Aspects of osmoregulation in the amphipod Gammarus duebeni : the effects of changing salinity and some potential pollutants

Dawson, Michael Ellis (1982) Aspects of osmoregulation in the amphipod Gammarus duebeni : the effects of changing salinity and some potential pollutants. University of Southampton, Doctoral Thesis.

Abstract

Water and sodium fluxes have been investigated in the euryhelineamphipod Gammarus duebeni (Lilljeborg) in conditions of constant and changing salinity. The effects of some potential pollutants upon osmoregulatory mechanisms have been considered. It appears that G. duebeni is capable of large and rapid (4 minute) changes in apparent permeability in response to salinity fluctuations and that these changes are invariably appropriate to osmoregulatory requirements. Alterations in apparent permeability over the course of long term acclimation to high and low salinities are considered with respect to changes in the fatty acid composition of the gill lipids. Further, lipophilic contaminants are concentrated in the gills and their presence is coincident with changes in lipid composition. Exposure to mercury, cadmium and particularly copper interferes with apparent permeability. Alterations in the rate of sodium uptake approach completion within four hours of sudden salinity changes and occur cyclically in a cycling salinity regime. The presence of mercury reduces sodium uptake as medium salinity falls. This metal depresses the total body sodium concentration of animals in dilute media and totally inhibits gill Na+E+ ATPase activity in Vitro. Mercury also induces diuresis in G. duebeni following transfer from 2% to 100% SW. The findings are discussed in relation to the ecology of the species. Notes are appended on the use of a microprocessor to control experimental fluctuations of environmental variables, specifically salinity.

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