Studies on the Salinity Tolerance of two Pulmonate Snails (Bulinus Truncatus and Biomphalaria Pfeifferi), Intermediate Hosts of Schistosoma Species

Abstract

Bulinus truncatus and Biomphalariapfeifferi were cultured in varying concentrations ofseawater to study the effect of salinity on the survival and growth of adults and juveniles. The eggs were investigated for their hatchability. The experiment was conducted over a period of seven weeks for the snails while the eggs were studied over a two week period. Daily and weekly percentage mortality were determined. Weekly changes in weight and shell length was determined and used as an index of growth. Eggs of the snails were in culture medium for a minimum of two weeks. Salinity affected the mortality of the snails (i.e. high salinities caused high mortalities of the snails). Salinities of 3.5% to 1.7% did not significantly affect weight but significantly affected shell length, (i.e. the snails increased in shell length). Salinity affected the hatching ability of the eggs of the snails. The higher the salinity, the lower the hatchability of eggs.