GROWTH, FECUNDITY AND GLYCOGEN UTILIZATION IN LYMNAEA-PALUSTRIS EXPOSED TO ATRAZINE AND HEXACHLOROBENZENE IN FRESH-WATER MESOCOSMS

Freshwater mesocosms were used to study the long-term sublethal effect s of atrazine and hexachlorobenzene (HCB) on a basommatophoran gastrop od, Lymnaea palustris (Muller). Growth, fecundity, and biochemical par ameters related to polysaccharide metabolism (glycogen content and pol ysaccharide-hydrolyzing enzyme activity) of pesticide-exposed snails w ere compared with those of control animals maintained in untreated mes ocosms. HCB inhibited body growth and stimulated egg production, where as atrazine had no relevant effect on these physiological parameters. Also, HCB stimulated the activity of polysaccharide-hydrolyzing enzyme s, suggesting that changes in the metabolism of reserve polysaccharide s (glycogen) may be involved in the inhibition of growth and increase of fecundity. In contrast, atrazine had no effect on the metabolism of polysaccharides. It is concluded that the effects of HCB are related to its neurotoxicity that would have affected the neurohormonal contro l of growth and reproduction of exposed snails. It is suggested that p olysaccharide-hydrolyzing enzymes may be used as biomarkers to predict the effects of neurotoxic pesticides on freshwater snail populations.