DISRUPTION OF PRECOPULA IN GAMMARUS-PULEX AS A RESULT OF BRIEF EXPOSURE TO GAMMA-HEXACHLOROCYCLOHEXANE (LINDANE)

Precopulatory pairs of Gammarus pulex were exposed to each of 3 concen trations (0.5; 1.0; 2.0 mg l-1) of Gamma-hexachlorocyclohexane (Lindan e) for each of 3 exposure periods (2; 10; 20 min). A total of 14 treat ments (including 5 controls) was tested each of them involving 24 indi vidual pairs. Premature disruption of precopula as a direct result of exposure occurred in the exposure treatments 0.5; 1.0; 2.0 mg l-1 (20 min), 1.0 and 2.0 mg l-1 (10 min), and 2.0 mg l-1 (2 min). The disrupt ive effect was more apparent during the first hours of post-exposure, and at 2 h, disruption of precopula ranged from 60.0 - 95.8%. Recovery of precopula occurred to different extents in all affected treatments from 4 to 72 h after exposure. The median precopula duration, LP50 (h ) was estimated for 11 of 14 treatments, and also of recently formed p airs in contaminant-free artificial pond water at 15-degrees-C.