A laboratory-based comparison of osmoregulatory ability at different water temperatures and salinities in the stenothermic isopod Saduria entomon (Linnaeus, 1758) and the eurythermic amphipod Corophium volutator (Pallas, 1766) from the Baltic Sea

The aim of the investigation was a comparison of osmoregulatory ability at different water temperatures and salinities by the stenothermic isopod Saduria entomon (Linnaeus, 1758) and the eurythermic amphipod Corophium volutator (Pallas, 1766) from the Baltic Sea. The experiments were performed under laboratory conditions at different water temperatures (5, 10 and 15?°C) and salinities (3, 6.6, 15 and 25 PSU for S. entomon and 3, 6.3, 15 and 25 PSU for C. volutator). The osmotic concentrations of the crustaceans’ haemolymph were determined using the melting point method. Temperature had a statistically significant effect on the osmoregulation in S. entomon, but had generally no statistical influence on the osmoregulation in C. volutator. This physiological information regarding adaptation provides a basis for predicting the distribution of these species in changing environments. The implications of the results for the comparative adaptability of the two species are considered.