WEIGHT AND SALINITY EFFECTS ON ZINC UPTAKE AND ACCUMULATION FOR THE AMERICAN OYSTER (CRASSOSTREA-VIRGINICA GMELIN)

The power relationships of short-term net uptake and Of in-situ body burden with body weight were examined. The accumulation of soft tissue zinc in the American oyster (Crassostrea virginica) was related to time integration of uptake. Short term uptake of Zn-65 was measured in the laboratory. It was (i) a function of the (dry soft-tissue) weight of the oyster, (ii) inversely related to the salinity of the ambient water, and (iii) increased linearly with ambient concentrations. When in-situ soft-tissue zinc body burdens of oysters from the James River and the Rappahannock River were fit to power functions of body weights (y = aW(b)), the values of b for all sites were larger by 1 than the powers for Zn-65 uptake when b was adjusted for the oyster-bed salinities. The soft-tissue zinc concentration (y/W) of an oyster increased continuously, but the rate of the increase was reduced as the oyster grows larger. Both short-term uptake and in-situ body burden varied with salinity. The soft-tissue zinc concentrations of hooked mussels (Ischadium recurvum) from the Rappahannock River oyster beds, contrary to the oysters, appeared to be in equilibrium with ambient concentrations.