In Figures 2 and 3, the chemical and physical characterization of the 

 chemical or effluent (Box 1) includes information on: rate of degradation, 

 absorption to colloidal materials, and combination (e.g., chlorine with 

 amines to produce chloramines) . The chemical and physical characterization 

 of the receiving system (Box 2) includes: likelihood that the system will be 

 displaced; and probability of recovery once the system is displaced (inertia 

 and elasticity). Some ecosystems, of course, are perturbation-dependent, for 

 example, the fire-dependent ecosystem in California. 



The third element of the evaluation protocol (Box 3), the determination 

 of testing priority, involved identifying the chemicals or other stressors 

 that deserve the most attention and the most detailed and sophisticated in- 

 formation base. During the laboratory screening tests in (Box 4), it is first 

 determined which of the trophic levels are most sensitive, and the effects of 

 environmental parameters on the response to a toxic compound. 



In the definitive laboratory tests (Box 6), one determines which is the 

 most sensitive life-history stage, because most commonly only one life-history 

 stage is used for the various organisms tested in Box 4. Then, the extent 

 that environmental parameters affect toxicity is determined. Third, how 

 stable is the material in terms of its toxicological characteristics? Does it 

 degrade rapidly or is it highly persistent? Four, does the substance produce 

 flavor impairment, making it toxicologically safe but esthetically objection- 

 able? Finally (Box 8), the potential for bioconcentration must be defined. 



CONCLUSION 



The questions that society might reasonably ask of biologists dealing 

 with the problem of hazard evaluation follow: 



1. What changes signal ecological degradation or harm to a species? 



2. What is the best established and most widely accepted method for 

 measuring each of these? 



3. Who is professionally qualified to make these measurements? 



Some progress is being made but it is far short of the need. It is worth 

 noting that the American Fisheries Society's certification program was an 

 enlightened step toward meeting the third of these needs. 



As a profession, biologists have been asking society to stop polluting 

 water ecosystems. We have emphasized the magnitude and importance of the 

 problem. Now society has indicated that it cares and wants to know how to re- 

 solve the problem. The professions that called attention to pollution are 

 now being asked to provide the methods and protocols for ecosystem quality 

 control and hazard evaluation. More research is almost always useful, but 



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