Project Title: Larval behavior, Dispersal, and Connectivity of Estuarine Trematode Parasites

Date: 6/2019-8/2022

Principal Investigator(s): Lauren Dykman

Affiliations: Woods Hole Oceanographic Institution

Summary: Trematodes are abundant parasites that significantly influence community structure and energy flow in estuarine ecosystems. Their effects on hosts include behavioral modification, castration, tissue degradation, and mortality. Trematodes are also important indicators of ecosystem health, because their indirect life cycles (which require two to three hosts) depend upon a diverse and healthy community. The indirect life cycles of trematodes also include two free-living, host-seeking larval stages. The swimming behaviors of these stages, and the environmental conditions that influence them, are critical factors that determine a parasite’s ability to maintain connectivity between hosts.

In New England estuaries, nine trematode species parasitize the abundant Eastern Mudsnail (Tritia obsoleta) as a first intermediate host. Trematodes disperse from the snail as swimming or crawling larvae called cercariae. Cercariae target many species from various taxa as their second intermediate host, including fish, bivalves, and worms. Some life cycles of these trematode species have been described in laboratory studies, but the dispersal potential, transmission dynamics, and infectivity of cercariae to second intermediate hosts in the wild are largely unknown. My project uses a combination of field and laboratory experiments to understand how larval behavior, host distribution, and features of the estuarine environment determine when and where infection occurs. In particular, I will use bivalves in aquaculture as focal host species for their importance to the ecology, culture, and economy of New England. The aim of this research is to provide a mechanistic understanding of how larval behavior and the environment contribute to parasite connectivity, and apply this understanding to assessing risk in different aquaculture systems.