean", the word itself is derived from Latin and implies a sea in the middle of land. The Mediterranean and Black • Seas are surrounded by the lands where western civilization, and the science of oceanography, were born. From these seas, in the 4th century B.C., Aristotle described 180 species of marine animals • in the Mediterranean (Idyll, 1970), and took d~pth-soundings in the Black Sea (Emery and Hunt, 1974). The Mediterranean and Black Seas are relict seas, remnants of • Tethys, a paleo-ocean that once extended from Portugal to Southeast Asia. It ~eparated the nothern continents from the southern ones after the breakup of Gondwanaland (Fairbridge, 1966) . • Both the Mediterranean and Black Seas are landlocked, silled basins. Their geography influences amounts of river runoff, precipitation, evaporation, and reflux of water into the Atlantic • Ocean and Black Sea. All of these factors affect w~ter balance · which, in turn, influences tides, temperature, salinity, nutrient levels, and amounts of dissolved hydrogen sulfide, methane and · • oxygen. Man has inhabited the Mediterranean-Black Sea region for millennia and his impact on the natural ecosystems should be considered. • MEDITERRANEAN: PHYSICAL ASPECTS GEOGRAPHY Surrounded by Europe, Asia Minor and Africa, the Mediterranean • is landlocked except for the Straits of Gibraltar (13 miles wide) which connect it to the Atlantic Ocean, the Bosporous and Dardanelles (1/2 to 2 miles wide) which connect the Mediterranean to the Bl ack -2 • Sea, and finally, the Suez Canal (JOO ft wide, 37 ft deep) which connect it to the Red Sea (Parker, 1980). (See fig . 1 and 2) The Mediterranean is fundamentally divided into eastern and , western basins at the ~trait of Sicily (Bramwell, 1977). The W8stern basin being dominated by broad and generally smooth abyssal plains, is split into three more basins. The Alboran Basin between the coasts of Spain and Morocco, the Algero-Ligurian Basin (or Baleric Sea) between Sardinia and Mallorca, (In this area we find the Baleric Islands and trenches that are more than J,000 ft deep) t . and, lastly, wi thin the western basin of the Mediterranean·, the Tyrrhenian ~asin. found north of the Sicillian Strait between Italy and the islands of Corsica and Sardinia.(FAO Fisheries Report, 1977?). t The eastern Mediterranean, is noted for its so-called "Mediter ranean ridge system." It would probably be better termed the "Medi terranean rise" because it is not a spreading ridge, but a compressed 4 thick sedimentary prism located between Eurasia and Africa (Bramwell, 1977). The crust here is upwarped and complexly fractured. To the east, it is down-faulted and in this area there is a series of dep ressions. The deepest part of the Mediterranean is found here, the Hellenic Trough~which is 5,092 m deep. Because sedimentation can not keep up with tectonic deformation, there are no substaintial t abyssal plains found in the Bastern portion of the Mediterranean. The easter~ Mediterranean, like the western· Mediterranean, is divided into a number of basins ~ The Ionian Basin with a relatively 4 large abyssal plain; the Levantian Bas_in, found between the Ionian Basin and the slope of Asia Minor; theAegeanRegion, surrounded by the isle of Crete, the strait of Dardanelles, Greece and Asia Minor; and finally, the Adriat ic Sea between Italy and Yugoslavia. • -3 3o .,.. 11f1lw suhHopi.-•I \ll•nl..-. anJ m•ny A1l1n1i,·dcmrr,•I Jcmcrul 5f'e a \'CT) lhall"" Jq11h un~·· anJ •« n•rrn,.11• lounJ in shallo,. .-..... ral •r.·,, "h··rr pl,nL10n fi>h 'i"''ics >U< lish m•mh J I•• rro.JU\·l.iclfl I\ ~r"lci.t \, 1h.-... h'h lcnJ lo mu\\· Ji>lrthuh'J 1hrou~h<•UI !hr .... Sonic srcci~\U(h u mullcl. ~l>r.•m. 1.-a b..& 1n4 "'""' 'lhrimp• .,.. ruv. .uJ 1h..· -.h.ill in Ilk· .umnh·r 1n h""J"'""' h• !"'""'""' •nJ I""" ,·,.J "'· ho,.c\cr,n1IJ-••ln J,.,IJ,·r. ,unnn... 10 .h.11.............1...1cn \11ho11"h tlw rd•p• .....a ..t.al Ut'"dhn~ .•h,·ir ri,lh. rh.-. r~nJ '" h..· _,..,."'••uJ Fig. 7 (Bramwell, 1977) ' • • • • • • • • • • • 15. Marginal Seas Michael Murry, Kevin Zonana I. Description II. Continental Influence-Meterology, Geology, I I I. Biology IV. Examples of Marginal Seas A. Bering Sea Ecosystem 1. 2 . 3 . 4 . 5. 6. 7. 8 . 9 . 10. 11. B. The 1. 2. 3 . 4. 5. 6. 7. 8 . Description Meteorology Currents Geology Chemistry Primary Productivity Phytoplankton Icthyofauna a. Commercial Utilization of Bering Sea Icthyofauna Marine Mammals Benthos Summary Red Sea Physiography Climatology Hydrographic Properties Circulation Chemistry The Hot Saline Pools flora and Fauna Some Economic Aspects • • and Chemistry • • • • • • • • V. Conclusion VI. References Michael Murry• Kevin Zonana ,,__ • 15. MARGINAL SEAS • A mar~inal sea can be defined as a relatively shallow marine boay of water bounded by the continents or by the continental shelf with varying degrees ·of restricted circulation• Description Marginal seas are found at all latitudes, in all climates and ac,. count for ·numerous types of ecosystems. rrhey can be placed in one of • three cata?ories based on their geo~raphic associations with continental blocks. 1rhese are 1) Between continental blocks 2) Between continental blocks and island arc systems and 3) In long narrow rift zones formed by breakin~ up of continental blocks • Continental Influence-Meteorology, Geology, and Chemistry All marginal seas are influenced in almost every aspect by the con • ..,-... tinent with which they are associated. Meteorologically,,they are subject to rapid weather fluttuations influenced by complex weather patterns developed over land. Northern seas may freeze in the winter while tropical seas nay have temperatur~s in access of 72°year round. Also in areas of high rainfall freshwater run...off may lead to dilute or low sal inity marine waters. Geological!~ mar~inal seas are influenced by the enormous sediment input from the continents. These sediments accumulate in in the marginal sea basins and may be 2-3 km. thick. River inputs also have an in • fluence on the chemistry of marginal sea ecosystems, supplying nutrients necessary for primary productivity. Some land locked seas, however have little or no river input and are low in primary productivity. Dis • solved oxygen is at or near saturation in most marginal seas due to ver~ tical mixing over continental shelf areas. Biology • Because of the biological variability, in marginal seas few generalities can be made. For the most part, however, they are very productive • environments with some of the world's major fishing grounds. • Examples of Marginal Seas Because there are as many marginal sea ecosystems as there are marginal seas they can be best represented by examples. • Bering Sea Ecosystem A northern-most extension of the Pacific Ocean. the Bering SP.a is a fascinatin~ environment. It is one of the world's most productive environments and is characterized by one of the world's 1argest marine mammal populations, perhaps the world's largest clam population, the world's most extensive eelgrass beds, a lar?"e annual commercial fish yield and one of the world's most productive benthic environments. • Description The Berin~ Sea is bounded by Siberia to the west, Alaska to the east the Chunkai Sea to the north, and the Aleutian Islands tothe south. (Fig.1). It covers an area of 889,JJ4 sq. miles and has a maximum width of 1488 • miles. The mean depth~s 5243 ft. and the maximum depth is 1~501 ft. in the Aleutian Basin. (Fi~.1). The sea was named after Vitus Bering who led two expeditions there in the 18th century (Fairbridge, 1966). • Fig. 1 Map of the Bering Sea "' • • • 0'--1 _ 2...._)>0_ 4_..-z-HO ward flow · combines with the;southward flowing subarctic current (flowint; out of the Otr"i:ic ncea.n) and eventually re-enters the North Pacific Ocen . V'/here these two currents meet in the western part of the sea two large circulatior gyres are formed. The overall efect of the 2 main currents is a cold northern and western sea, and a warm eastern • shelf area. Tide~ are diurnal throughout the Bering Sea and tidal ranges are relativly small. Mean semi-m~nthly ranges areo.5 to 1.5 meters. Tidal currents are of ~reat significance in the Aleutian Islands area. In • passes between th( islands currents reach speeds of 400 cm./sec. and are responsible for transporting nutrient-rich upwelled waters into ("'. the sea. (Hodd and Kelly, 1974) • Geology The large continental shelf area of the Bering Sea is considered to be a submerged part of a continental plate that includes all of North America and ~astern Siberia. The abyssal plain in the central part of the seB is considered to be a northern embayment of the north Paciflc Ocean which was cut off by the formation of the Aleutian Island Arc System. (Hodd and Kelly, 1974) The dominent source of sediment input since the ~esozoic has been the Yukon River. It has supplied approximatly 90% of the sediment input into the sea since that time. Other river systems currently irain,ng into the Bering Sea are the Anadyr River and the Kuskowim River. (Fig.1). "tW ... 111' '"' ~1 Dz CT:J3 ~~~~~e!Z3:h Fm. 411. Bottom soils ofBering Sen (Lisitzin). l Boulders-shingle-gravel; 2 Sands; J Aleurites; 4 Aleuritc day--< 106 m3/scc or 1.2 >< m3/day Nitrqtt output (a) : SJlinity ", .. Temperature C Oiuolvcd 0 ml 'I 1011 ) .1 7 µg-atoms N/liter x 1.2 x m1/day Nitratt input : =0.8 x J0° g-atoms N/day ·'~ ~~ 2 -l 6 ll 2 4 6 8 Surface Advcction (b) • '\ "'! < 20 µg-atoms N/liter x 1.2 x 1011 m1/day SOOm = 2.4 x 10° g-atoms N/day I River runoff (c) S x JO' g-atoms N/day \ I IOOOm Difference (input - output): 1.6 x I 09 g-atoms N/day Primary production : 300 mg C/m1/day ISOOm or 0.0031 g-atoms N/m~-day Sea area: 10 x 1011 m2 2000m I Removal of dissolved inorganic nitrogen by primary production (d): 0.0031 g-atoms N/m1- None Some R1•gular -----·---···---Order CARNIVORA Suborder FISSIPEDIA Polar or ice bear. Ursus mnritimus Phipps x Sea otter. Enhydra lutris Linnaeus x • Suborder PINNIPEDIA Steller sea lion. Eumetopias juhata (Schrcber) x Northern fur seal. Cullorhinus ursinus (Linnaeus) Walrus, Odobenus rosmam< (Linnaeus) Harbor seal. Phoca l'itu/ina Linnaeus x x x• Ringed seal. Phoca hispida S-:hreber Ribbon seal. Phoca fasciata Zimmerman Bearded seal. Erif(nathus harhatus (Erxleben) • Order CETACEA Suborder ODONTOCETI Bottle-nosed whale. Berardius hairdii Stejneger StcJnegcr·s beaked whale. . He.rnplodon iteJ,negcri _Truc x x Goose-beaked whale. Ziphius rnrrrostrlS G . Cuvier x ·sperm whale. Physeter catodon Linnaeus x Killer whale. Orcinus orca (Linnaeus) Dall porpoise. Phocoenoides dal/i (True)_ x ~ Harbor porpoise. Phncoena phoroena (Linnaeus) Nar"'hal, Mnnodon monon•ms Linnaeus Belukha. Dclphmaptcrus lcucas (Pallas) • Suborder MYSTICETI x Bowhead whale. Balarna mr~'.:1'::ils ( e . F • wh a 1 es ) Oemersal fish :.~iscellaneous (e.g. cod, sole) ~............-~ Carnivors -z ~ • Invertebrate car .--~----F-i-sh----~~ . nivo rs (e.g. euphausids) Macrobenthos (e. g, herrine:) (e.g.molluscs PelaFic herbivcrs :V:e iobenthos c=-i/:;_____~ (e, a, copepods) (e.g. copepods) ~ • * Primary pro.! uc tivity 100 .£/\m2/yr. / River Influx -----• Vertical V.ixine: Nutrients Sun's Ener'!y Note: This model has been oversimplified for easy understanding. Also organic material (e.e. dead oreanisms) contribute ~reatly to the nutrient flow, but are not shown con nected in this dia~am to allow easy reading. • • THE REii SEA 331 " ~h. r·· 'ted Sea is a lorn~, narrow basin which separates the African from the Asiatic continent. It extends in almost a straight line from the north-northwest to the south-southeast between JO0 N to • 0 , • 12 30 N latitude. It is about 1900 km long, and its average width is 220 km. A shallow sill at the Strait of Bab-el-Mandeb in the south, snpa-r'ates the Bed SP.a from the Gulf of Aden. The Sinai Pen1nsula • dividP.s the northern· P.xtremi ty into the Gulf of Suez a wl the Gulf of Aqaba.. ThP. average depth of the Red Sea is just over 500 metres, and the maximum recorded depth is just under JOOO metres. The depth of the • sill is approximatel y 100 metres. (Pa.tzert, 1972) FHYSICGRAPHY The topography of the Red Sea is dominated by two principle features; • a broad, smooth continental shelf and a deep axial trough-which is itself split into an even deeper axial valley. There is also a large area c1' vip;orously growing-coral, which is best considered as an independent • feature. 'fhe coral reef zone of the Red Sea is defined by depths of less than fifty metres. Here, reefs of every kind are found: elevated shore • reefs, barrier reefs, fringin~ reefs, pinnacle reefs, and dead reefs. The southern half of the Red Sea has reefs extending far out on both sides, 1P-.1vinr.: only a narrow, but deep passage in the mid.dle open for navigation• • T'hr. ~ (•rth0rn half has fewer and thinner reefs, but there are thick reefs "(Uanlir~ thr. entra.nces to the Gulfs of Suez and Ac1aoa. DPcnrdlng abrtfenly from the coral reef zone to depths of around • 500 to ~00 metres, are the coastal shelves. These, like the coral reefs, are broad in the southern half and narrow in the north. Average shelf denths ~.re also much greater in the north • Th9 region from 606 metr es down is considered the axial trough. It rlJn~: t.lic entire len.c:;t~ of the sea. In fact, ci.P,e11 waters of more tha.n • 1000 metres extend right up to'the southern tip of the Sinai Peninsula. At about 23 ~ !! and continuin,cs south to 170 H, the axia.l trough is split into Rn even deener axial valley, which plunges at its deepest point to nearly 3000 metres. Bottom photographs of the axial valley taken by va.rlous oceanographic research vessels,indicate that it was formed hy rec~nt spreading of the sea floor. These photographs show fresh volc~nlc fnatures such as fissures, cr~cks, and recent lava flows. South of 174.) N, the axial trough and valley are indistinguishable, and south of 150 N to the southern boundary of the Red Sea, the axial trough disAppears, grading into the continental shelf. (Morcos, 1970) (A bathyf'.letric cha.rt of the Red Sea is shown below.) <;'>'6~<;> y...\<:' EGYPT '?_0<'-s~.., ANGLO· EGYPTIAN SUDAN CLIMATOLOGY With the exception of the northern part of the Red Sea which is dominated by persistent winds from the northwest, the rest of the Red Sen is ~utject to the influence of reBular and seasonably variable wlnds,(Morcos, 1970) driven mainly by the summer and winter monsoons over centrnl Asia. The summer monsoon causes wind3 primarily from the northwest, while the winter monsoon blows in the opposite direction, fro~ the southea.st. All year round, the winds over the Red Sea .are constrained to flow bnsically parallel to the sea axis due to the high mountains CJnrl "'Jhteaus on both sides of the se~. . Hear the coasts however, the winrls ~ltcrn~te between a ni8ht land br eeze and a daytime sea breeze, 12 • • • • • µ li j • 1i il' •I :.,I f' 'I • • • • • f3 • 339 auA to larf':e daily differences -i_n local heating. (Patzert, 1972) R.?Jnf.i.11 over the Red Sea and its coasts is slight. Rain that ec1es of phytoplankton ·recorded from the :Indian o. ar~ not found in the Ped Sea. Only 170 of 452 species of Indian Ocean dino~lagellates are represented in the Red Sea. However, again as with the zooplankton, there are a number of species considered as endemic to the • ned SP~. (Kimor, 1973) The rtecapod crustaceans are the best known inhabitants of .the deep sea re~lon of the Red Sea. Many species of this group from the Indian • Oce3n are missin~ in the Red Sea, evidently because they cannot tolerate the hi~h temperatures or were unable to overcome the high entrance sill. But the d~canoas which in the Indian Ocean are confined to the u pper shelf • • • descend in the Red Sea into the deeps, which conforms well with the temnerature gradient of this sea. Mollusks, mainly gastropods, comprise most of the rest of the deep sea animal groups. In the shallower regions of the coastal • waters, sponges, echinoder ms and ascidia.nSare found. The larger fauna of the Reel Sea include kingfish, groupers. stingrays, barracouda, and sharks , to name a few • • SCME ECCNOMIC ASPECTS Very li.ttle work has been done on the economic pote~tial of the Red Sea. Anart from t he conventional exploitation of fisheries , a couple of 'imaginary' nrojects h~ve been nroposed. The Woods Bole branch of the U.S. Geological Survey has estimated that the heavy metal deposits in the Red Sea offer an ore potential of about 130 million tons. This is a conservative estimate considering it is based only on the • Atlantis II Deep area and a thickness of only ten metre~ :'or the ore body. Seismic records indicate that the thickness of the beds could well be more than • 100 metres. Another possible project concerns the sill at t he Strait of Bab-el-Mandab. In arid zones, such as the Red Sea, where evaporation exceeds rainfall and run off • from rivers, the sea level is maintained by the i nflow being larger than the outflow. If the Strait connecting the Red Sea and Gulf of .Aden is damned, the sea level will continue to decrease until a sufficient head of water between the Red Sea • ~.nd Gulf of Aden is attained. The ocean water, a.dmi tted through a channel, and acting on turbines, would be able to generate immense quantities of hydroelectric power• • CCNCLUSI ON Honefully it is now clear that the Bering Sea and the Red Sea, two marginal seas, have very little in common. They differ in temperature,• salinity, nutrient input, fish cafch and productivity, to name but a few Darnmeters. Not all ma-r.ginal seas are ac differeEt as these two, but these • ma'f.':e -~ood examples to show how varied marginal seas can be. The main thing to remember when considering marginal sea ecosystems is that no two marginal seas are t he same, and that the marine ecosys~ms associated with • them are as varied and numerous as t he marginal seas t hemselves . REFERSNCES Dov Por, H'rancis, t978, Lessepian Migration,Sp:!."'lnger-Verlag Berlin • Heidelberg, New York. E~man, Sven , 1953, Zoogeoeraphy of the Sea, Sidgwick and Jackson Ltd., London, B]ngland . • 'C'a,irbridge, Rhodes, W., 1966, Encyclopedia of Oceanography, Reinhold nublishing Corporation, New York . Gross, M. Grant, t 977, Oceanogra:phy; A View of the Earth, Prentice • Hall Inc., Englewood Cliffs , New Jersey Gulland, J.A., 1971, Our Changing Fisheries , United States Printing Office, Washington, D.C. • Kimor, B.Plankton Relations in the Red Sea, Persian Gulf, and Arabian Sea (article from) The Biology Of The Indian Ocean, Edl ted by Bernt Zeitschel, 1973, Springer-Verlag Berlin Heildelberg • Marshall, N.B., Recent Biological Investigations in t he Red Sea, 1952, Endeavour Magazine 11: 137-142 Morcos, Selim A. Physical and Chemical Oceanography of the Red Sea, • Oceanography and Marine Biology Annual Review, _1970, 8, 73-202 p,q_rold Barnes, Ed., George Allen and Unwin Ltd., London Patzert, William C., 1972, Seasonal Variations in Structure and Circulation • in the Red Sea, (Dissertation) , Hawaii Institute o: Geophysics Pao, T.s.s., Zoogeography of the I ndian Ocean, 1979, Zoogeography and Diversity of Plankton, S. Vander Spoel, Ed., Halsted Press, New York. • • L____ • • Sears, Mary, 1961, Oceanography, Horn Schafter Co., Baltimore, Maryland Shapiro, Sidney, 1971, The Fish Resources of the Oceans, Fishing News, Ltd., West Byfleet, Surry, England ..; () Sperdrop, H.O., The Oceans, 1942, Prentice-Hall, New York Thurman, Harold V. Introductory Oceanography, 2nd Ed., 1978, Charles • E. Merrill Publishing, Co., Columbus, Ohio • 7,enkench, Lev Aleksandrovich, 1963, Biology of the Seas of the USSR, George Allen and Unwin Ltd., London, England. ~odd and Kelly, 1974, Oceanography of the Bering Sea, Vail-Ballou • Press Inc. , USA Outer Continental Shelf Environmental Assessment Program, 1979, Environmental Assessment of the Alaskan Continental Shelf, Science Applications Inc., Boulder, Colorado • • • • • • •