Does the environment or the source of the population define stress status and energy supply in the freshwater amphipod, Gammarus fossarum?

To investigate the effects of acclimation and/or adaptation on the stress protein (hsc/hsp70) response, adenylate energy charge (ACE), ATP/ADP ratio and both lipid and glycogen supply, specimens of four different populations of the freshwater amphipod Gammarus fossarum (Koch, 1835) were transplanted and exposed at sites with various levels of pollution. Induction of the stress protein response was highest in those gammarids transplanted from nearly unpolluted or just moderately polluted sites to severely polluted stream portions. The lowest hsc/hsp70 levels were found in animals transplanted from the polluted sites to the less polluted sites. In all cases the adenylic energy charge (AEC) and ATP/ADP ratio did not show any deficiency in the cellular energy supply. The amount of energy storage substrates, lipid droplets and glycogen in the hepatopancreas, the main metabolic tissue, was similar in all resident populations. In all these amphipod populations, tolerant phenotypes which had diverged genetically were not revealed; rather, the stress and recovery effects derived from the physiologically regulated, cellular stress response.