Dose-dependent effects of extracted microcystins on embryonic development, larval growth and histopathological changes of southern catfish (Silurus meridionalis).

Abstract

A laboratory toxic experiment was conducted to examine dose-dependent effects of extracted microcystins (MCs) on embryonic development, larval growth and histopathological changes of southern catfish (Silurus meridionalis). Fertilized eggs were incubated in solutions with four concentrations of MCs (0, 1, 10, 100 microg MC-L Req l(-1)). Higher MCs retarded egg development (2-10h delays) and larval growth, reduced hatching rate (up to 45%), and caused high malformation rate (up to 15%) and hepatocytes damage (characterized by disorganization of cell structure and a loss of adherence between hepatocytes, cellular degeneration with vacuolar hepatocytes and marginal nuclei, even hepatocellular necrosis). A 10 microg MC-L Req l(-1) is close to a high concentration in natural cyanobacterial blooms, suggesting a possible existence of such toxic effects in eutrophic waters.