Effect of nickel ions on ecotoxicological responses of the great ramshorn Planorbarius corneus allospecies (Mollusca: Gastropoda: Pulmonata: Planorbidae) of the Ukrainian river network

Abstract

This ecotoxicological study analyzed the impact of Ni2+ ions in different concentrations on the ecotoxicological and physiological features of the western and eastern vicariant allospecies of the great ramshorn superspecies Planorbarius corneus (Linnaeus, 1758) sensu lato in Ukrainian populations from rivers in two different nature-geographic zones: Forest (Polissia) and Forest-Steppe. The two allospecies differed from each other significantly (p≤0.05–0.001) in their responses to the main ecotoxicological indexes (LC0, LC50, LC100) in terms of the duration of the latent period, lethal time and mortality rate. By all these indices, the western allospecies had significantly more tolerance than the eastern allospecies. The same was true also for respiratory responses. Under the MPC (maximum permissible concentration) of Ni2+ ions in the environment, no changes were registered compared to the control. Increase in toxicant concentration up to 2 MPC was followed by increase in the rate, number, volume and duration of inspirations. At 3 MPC of Ni2+, however, the indices of direct diffusive respiration progressively decreased. In all measures, the western allospecies appeared better able to adjust to, and to survive increasing concentrations of Ni2+ than that from the east.