Survey of Parasites of Freshwater Snails

The ITI-funded survey of freshwater snails and their parasites aims at (i) identifying freshwater-snail-infecting parasites in Israel using comparative morphology and molecular techniques, and (ii) surveying both indigenous and introduced freshwater gastropods. It is partly driven by the invasion and establishment in Israel of two freshwater snails, Tarebia granifera and Thiara scabra, which may serve as intermediate hosts of parasitic trematodes that cause diseases in humans and livestock, as well as by the recent emergence in several fish farms in the Beit She'an Valley of a trematode previously found in an aquarium harboring tropical fish. Parasites play a vital role in the maintenance and regulation of biodiversity, both through their hosts and via other free living species that rely on these hosts. Invading parasites and the infectious diseases they transmit have also become a major threat to wildlife conservation and endangered species, by influencing host genetic diversity and altering species composition. Although comprehensive databases of indigenous and non-indigenous freshwater gastropods of Israel have been compiled recently, knowledge of their parasites and how they interact with native vs. introduced snails is still lagging behind. This lack of knowledge stands in striking contrast with important public health and agricultural implications of snail-infecting parasites in freshwater bodies in Israel, because adult stages of many trematodes are non-fastidious in their choice of definitive hosts. Introduced gastropods can aggravate the situation either by transmitting invasive pathogens or through increased resistance to native parasites which allows them to outcompete native snails. Ultimately this study will serve as a basis for future research in conservation biology that may improve our current understanding of the players affecting freshwater gastropod fauna in Israel and assist in developing effective eradication and containment schemes to the benefit of agriculture and public health.