At present, two major divisions, physiological and behavioral, exist within aquatic toxicology. With admitted bias, it appears to us that, in general, physiological toxicologists have presented a wealth of data on the effects of toxicants on a vast number of physiological variables. With the exception of morbidity, however, seldom do these data give insight into organismal effects (i.e., what do these physiological changes mean for the animal in terms of social interaction or behavioral performance?). In contrast, today's ethologists are primarily concerned with evolutionary adaptations and processes. This approach is not as useful in polluted waters, due to the frequent inability oforganisms to adapt to suchmassive disturbance of their habitat. With this in mind, behavioral toxicologists have presented data on the effects of some toxicants on specific behaviors. A cursory review of the literature would suggest that investigators seldom address the physiological mechanisms that explain how that particular behavioral effect was produced. Yet, it is clear to us that these two approaches, physiological and behavioral, are not and should not be mutually exclusive; they clarify and reinforce one another. 1 In this chapter, we seek to synthesize these two fields by

examining the full toxicant-physiological-behavioral axis and, in so doing, evaluate the effects of environmental contamination on the physiological mechanisms of behavior. Clearly, this is a nontraditional ethological approach.