Chemotoxical effect of the cesium stable isotope on embryogenesis and post embryonic growth of pond snail Lymnaea stagnalis (Gastropoda, Pulmonata)

The stable caesium isotope in high concentrations (5 maximum permissible concentrations, MPC) has an lethal influence upon the embryonic development in L. stagnalis. At lower concentrations (0,5 and 1 MPC) survival of embryos in egg massed of specimen from water bodies high levels of radioactive and chemical contamination (the Perstok Lake in Chernobyl nuclear disaster zone and warm effluent channel of Bereza electric power plant) is higher than in those from relatively pure Pripyat River and meliorative channel. Significant differences in growth rates in specimen emerged from these egg masses are absent. (authors)