4. Homework-Answer this question and email it to   biovcc@Gmail.com

HW  4  1. What factors account for the vast majority of atolls in the Indian and Pacific oceans and that atolls are rare in the Atlantic ocean and b. Why are there no coral reefs off the Northeastern coast of Brazil even though it lies in the tropics?

2. Some of the organic material manufactured    in the estuarine communities is exported to other ecosystems.    What type of ecosystems receive this material? How is this material transported?


Coral Reefs

*Single coral reefs may cover over 100 sq km: massive structures that have been built almost entirely by marine plants and animals. The material of the reef is calcium carbonate: limestone derived from the surrounding waters by the reef organisms.


*The living reef forms the top layer of the reef adding new limestone to these massive structures at rates that can be measured annually at KG's for every square meter of the reefs surface.


*The corals are probably the most oblivious life forms on the reefs. All the different colors and shapes made up of thousands of individual polyps, each secreting its own small cup of coral limestone, which provide the building blocks for reef construction. But plants are also important in the development of this system as many secrete limestone!

*Coralline algae, in particular, form cementing crusts that act as 'mortar' for the coral 'blocks'.

*Coral reefs have existed in the earth's shallow seas for a long time, probably in excess of 450 million years;


The scleractinian corals that succeeded the rugose forms probably evolved in the warm waters of the Tethys Sea,

•It was eventually closed by the gradual northward migration of the southern continents, a process known as continental drift.

*The Australian continent was also on the move and slowly drifting northwards from the cold polar latitudes and into the warmer waters of the tropics and by chance ventured into this area rich in coral growth...its northeastern shores in particular were bathed in the ocean waters passing through the coral rich seas. (Great Barrier Reef)

*With the great environmental fluctuations in the earth's history, sea levels have oscillated from positions slightly higher than the present to at least 150m below the present level.

*Florida is the only state in the Continental US to have extensive shallow coral reef formations near its coasts. The reefs extend from near Stuart on the Atlantic east coast to the Dry Tortugas, west of Key West in the Gulf of Mexico. The best reef development occurs in the Florida Keys.

*These reefs may rival some of the Caribbean areas and number about 6000 between Key Biscayne and the Dry Tortugas

These reefs came into existence 5-7000 years ago when the Wisconsin Ice Age ended and the sea level rose. The growth is slow and estimates range from one to 16' every 1000 years.

*Live-bottom biotas

WORM REEFS Aggregations of the tropical reef worm (Phragmatopoma lapidosa ) construct low reefs of tubes consisting of sand grains cemented together by protein. The reefs expand as worm larva settle on existing tube masses.

•The reef growth is controlled by waves bringing planktonic food and sand to the worms. Found from Cape Canaveral to Key Biscayne and best developed off St. Lucie and Martin Counties...Bath Tub Reef.

*Oculina Banks

Coral banks that occur offshore from JAX to St Lucie inlet at depths of 50-100m are another of Florida’s little known reef types. The banks are constructed by the ivory tree coral (Oculina varicosa).


*Stony corals are the major reef architects. These small marine animals, called polyps, produce a hard skeleton made of calcium carbonate, which they extract from the seawater and combine with CO2 for limestone

*Some corals grow in colonies that continue to enlarge year after year, and some are solitary and live alone. Together they can form enormous colonies that are called coral reefs, coral islands and coral atolls. The largest, being the Great Barrier Reef, is 1,250 miles long.

*They can exhibit many shapes, sizes, and colors and reefs look like underwater gardens (although they usually lose their colors when removed from the water except red coral).


*And though reef corals are classified as animals, there is a complex of microscopic plants called zooxanthellae, which live within the animal tissues (symbiosis) and the animals benefit from the energy that the plants provide through photosynthesis.



•These dinoflagellates gain nutrients from the corals nitrogen and phosphorus wastes. They are also responsible for most of the colors of the reef.

•These specialized habitats provide shelter, food, and breeding sites for numerous plants and animals and form a breakwater for the adjacent coast, providing natural storm protection.

*They are also important to South East Florida's economy.


*Reef development occurs only in areas with specific environmental characteristics:


•            a solid structure for the base,


2.warm and predictable water temperatures and oceanic salinities, s

*3. clear, transparent waters low in phosphate and nitrogen nutrients,


4.and moderate wave action to disperse wastes and bring oxygen and plankton to the reef.


*Corals live in all oceans of the world from the Arctic and Antarctic to the tropics. The largest reefs occur in the warmer portions of the Pacific and Indian oceans however they are also found in the Caribbean and Gulf of Mexico and southern Florida.

*Numerous species occur in the different areas ranging from 40 or more in the West Indies to 200 or more on the Great Barrier Reef (because of their great skeletons, their fossils have yielded more than 6000 extinct species.)

*Corals can live in water below 68-70 degrees (reef min. temps) but don't form reefs, just like some corals which can live 19,000 feet below the surface, but reef-building corals are in water usually less than 300'.


*There are three types of reefs,

•            fringing, which follow the coastline and form along the coast,

2. barrier reefs, which lie parallel to the coast and separated by a narrow lagoon, and

3. atolls, which are associated with rims of extinct volcanoes which sunk back into the ocean leaving a circular rim of coral around a deep lagoon.

*Every year careless boaters run aground destroying coral colonies hundreds of years old. From the surface reefs have a unique golden brown color. If you see brown, you may be about to run aground. Anchors, hooks traps and touching all injure or damage or destroy corals by leaving it vulnerable to infection by microscopic organisms that can kill the animals.


*The Animal

The adult coral, stationary at this stage in life is called a polyp which can reproduce in two different ways. One is by means of eggs that, when fertilized by sperm, develop into tiny swimming larval organisms called planulae.

*They eventually settle down on the bottom of the ocean, on a rock etc. and develop into polyps. Each polyp builds a limestone skeleton attached to the surface on which the polyp has landed. After establishment, the upper part of the polyp becomes domed shaped, develops a body and a mouth with tentacles around the mouth used to draw in food from the surrounding waters.

*The tentacles are armed with specialized stinging cells called nematocysts that paralyze tiny prey. (mostly at night)

*Another process is by budding which offshoots called buds grow out from the body and remain attached sending out more buds.

*The coral reef has a very high order of internal organization, greater even than the tropical rain forests they are often compared to. Both receive high levels of solar radiation, the ultimate source of all ecosystem energy.

*2 CLASSES of reef corals exist, HYDROZOA AND ANTHOZOA. In the keys, Millepora (fire coral) is the only hydrozoan coral on shallow reefs. Stylaster and Distichophora are found in deep habitats.


The anthozoans include octocorals, zoanthids, stony corals, false corals, and anemones.

*FIRECORAL...MILLEPORINA The stinging/burning comes from nematocysts. 2 species of firecoral are found in Florida reef. The bladed is a keel shaped (M. complanata) restricted to shallow windward reef tops. Crenulated (M. alcicornis) is a branching species found in a much wider range of reef habitats.


*Fire corals are successful in colonizing living octocoral branches.


* Coral reefs can only grow up to about the level of a low spring tide, and reefs (as opposed to individual corals) will probably not develop in water more than 40m deep. Reefs are, therefore, strongly influenced by sea level. Over the time that most of the world's reefs have grown, there have been major sea level changes.

*There were two main reasons for sea level changes. One, the worlds ocean basins have changed in size and shape because of sea floor spreading and plate tectonics and the other is the ice ages.


In the last 8000 years, reefs have grown to what they are today. They have grown from the older reef platforms about 15-20m deep. The modern reefs are relatively thin and their shape reflects accurately the shape of the surface over which they are growing.

Coral Reefs

*To understand the growth of modern reefs, its best to begin at the surface, where five easily defined zones can be identified:

Coral Reefs

*1. the reef front,

2. the reef crest,

3. the coral flat,

4. the sand flat, and

5. the lagoon.




Coral Reefs

*The upper slope of the modern reef front extends from the mean low-water level of spring tides down to a depth of 10 to 20m. Fairly steep, sometimes vertical, sometimes terraced, and often serrated by coral covered spurs and channels, the area has a lot of coral cover.

Coral Reefs

* On some reefs, the front is protected by a line of patch reefs, many of which are joined to form an outer front.

Coral Reefs

*The exposed windward reef crest, or outer reef flat, lies above the mean low-water level of spring tides. It is composed of either a seaweed, stepped surface of encrusted coralline algae and devoid of corals, or a flat coralline-encrusted surface that may reach half a meter above the mean low-water level of spring tides, as on a ribbon reef.

Coral Reefs

*The upper surface of the reef crest is sometimes covered by a green turf of fleshy algae, which provide a home for countless small organisms, particularly foraminifera. These algae pavements can reach 200-300m wide and form in response to the high energy conditions typical of windward edges.

Coral Reefs

*These algal pavements are replaced by extensive coral development in lower energy or more leeward parts of the edge of the reef.

The coral flat or reef flat, occurs on the sheltered or lee side of the algal flat. It usually consists of an aligned coral zone where most corals are encrusted by coralline algae.



Coral Reefs

*These aligned corals occur in patches 1 to 2 m wide and 20m long formed by coral growing parallel to the direction of waves refracted across the top of the reef. The water movement is channeled across the grooves between the aligned assemblages of coral and in this way, coral growth on the reef top controls the backward flow of water across the reef.

Coral Reefs

*Nutrients and sediments are carried back through these channels to the sand flat and lagoon areas. This zone is usually separated from the lagoon by a sand flat, sometimes up to 500m wide. The sand flat is made up of broken skeletons of corals, coralline algae, and other reef organisms derived from the reef front and coral flat and transported toward the lagoon as sands and gravels

Coral Reefs

*Foraminifera from the algal turf of the reef crest also form part of this sediment.

Sand flats have been built by prevailing swell and waves that continually destroy the reef front and transport the broken products backwards.

Coral Reefs

*The surface of the sand flat, covered by one half to two meters of water, depending upon the tides, is often sparsely covered by small colonies of branching corals which can grow from fragments brought from the coral flat which grow when they come to rest.

Coral Reefs

*In this way, the coral flat extends backward across the sand flat, and the sand flat will migrate into the lagoon

The lagoon is best seen in platform reefs, where they reach 5-10m deep with the deepest part on the leeward side of the reef

Coral Reefs

*Lagoons are sometimes open with very few patch reefs rising from the floor or often very crowded with patch reefs making navigation of the lagoon difficult...

Coral Reefs

*They are made up of many species of branching and massive corals, the dead parts of which are encrusted by coralline algae. The lagoon floor consists of coral sand, which becomes finer away from the windward margin and patches of mud (very fine) sometimes occur in the quiet waters of the leeward margins.

Coral Reefs

*Because the lagoons are depositories for sediments and organic material created on the windward margin, they are slowly filling up.


Coral Reefs

*About 6000 yrs ago, sea level established and maintained a position close to what it is today.

Coral Reefs

*The composition of the reef also varies with the position of the reef on the continental shelf. The structure of the outer shelf-reefs generally reflects the influence of powerful waves, and here most of the reef consists of coral skeletons forming a porous, but relatively stable framework.

Coral Reefs

*Reefs in the middle and inner parts are dominated by accumulations of sand, and the coral framework forms a much smaller proportion of the reef, reflecting the calmer sea, or lower energy conditions compared with the outer reef.


Coral Reefs

*3 stages of reef development can be seen.

1. vertical growth to sea level...a reef growing slowly from a deep substrate may not yet have reached sea level or only recently have reached sea level and is characterized by vigorous growth of free-standing branching or massive corals upwards to sea level. Such a reef is termed juvenile.

Coral Reefs

*2.A reef growing from relatively shallow substrate, or one growing rapidly from a deeper substrate, will reach sea level quickly and will be subject to the influences of shallow water for a long time...many have been at sea level for 4 to 6000years. Swell, waves and currents help develop these and these reefs are called mature.

Coral Reefs

*3. Reefs growing from very shallow substrates, or small reefs that have grown rapidly from deeper substrates, may have been at sea level even longer than mature reefs and because a long time at the surface leads to destruction of the reef, lagoons will have been filled in and the typical zonation destroyed. Erosion is thought to exceed production, and such reefs are called senile.


Coral Reefs

*It’s believed that reefs progress through the growth stages from juvenile to mature to senile. Different reefs require different lengths of time to follow this progression, the time being dependant on depth and size of substrate, rates of growth, length of time at sea level, and intensity of the processes operating at sea level.

Coral Reefs

*As reef growth has seldom lasted for more than 5000-15000 years, some large lagoon reefs may not have sufficient time to progress through the complete cycle in one high-sea-level growth phase and could need more than one growth phase to reach a senile condition.


Coral Reefs

*Maintenance and Destruction

Reefs come in a vast array of shapes and sizes and many of these differences result from erosion while periodically exposed during low-sea-levels rather than from growth differences


Coral Reefs


A coral reef requires only the basic plant nutrients plus a copious supply of calcium for the construction of the calcium carbonate of the coral skeletons and other limestone forming materials of the reef. Carbon dioxide and calcium are abundant in sea water.

Coral Reefs

*N, P and some trace elements may only be present in limited quantities in the clear oceanic waters and the reef must recycle these materials to maintain its intense biological activity.



Coral Reefs

*All plant and animal matter grown must be totally consumed or fully degraded within the reef community to prevent the loss of any nutrients. Extensive mats of blue-green algae on the reef may provide the reef with N by converting the N in the atmosphere to the soluble inorganic N nutrients.


Coral Reefs

*There are very small but important losses and gains from any reef system and that is the exchange of larval forms with other reefs. This ensures inbreeding and that any species depleted by disease or other stress will be replaced by larval input from another reef or reefs.

Coral Reefs

*About 3/4 of the CO2 that is removed from sea water by a coral reef in each 24hr period is used directly in photosynthesis within the reef algae. This creates about 20g of new organic matter for every square meter of shallow, reef-flat environment per day and can be up to 50g a day in areas of intense biological activity. This is the reefs food supply.

Coral Reefs

*Most of the limestone making up the solid underlying mass of the coral reef consists of skeletons of once living corals.

Coral Reefs

*They provide the aggregate of the reef concrete. At least some of the corals in this rich surface growth are likely top add to the structural framework of their own reef when they die.

The encrusting coralline algae hold together the sand and framework materials of the reef to create a solid surface.

Coral Reefs

*They have a role in building a real reef rather than a pile of uncemented coral debris and sand. Once the reef has been totally consolidated by these algae, chemical precipitation of more carbonates in the reef structure provides additional cementing of the remaining loose calcium carbonate materials.

Coral Reefs

*It’s a slow process but it makes the entire structure more rigid. The final reef material is a porous but strong limestone, though it frequently contains uncemented regions.



Coral Reefs


Direct feeding by the polyps usually only supplies only 10 per cent of the corals energy needs. In such cases, most energy comes from photosynthesis by zooxanthellae, which obtain nutrients from metabolic waste products of the coral host as well as from the seawater or detritus.

Coral Reefs

*Coral reef primary productivity is usually very much higher than areas where these nutrients are more abundant but recycling rates of the corals and zooxanthellae are high but the harvestable primary productivity is low because most of the organic matter produced is metabolized and nutrients are freed to be reused in photosynthesis.


Coral Reefs

*Almost every gram of organic matter created by a coral reef is consumed and eventually finds its way back to the seawater as carbon dioxide. Before most of the organic matter is finally degraded back to CO2, it may move through all or part of the complex and finely balanced coral reef food web.

Coral Reefs

*Reefs may be thought of as assemblages of beautiful animals but in fact they are dominated by the activities of plants. The whole system is driven by the photosynthetic activities of plants, just like most ecosystems existing in light.

Coral Reefs

*Even the corals function principally as plants, deriving as much as 90% of their total and energy requirements from the tiny algae, known as ZOOXANTHELLAE, contained within their coral tissues. The remaining requirements are met through feeding on reef plankton.


Coral Reefs

*Apart from the corals, the major plants providing the food supply of the reef are fine filamentous algae that form a rapid growing fuzz or turf over almost all available surfaces within the reef. This turf is grazed by animals, which in turn are preyed on by larger animals and so the food web expands.

Coral Reefs

*Also, all living materials die and undergo microbial decay, forming the basis of yet another component of the complex food web.

•.The reef also creates and consumes its own plankton. Each animal and plant serves a vital role in the reef's finely tuned balance.


Coral Reefs

*. The Factory

The 10 to 30 grams of calcium carbonate or limestone created everyday for each square meter of the active parts of the reef are retained somewhere within the general reef environment. The reef thus exhibits real, measurable growth over hundreds of years.

Coral Reefs

*. The energy to enable the creation of all this limestone comes into the system through algal photosynthesis. Much of the limestone originates as growing coral but other organisms, such as many algae, tiny single celled forams, and shells make major contributions.


Coral Reefs

*. Photosynthesis by zooxanthellae also promotes production of skeletal limestones that make up the reef framework. Zooxanthellae provide coral with the energy needed to calcify.



Coral Reefs

*. Photosynthesis uses CO2 and water from respiration raising the pH of the system end enhancing aragonite precipitation.

During calcification, calcium ions, which are abundant in seawater, combine with bicarbonate ions, also found in the environment and the following reaction occurs...


Coral Reefs

*1 -Ca2 + 2HCO3 -----> Ca(HCO3)2 and then calcium carbonate and carbonic acid are produced...

2- Ca(HCO3)2----->CaCO3 + H2CO3

but carbonic acid can't exist so carbonic acid must be ionized

3- H2CO3---> H+ + HCO3- or converted to water and CO2

4- H2CO3----> H2) + CO2

Coral Reefs

*. Destruction

One of the obvious of all reef destroying processes are storms. But not all reef destruction is caused by physical forces. Many animals and even some algae live out their lives inside the reef structure and even in the skeletons of still-living corals and other organisms with hard skeletons.


Coral Reefs

*. Some of these graze off of the reef surfaces and remove considerable amounts of the limestone at the same time. These boring and grazing organisms weaken the structure of their host or the reef itself by physically disrupting the limestone materials.


Coral Reefs

*. This in turn, forms more fine sand and calcium carbonate detritus in the reef system. But the boring organisms also dissolve, using acid secretions, much of the calcium carbonate they remove (about 5-25% of total CaCO3 deposited by the reef)..



Coral Reefs


 Of course, grazing and predation can be readily observed but on coral reefs, disease, competition, chemical warfare, bioerosion and symbioses are also common.

Pathogens may injure and kill corals, and black band, one such pathogen usually attaches to a coral following tissue damage.

Coral Reefs

*.Competition include overgrowth denying light and water movement.

Allelopathy (chemical defense and offense) is also used to prevent overgrowth and gain living space.

Damselfish destroy coral tissue and farm/defend algae on the dead coral.

The black sea urchin crops algae from the reef and this provides settlement habitat for coral larvae.

Coral Reefs

*. Sponges bore into coral skeletons, weakening them, some bind to them and some protect the undersurface from attacks by boring organisms.




The hobbyist idea of "soft corals" is quite different than the actual definition. True soft corals, according to the definition, all belong to the subclass Octocorallia. The name "Octocorallia" refers to the fact that each polyp has eight tentacles.


Colt Coral
Genus: Alcyonium


This can be confusing since many 'soft corals' are not actually soft. This definition includes such corals as the "Blue Coral", Heliopora coerulea, the Pipe Organ coral Tubipora musica, and the Gorgonians, all of which produce hard shells or skeletons.


Another characteristic of true soft corals are the side branches of the polyp tentacle, called 'pinnules

', which give the polyps a feathery look. Although pinnules are a sure sign of a soft coral, not all soft corals have them.

The gorgonians are soft coral colonies that are tree like. They attach themselves to rocks at the base and have a skeleton that is similar to animal horns. \\ Estuaries


•Questions to ponder…

·   An area where conditions prevent the growth of salt marsh plants in the intertidal zone is the………..

·       When fresh water pushes into an estuary overriding the denser salt water, the saltwater enters the estuary along the bottom and forms a ……….

·       The result of water movement through the estuary is cleansing and known as…….

·    Which is an example of a stenohaline organism? 

·    An organism that can tolerate wide ranges of salinity are known as…

·    How can  estuaries form?

·   The estuarine environment is characterized as a ___________ zone

•Tides in estuaries do what?

•An estuary is a semi-enclosed coastal body of water which has free connection with the sea, thus is strongly affected by the tidal action.

•Estuaries are of immense importance and are frequently areas of high fertility and large phytoplankton and zooplankton populations.

•Its been estimated that 60 to 80 % of the commercial marine fisheries resources depend on estuaries for part of or all of their life cycle.  

•. Sea water is mixed with freshwater from land drainage.

•The estuary is not part of the coast but is a coastal feature with a continuous exchange of water between it and the sea.

It typically contains marine plants and animals having anatomical, physiological, or behavioral adaptations to the changing conditions found in estuaries.

They produce numerous kinds and vast amounts of sport and commercial fishes and provide numerous other ecological services of direct and indirect value to humans.

•Positive estuaries...the precipitation and runoff exceed evaporation and sea water is diluted.

•Neutral estuary...runoff+prec. =evaporation

•Negative or inverse estuaries...almost no freshwater runoff.

Currents in the estuaries come from tides, river runoff, transport by wind generated surface waves, direct stress by wind on water surface , variations in density distributions, and internal waves.

Plants and animals possess different tolerances for such physical parameters as salinity, consequently an estuary may be divided on the bases of salinity, each part corresponding to certain biotic classifications.

•Several terms are used interchangeable with estuary: wetlands, lagoon, slough, salt marsh, marsh, swamp.

•The term wetlands refers to land on which water dominates the soil development and thus the types of plants and animals that will live there.

The term lagoon is the region between a barrier island or spit and the mainland, a slough is a shallow estuary with large areas of the bottom exposed during low tides, a salt marsh is a shallow tidal estuary protected from ocean waves and inhabited by plants and can withstand submergence.

•The term marsh (used interchangeable with salt marsh) but in precise sense refers to a region with zero salinity upstream from a salt marsh.

•A swamp is a lowland area saturated with water often quite large and farther inland.

•It is common for coastal nekton to use estuaries as nursery grounds where young growth stages can take advantage of the protection and abundance of food .

•Since man often harvests such species offshore, the vital life history and energetic connections with the nearby estuary have not always been appreciated……..

•..and the dependency of so many important commercial and sport fisheries on estuaries is one of the major economic reasons for preservation of these habitats.

•Its estimated that 60-80% of the commercial marine fisheries resources depend on estuaries for part or all of their life cycle.

•The intertidal and adjacent shallow water zones are the most productive and most important and also the 1st to suffer the ill planned encroachment of man.

•Estuaries tend to be more productive than either the sea on one side or the freshwater drainage on the other.

•Formation of Estuaries

•Estuaries can form in many ways. 

•4 methods are:

•Bar Built



•Drowned River Valleys

Bar Built


San Francisco Bay


Drowned River Valleys

• The estuary is a nutrient trap, partly physical and partly biological.

•Retention and rapid recycling of nutrients by benthos, formation of organic aggregates and detritus, and the recovery of nutrients from deep sediments by microbial activity, and deep plant roots create a self-enriching system.

Pollution can also get trapped.

•There are three types of producers in the estuaries..

•  macrophytes,

•benthic microphytes,



•Detritus...involves accumulation and decomposition of dead materials.


Spartina sp. is the major producer and the microbial enriched grass detritus feeds consumers in creeks and sounds. The role taken by eel grass Zostera or seaweeds in colder water, Turtle grass (Thalassia) in warm waters...make contributions to productivity of sub-tropical and tropical lagoons.

•These sea grasses often support a large population of epiphytic algae and small fauna.

•Terrestrial and freshwater vegetation that lived in the low lying coastal regions during the ice age were killed as the advancing seawater moved inland.

•Grasses that could thrive in brackish estuarine environments colonized the salty mud and as the the roots of the plants grew down, trapping more particles, the estuary grew.

With each tide, planktonic larva of clams, mussels, crabs and worms settled among the plants and fish, birds insects and animals migrated to the young estuaries for food and living space.

•The salt marsh community is a relatively flat grass covered coastal area occurring within the estuarian ecosystems in temperate climates.

•Its partially flooded by tides (tidal march or wet land).

•The marsh can be thin or very wide and is one of most productive habitats in the marine environment.

•The four regions of the marsh are..

•Low marsh

•High marsh

•Salt barren region

•Transition zone


•Vast quantities of food are produced by marsh grass (Spartina) and algae that live on the surface of the mud.

•Photosynthesis is fastest at low tide and an ample supply of nutrients (nitrates, phosphates and sulfates) in the estuary make a high rate of food production possible.


•(nutrient rich water bought in each high tide).

•Blue-green algae convert atmospheric Nitrogen into nitrates .

•Salt marsh producers grow rapidly and absorb minerals at a fast rate.

•Spartina grass and other marsh producers have a short life.


•Floating seaweed and debris are dumped onto the marsh at high tide and as this and the marsh grass dies, teeming masses of bacteria break down the complex plant material into detritus.

•Isopods, insects, fiddler crabs, marsh snails eat the decaying plant tissue, digest it, and excrete wastes that include nitrate, phosphate and sulfate.


•By quickly converting the decaying material into inorganic material, these detritus feeders speed the growth of living marsh plants..

•Each tide carries much of the detritus and minerals into the offshore water with phytoplankton using the minerals, clams, mussels, worms, and sponges eat pieces of detritus.


•These excrete minerals when they break down the detritus adding more..and this rapid cycling of minerals is a unique feature of the tidal salt marsh, making the high rate of primary productivity possible.


Wetlands near cities also have an additional source of minerals for producers with the billions of gallons of sewage/treated and untreated, discharged into coastal waters (as well as PCBs bacteria, viruses heavy metals, which can be ingested by marine organisms and be passed on to humans).


•Food web

•Communities within estuaries are linked by overlapping food chains as energy flows from primary producers to consumers. (food wed).


Many primary producers are first converted by bacterial decomposition into organic detritus which serves as a major food source for the majority of consumers living in the estuarine community.


An important group of primary consumers living in estuaries are animals that feed on plankton and these are the most abundant species of vertebrates in estuaries because of the large supply of food available to them.


•The carnivores (predators) occupy the highest level obtaining energy by eating animals that feed on plankton and detritus.

•Predators are important to the estuary because of their end position in most consumer food chains.

•Part-time and full time residents feed there.


•Many migrating animals stop over for refuge and food in the estuary thus exporting the energy to other environments.

•One aspect of the estuary food web is that there are more different species of consumers than species of primary producers.

•A few provide nutritional needs to many.


Thus the usual trophic pyramid is inverted because most carnivorous species are at the top of the food web!




1.  How many miles of shoreline are found in the USA?

2.  Why are commercial fisheries dependant on estuaries?

3.  Define estuary.

4.  Name 4 ways estuaries are formed?

5.  What is a salt wedge?

6. What are some interchangeable terms with "estuary"?

7.  Why do coastal nekton take advantage of estuaries?

8.  What are the three types of producers in estuaries?

9.  Why is the high rate of food production possible in estuaries?

10.  What are the 4 areas of a salt marsh?

11.  What are some of the adaptations the cord grass has made to adapt to its environment?

12.  Why is the statement "the mud flat is a barren area because there is no visible plants on it" incorrect?

•               Why is the trophic pyramid inverted in estuaries?

•               14.  How is the role of bacteria and other saprophytes in estuaries necessary for the productivity of the estuary to be high?







Review answers Estuaries and Corals Review Answers

1. the sea invaded lowlands and river mouths as a result of rising sea level

2.          Norway

3.          decreases

4 up the estuary

5.          soft mud

6          can cope within a wide range of salinities

7.          take on water through osmosis

8.          height of the tide

9 tropical and subtropical

10  detritus

11 plants and seaweeds diatoms phytoplankton

12         dead organic matter

13 mangrove forests saltwater and freshwater marshes saltwater marshes tidal marshes

14         calcium carbonate

15         a planula

16. perform photosynthesis, and thus provide nourishment     help the corals produce their skeletons

17         capture of zooplankton with tentacles or mucus nets zooxanthellaeabsorption of DOM (dissolved organic material) from wateruse of mesenterial filaments

18 coralline algae

19         it forms calcium carbonate sediment

20         the zooxanthellae need light to photosynthesize

21         fringing reef

22         reef crest

23         along the coasts

24         spur and groove formations

25         the Indo-west Pacific region

26 turf algae

27         light

28         corals

29 grazers