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 b urden with body weight were examined. The accumulation of soft tissue zinc in the American oyster (Crassostrea virginica) was related to tim e integration of uptake. Short term uptake of Zn-65 was measured in th e laboratory. It was (i) a function of the (dry soft-tissue) weight of the oyster, (ii) inversely related to the salinity of the ambient wat er, 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 pow ers for Zn-65 uptake when b was adjusted for the oyster-bed salinities . The soft-tissue zinc concentration (y/W) of an oyster increased cont inuously, but the rate of the increase was reduced as the oyster grows larger. Both short-term uptake and in-situ body burden varied with sa linity. The soft-tissue zinc concentrations of hooked mussels (Ischadi um recurvum) from the Rappahannock River oyster beds, contrary to the oysters, appeared to be in equilibrium with ambient concentrations.