Effects of various larval digeneans on the calcium carbonate content of the shells of Helisoma trivolvis, Biomphalaria glabrata, and Physa sp.

The calcium carbonate concentrations in the shells of Helisoma trivolvis and Physa sp. naturally infected with larval trematodes and Biomphalaria glabrata experimentally infected with larval trematodes were analyzed quantitatively. The larval trematode-snail relationships studied were H. trivolvis infected with larval Echinostoma trivolvis and Physa sp. infected with various larval digeneans, and B. glabrata infected with Echinostoma caproni or Schistosoma mansoni. The calcium carbonate concentrations of the shells of infected snails and uninfected cohorts and of the water in which the snails were maintained were determined by ion exchange chromatography. No significant differences in the calcium carbonate concentrations of shells of infected versus uninfected snails were found. The shells of B. glabrata infected with E. caproni contained significantly less calcium carbonate than the shells of uninfected B. glabrata. The hypercalcification hypothesis, i.e., larval trematodes induce an increase in the calcium concentrations in the shells of their snail hosts, was not upheld in any of the snail-larval digenean systems studied herein.