Behavioral dysfunctions correlate to altered physiology in rainbow trout (Oncorynchus mykiss) exposed to cholinesterase-inhibiting chemicals

We selected four metrics of swimming behavior (distance swam, speed, rate o f turning, and tortuosity of path) and the commonly used biochemical marker , brain cholinesterase (ChE) activity, to assess (1) the sensitivity and re liability of behavior as a potential biomarker in monitoring work, (2) the potential for these endpoints to be used in automated monitoring, and (3) t he linkage between behavior and its underlying biochemistry. Malathion-expo sed fish exhibited large decreases in distance and speed and swam in a more linear path than control fish after 24 h exposure. By 96 h exposure, fish still swam slower and traveled less distance; fish fully recovered after 48 h in clean water. Diazinon-exposed fish exhibited decreases in distance, s peed, and turning rate compared to controls. After 48 h recovery in clean w ater, fish exposed to diazinon had not recovered to control levels. The beh avioral responses provided measures of neurotoxicity that were easily quant ifiable by automated means, implying that the inclusion of behavior in moni toring programs can be successful. Furthermore, correlations between behavi or and biochemical endpoints, such as ChE inhibition, suggest that this app roach can provide a meaningful link between biochemistry and behavior and c an provide useful information on toxicant impacts.