Parasitological assessment of gastropods In Taal Lake, Batangas

Abstract

Freshwater gastropods serve an important role in the transmission of diseases, as they may become an intermediate, paratenic, or definitive host of parasites. Previous studies in the Philippines described the diversity of freshwater gastropods. However, limited literature investigated the presence of parasites among these snails. This study assessed the gastropod diversity and the presence of parasites among the gastropods in Taal Lake. Eighteen out of 336 snails were infected – a prevalence of 5.36% was calculated. Tarebia granifera (Family Thiaridae), a taxa-displacing species, was observed to dominate across all the sites surveyed. The high density of the T. granifera may be responsible for the low occurrence of the Melanoides species. T. granifera was the most abundant and common host for coarsely annulated nematode, sporocysts, leptocercous cercaria, and furcocercous cercaria. Pomacea canaliculata was observed to harbor arthropods such as midge larva, carabiform larva, and crustaceans. The two Thiara sp. were also observed to harbor a crustacean and a midge larva. A significant association (p < 0.05) between the snail host species and status of infection was observed. The Talisay area exhibited high snail host diversity and species richness. On the other hand, the west side of the Taal Island, characterized by calmer waters and abundant vegetation, exhibited high snail host dominance, and high parasite diversity and richness. A significant difference on the Simpson’s Dominance index between the snail hosts and parasites was observed. However, no significant differences were observed among the other indices across the sites and between the host and parasites.