Occurrence of cercariae in a permanent pond and stream

Abstract

This investigation deals with the occurrence of cercariae in a permanent pond in contrast to those occurred in a stream. The snails were hand collected and microscopically observed for the emergence of cercariae in the laboratory. Temperature and the dissolved oxygen content of the water were recorded for the observation of their effect on the occurrence of cercariae. Current of the stream and the chemical content of the water were also recorded for the same purpose. In general five types of cercaria were found. Three belonged to the group Furcocercus and two belonged to the group Xiphidiocercus. Only one cercariae ornatae cercaria, was common in both sites and was the only one present in the stream. It appears that the host specificity of the cercariae and the current of the stream are the two main factors contributing to the occurrence of the cercariae in the two environments.