PHYSIOLOGY, PHYSICOCHEMISTRY AND METAL UPTAKE - A CRUSTACEAN PERSPECTIVE

The uptake of dissolved trace metals, such as zinc and cadmium, by cru staceans can often be explained in terms of physicochemical changes be yond the physiological control of the crustacean itself. Thus, uptake rates increase with dissolved metal concentration of exposure. Further more, at a given metal concentration, changes in uptake rates of zinc and cadmium can typically be explained by changes in the concentration (availability) of the hydrated free metal ion, for example as affecte d physicochemically by salinity change or the presence of metal-chelat ing agents. Nevertheless, some crustaceans appear able to counteract t o varying degrees such physicochemical effects by what appear to be ph ysiological responses, for example, to low salinity. Such responses va ry interspecifically, and cast light on the mechanisms of trace metal uptake by crustaceans.