Effects of endosulfan on brain acetylcholinesterase activity in juvenile bluegill sunfish.

The effects of endosulfan upon brain acetylcholinesterase (AChE) activity were measured in juvenile bluegill sunfish (Lepomis macrochirus). Based on exposure durations of 0, 24, 48, 72, and 96h and 1 week at 1.0 microg/L (just below the LC50 of 1.2 microg/L for this species), step-wise decreases in AChE activity were noted, corresponding to 0%, 3.57%, 12.65%, 14.23%, 16.31%, and 23.11% inhibition, respectively. Total brain protein concentrations were measured to test the accuracy of the AChE data with no significant anomalies. The duration of exposure was related to the reduction in the AChE activities which reflected the biotoxicity of endosulfan. The changes in the AChE activities will certainly affect the normal behavior of the juvenile bluegill which is detrimental to their very existence in the natural habitat.