To adequately assess the influence of contaminants on the aquatic envi- 

 ronment and to overcome the avoidance of biochemical and physiological test- 

 ing, investigators should develop techniques that can serve as biological 

 indicators in the field as well as predictors in the laboratory to estimate 

 the "health" of a particular aquatic resource. However, biochemical and 

 physiological changes must be viewed in light of the degree and duration of 

 change to determine whether the organism can adapt or whether the changes 

 lead to irreversible homeostatic disturbances and finally to the death or 

 debilitation of the organism. 



BEHAVIOR 



Any alteration in the ability of an organism to perceive and respond to 

 its environment will affect its survival and may increase ecological morta- 

 lity. Reports on behavioral changes induced by toxicosis cover an array of 

 behaviors, and diverse techniques have been used to study these. The extent 

 to which these methods can be applied in toxicological investigations de- 

 pends on the economy of the procedure as well as on the accuracy with which 

 behavioral changes can be quantified. Two contaminants, or even two concen- 

 trations of the same contaminant may affect different behavioral responses, 

 and behavioral alterations caused by a substance may vary among species. 

 Thus, toxicological studies should rely on multiple behavioral responses. 

 The following behavioral responses are being evaluated as routine screening 

 tests for the effects of various contaminants. 



1. Avoidance - Aquatic organisms avoid certain comtaminants and 

 are attracted by others. When a contaminant is introduced 

 through either arm of a Y-maze, avoidance reactions have been 

 shown to occur in mosquitofish ( Gambusia affinis ) to insecti- 

 cides (Kynard 1974), in rainbow trout ( Salmo gairdneria ) to 

 herbicides (Folmar 1976), in shrimp and mosquitofish to PCB's 

 (Hansen et al_. 1974) and in Atlantic salmon ( Salmo parr ) to 

 heavy metals (Sprague 1964). 



2. Predator-prey relationships - Various contaminants also dis- 

 rupt predator-prey relationships by changing locomoter res- 

 ponses such as swimming or activity levels, or by disorienting 

 the organism or by impairing its ability to perceive a preda- 

 tor or prey. Several studies have shown that the certain con- 

 taminants may increase the prey organism's vulnerability to 

 predation (Goodyear 1972; Kania and O'Hara 1974; Tagatz 1976; 

 Farr 1977; and Sullivan et al. 1978). 



3. Feeding and swimming activities - The survival of recently 

 hatched fry or invertebrate larvae depends in part on the time 

 at which specific behavioral patterns develop. Delayed or in- 

 hibited behaviors such as feeding or swimming have been shown 

 to occur as a result of contamination (Dill 1974). 



Specific behavioral effects caused by contaminants are being correlated 

 with other biological characteristics such as pathology, biochemical aber- 



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