580 



istics should be determined, sine© combined effects are often worse than 

 the sum of individual effects. 



The need for hioassay procedures and -field testing 



The ultimate goal should be the development of rapid, practical, and 

 definitive bioassay procedures. These procedures should be designed 

 for multiparameter analysis in order to correlate the response to a va- 

 riety of icommon pollutants and environmental variations. In this way, 

 effective water quality criteria can be developed coupled with a capa- 

 bility for predicting biological effects. A major problem in the develop- 

 ment of these practical bioassay procedures to determine the water 

 quality requirements of estuarine and marine organisms is the lack of 

 suitable testing niethods. There is always the question about the realism 

 of work done in a laiboratory ; that is to say, how truly results so de- 

 rived reflect What takes place in nature. Test organisms in the labora- 

 tory are certainly not confronted with the complex interacting factors 

 which occur in the natural environment. Under natural conditions, 

 there may be a rapid reduction in the concentration of a toxicant by 

 precipitation, absorption on soils and bottom materials, chemical de- 

 composition, reactions with other su'bstances in the water, absorption 

 by microscopic organisms, removal by organisms, or biochemical degra- 

 dation. Accumulation of toxicants in the food chain and ingestion of 

 food organisms bearing relatively high concentration of these mate- 

 rials may increase the exposure to higher animals. 



Laboratory findings on the safe levels of potential toxicants must be 

 field tested under conditions wherein the organisms in question are 

 exposed to all stresses occurring in the natural environment. When 

 developed, tested, and evaluated, field studies can be used for simul- 

 taneously testing the entire community under natural conditions. Such 

 situdies integrate the effects of biological magnification; storage, pas- 

 sage through the food chain, accimiulation in bottom materials, com- 

 petition for food, cover, and living space ; disease, parasites, and preda- 

 tors ; synergism, antagonism, and the interaction of materials ; and all 

 other complicating factors present in the natural environment. 



To be a truly useful management tool, a catalog should be develojDed 

 indicating the tolerance levels of plant, animal, and bacterial estuarine 

 species for the pollutants so commonly found in the estuaries: sew- 

 age, heavy metals, industrial wastes, runoff from urban and agricul- 

 tural areas, oils, and a host of other materials foreign to the estuarine 

 environment. 



SUMMARY 



Wise management decisions require knowledge of the effects of po- 

 tentially toxic su'bstances as determined by long-range bioassay pro- 

 cedures extrapolated to natural conditions. Environmental levels of 

 toxicants which do not inhibit any portion of the life cycle, food chain, 

 behavior, or exert any detrimental sublethal effects must be determined. 



Section 6. Microbiology 



Microbiological aspects must be considered in a special category be- 

 cause of their widespread and diversified influence. Bacteria serve to 

 break down dead organic material and wastes into inorganic nutrients 



