The effect of digenea larvae on calcium content in the shells of Lymnaea stagnalis (L.) individuals.

The objective of this work was to examine the calcium concentration in the shells of naturally infected individuals of Lymnaea stagnalis. Calcium concentration in the water of lakes and in snail shells was examined by the EDTA method. Calcium concentration in the shells of infected snails was found to be higher than that in the shells of uninfected ones only in the lake with the lowest calcium concentration in water. However, this difference is not evidence of hypercalcification of snail shells caused by trematode larvae but suggests that the limited calcium concentration in the environment can be a very good factor for studying snail shell calcification under natural conditions. Moreover, small adult snails from 2 lakes had more calcium in their shells than did large ones. Different reproductive rates of different-sized snails could be the cause of this phenomenon.