Temperature is a major environmental factor that influences all aquatic organisms. Our objective was to expose individuals of Lymnaea stagnalis from an Eastern Siberian population to wide temperature gradients to determine whether they express a thermal stress response and what mechanisms are involved in this process. Several parameters of the cellular mechanisms of thermal resistance were tested under the experimental conditions: the level of lipid peroxidation, the synthesis of heat shock protein HSP70, the activities of antioxidative enzymes and changes in the content of energy-associated metabolites.
The results of this study show that the temperature at which the cellular and biochemical stress-response is activated in the L. stagnalis from Eastern Siberian lakes directly corresponds to environmental temperature within the range of 3 to 15°C. The exposure of the gastropods to temperatures outside this range resulted in the activation of HSP70 synthesis, changes in the activities of antioxidative enzymes and glycogenic metabolism. These conditions can be considered to be stressful to the tested gastropods. Because L. stagnalis is a common species that inhabits a wide range of lakes with temperatures higher than 15°C, we suggest that the limitation established by this study can be considered to be the result of a local temperature adaption of the Eastern Siberian population. This diversity of temperature adaptation among different populations of L. stagnalis contributes to the common environmental variation and plasticity of the species, which is strongly reflected at the levels of cellular and biochemical processes and the gastropods' stress reactions.