APPLICATION OF MULTIPLE BIOINDICATORS TO DIFFERENTIATE SPATIAL AND TEMPORAL VARIABILITY FROM THE EFFECTS OF CONTAMINANT EXPOSURE ON FISH

Bioindicators of fish health were measured from 1989 through 1994 in p opulations of redbreast sunfish (Lepomis auritus) at three sites withi n a stream receiving inputs of mixed contaminants from an industrial f acility, and at two reference sites, Bioindicator responses differed f or fish from contaminated and reference sites throughout the study per iod, but temporal trends at contaminated sites reflected improved wate r quality associated with pollution-control efforts, Temporal variabil ity unrelated to contaminant exposure strongly influenced the response of bioindicators at both reference and contaminated sites, but spatia l variability rarely influenced these responses, Temporal variability was less influential on slower responding indicators at higher levels of biological organization. The diverse response characteristics of in dicators increased the ability to differentiate natural from anthropog enic sources of variability, Integrated bioindicator responses were co mpared among site-year groups by multivariate canonical analysis, The primary canonical variable, associated with differences in growth, exh ibited trends consistent with the timing of pollution-control efforts, Two indicators of contaminant exposure (7-ethoxyresorufin O-deethylas e activity and polychlorinated biphenyls in fish muscle) also exhibite d trends consistent with the timing of pollution-control efforts, but the likelihood of possible mechanistic linkages cannot be assessed wit h available data.