Experimental And Field Studies On The Toxicological Effects Of Microcystins On Phytoplanktivorous Fishes

Little is known on the toxic effects of MC on the phytoplanktivorous fish that are frequently exposed to cyanobacterial toxins because of their habitat and feeding mode. The mechanisms implicated in the high resistance of such fishes to MC have not been elucidated yet. The purposes of this study were to examine, through both acute toxic experiment under laboratory conditions and field investigation in fish pen, the changes of MC concentration, histo- and ultrastructure of liver and kidney and serum biochemical parameters as well as biochemical responses of antioxidant and detoxification systems in the phytoplantivorous silver and bighead carps and to discuss the toxic effects of MC on these fish with comments on the possible mechanisms of high resistance and detoxification capacities in phytoplantivorous fish. The results were summarized as follows:1) Bighead carp were injected i.p. with extracted microcystins (mainly MC-RR and–LR) at two doses, 400 and 1000μg kg-1 bw, and the changes in extractable MC in liver, in the histo- and ultra-structure of hepatocytes, and in serum biochemical parameters as well as biochemical responses of antioxidant and detoxification systems were studied at 1, 3, 12, 24 and 48 hr after injection. Quantitative and qualitative determinations of MC in the liver were conducted by HPLC...