Effect of Cr (III) ions on respiration parameters of the allospecies of Planorbarius corneus s. L. (Mollusca, Gastropoda, Planorbidae) of the hydrological network of Ukraine

Abstract

The peculiarities of the influence of Cr (III) ions within the concentrations of 0.5 MPC to 3 MPC were studied on the indicators of pulmonary and direct diffuse respiration in snails of the “western” and “eastern” genetic vicariant allospecies of Planorbarius corneus s. lato in the hydrological network of Ukraine. These mollusсs, like all Pulmonata, have a bimodal respiration pattern. Oxygen is obtained by pulmonary respiration from the air, and by direct diffuse (surface) respiration from the water. Pulmonary respiration is performed with true lungs in both allospecies, while diffuse respiration is caused by the inflow of oxy­gen through the thin-walled cell membranes of the epithelial surfaces of their bodies into the cells of neighboring tissues. To P. corneus s. l., Cr (III) ions are an eхogenous toxicant of localized action with high cumulative properties. The presence of snails of both “western” and “eastern” allospecies in a contaminated Cr (III) medium was associated with the primary accumulation of this microelement in their hepatopancreas, followed by redistribution of the cumulant between other tissues and organs of the mollusсs poisoned due to the circulation of their liquid internal environment, the hаemolymph. At 0.5 MPC of Cr (III) in the environment containing the specimens of both allospecies, the parameters of their pulmonary and diffuse percutaneous respiration were in the range of normal values. That was the latent phase, the longest of all phases of the patholo­gical process of poisoning. The increase in the concentration of Cr (III) to the level of MPC, and then to 2 MPC was accompanied by an increase in the respiratory activity of mollusсs in response to the concentrations of involved toxicants, which corresponded to the phase of stimulation of the poisoning process. At 3 MPC Cr (III), there was a sharp drop in the values ​​of all studied parameters of both respiratory modes in the experimental animals to a level lower than the values ​​obtained for the control group. The values of studied parameters of both pulmonary and diffuse respiration were significantly lower for the snails of the “eas­tern” allospecies than for those for “western” allospecies at all used Cr (III) concentrations, This indicates a greater sensitivity and lesser tolerance of snails of the “eastern” allospecies to the action of the toxic factor under discussion.