It is noted that consumer nutrition is only one aspect of the organic 

 detritus problem. Many organic compounds released into the aquatic 

 environment have been shown to exert specific influences upon various 

 species. Such influences include growth stimulation or inhibition, 

 attraction or repulsion, and so on. Through its contributions to 

 turbidity, sedimentation, and chemical alteration of the environment, 

 organic detritus influences every major process active in aquatic 

 communities. (H.D.) 



Keywords: productivity, detritus, estuaries, food chain 



III-A-7 



Russell -Hunter, W.D. 1970. Aquatic productivity: an introduction to 



some basic aspects of biological oceanography and limnology. Collier- 



Macmillan, London. 306 pp. 



This book presents basic aspects of faunal productivity in aquatic 

 environments. Applied and theoretical considerations are discussed. 

 Basic biogeochemistry of organic cycles and biomass transfer between 

 different trophic levels is illustrated using marine and fresh water 

 examples. Factors controlling primary productivity and food chains in 

 various ecosystems are discussed. 



The author indicates that shallow coastal waters and semienclosed 

 areas of the sea can be characterized as sometimes more productive, 

 and always more variable in productivity, than waters of the open 

 ocean at the same latitude. In shallow coastal waters, the bottom 

 frequently supports a rich fauna, the benthic animals alone often 

 amounting to a standing-crop biomass in excess of 100 grams of living 

 tissue in each square meter of mud. In these circumstances, there 

 are fast local cycles of nutrient salts and rapid turnover of detritus. 



Waterborne detritus and the local crops of attached diatoms and 

 microscopic algae are important contributors to productivity in 

 estuaries and other brackish-water habitats. The length of time spent 

 in recirculation within the estuary may be of great importance in 

 allowing time for bacterial decomposition and proportionate change. 

 This can involve not only complete decomposition, which provides 

 increased nutrient salts for green plants, but also partial decompo- 

 sition, which renders detritus from marsh plants more suitable for 

 animal nutrition. (H.D.) 



Keywords: productivity, marine organisms, freshwater organisms, food 

 chain, seagrasses, algae 



93 



