NA+,K+-ATPASE ACTIVITY IN THE GILLS OF THE FLOUNDER (PLATICHTHYS-FLESUS) IN RELATION TO MERCURY CONTAMINATION IN THE FIRTH-OF-FORTH

Branchial Na+,K+-ATPase activity has been shown to be affected by a variety of environmental contaminants although few studies have been carried out in the field along defined contaminant gradients. In this work Na+,K+-ATPase was measured in gill homogenates from flounder (Platichthys flesus) caught at sites within the Firth of Forth contaminated with a variety of industrial effluents and from a comparatively uncontaminated adjacent estuary which served as a control site. Enzyme activity was lower in gills from the more contaminated sites and there was a strong correlation between the mercury contamination of the flesh and Na+,K+-ATPase in the gill. The results are discussed in relation to effects of contaminants on osmotic and ionic regulation in fish.