Especially important is the author's recommendation that a study of 

 the detritus contributed by eel grass is needed, as to amount, type, 

 chemical content, caloric value, and the effect on the physical 

 structure of the habitat. (B.W.) 



Keywords: eelgrass, food chains, detritus, nutrient cycles, energy flow, 

 U.S. coastal regions 



I-A-8 



Gray, I.E. 1974. Worm and clam flats. Pages 204-243 iji H.T. Odum, B.J. 

 Copeland, and E.A. McMahan, eds.. Coastal ecological systems of the 

 United States, Vol. 2, The Conservation Foundation, Washington, D.C. 



The bottom surfaces of estuaries develop communities of invertebrate 

 animals (annelid worms, clams, and many other organisms) that obtain 

 foods derived from the waters above. The flat expanses of mud and 

 sand in the inter-tidal zone and deeper in the sub-tidal bottoms, with 

 their associated biota, are important subdivisions of the estuary. 

 Examples of worm and clam flats and the species associated with each 

 type are described. 



Five categories of benthic feeding types are discussed: (1) deposit 

 feeders, (2) suspension feeders, (3) scavengers, (4) carnivores, and 

 (5) omnivores. The largest and most characteristic is the basic 

 deposit feeding group. Deposit feeders consume not only detritus but 

 also living diatoms and dinoflagellates. The immediate sources of 

 organic detritus in the substrate range from dying and decaying 

 plants and animals and solid excreta from animals inhabiting the 

 waters, to organic debris from nearby terrestrial areas. Except 

 in estuaries well supplied with benthic vegetation, the organic 

 detritus is largely supplied from phytoplankton. 



The author presents a picture of the normal community relations, 

 including the relative abundance of organisms and their positions in 

 the food web, of a typical undisturbed intertidal flat. Sources of 

 stress which can make sudden and drastic changes in a estuary are 

 discussed: natural phenomena, silting, heated effluents, and sewage 

 pollution. (B.W.) 



Keywords: invertebrates, estuarine organisms, detritus, community 

 structure, U.S. coastal regions 



