Comparative mortality studies on Biomphalaria glabrata (mollusca: Pulmonata) exposed to copper internally and externally

Abstract

Various concentrations of copper in the form of CuSO 4 were injected into the hemocoel of Biomphalaria glabrata, and mortality of this snail was subsequently monitored. The concentrations of copper in the hemolymph of injected snails were calculated, and specimens were incubated in these concentrations. Greater mortality was observed when snails were incubated in concentrations of copper than when they were injected with a sufficient amount of copper to attain these same concentrations in the hemolymph. Injection of copper into the hemocoel of B. glabrata resulted in the formation of a noncellular hemolymph precipitate, most likely denatured proteins, at the injection site, which was most noticeable with higher concentrations of copper. It has been concluded that external concentrations of copper are more cidal to B. glabrata than are internal, i.e., injected, concentrations. These data support the hypothesis that the cidal action of copper on B. glabrata is due to an attack on the mollusc's surface epithelia.