HUMIC MATERIAL CHANGES EFFECTS OF TERBUTYLAZINE ON BEHAVIOR OF ZEBRAFISH (BRACHYDANIO-RERIO)

The long-term sublethal toxicity of the triazine herbicide terbutylazi ne (TEA; 1, 5, 50, 200 mu g/l) alone and in presence of dissolved humi c material (DHM; 2 mg TOC/l) on zebrafish (Brachydanio rerio) has been studied. The effect of the tested substances on behavior were investi gated by recording and quantifying their spontaneous locomotor activit y using the BehavioQuant(R) system. Data were analysed by the Hasse di agram technique. For the parameter light-dark-preference, but not for the parameter inconstancy of motility, a clear concentration-effect-re lationship for the groups under TBA as well as for the groups under TE A + DHM exposure could be found. Comparing TEA and TEA + DHM treated g roups for both test parameters the presence of DHM increased the toxic effect of TEA on zebrafish for the preference and decreased for the m otility. The main result is that the preference follows an additive pr inciple, but not the motiliy. Hints for the influence of at least two different mechanisms controlling these behavioral parameters are discu ssed. Copyright (C) 1996 Elsevier Science Ltd