Parasitic Trematode Prevalence within Eastern Mudsnails (Ilyanassa Obsoleta) in the Delaware Bay

• Seth Buchanan, Marine Science, University of Delaware

• Edward Hale, School of Marine Science and Policy, University of Delaware

Parasitic trematodes are an abundant and ecologically important group of flatworms that rely on complex life cycles involving multiple host species. Environmental conditions and host availability influence trematode transmission. Determining patterns of infection may provide valuable insight into trophic interactions and coastal ecosystem functioning. The Eastern Mudsnail (Ilyanassa obsoleta) is a common gastropod found in the Delaware Bay, which contributes to nutrient recycling, bioturbation, and energy transfer within estuarine food webs. Although numerous trematode species have been documented infecting mudsnails throughout the Delaware Bay, the diversity and prevalence of these parasites remain understudied. This research investigated the extent of trematode infection in Eastern Mudsnail collected from three unique locations in Delaware Bay (DE, U.S.): Slaughter Beach, The Great Marsh in Lewes, DE, and Cape Henlopen State Park. Mudsnails were collected during low tide through randomized quadrat sampling, and specimens were retained for further laboratory analyses. Heat-induced shedding was used to stimulate the emergence of trematodes, and water from each container was examined microscopically to determine the presence of the free-swimming larval stage, cercariae. Trematoda cercariae were found within snails at each sampling location; their presence indicates ecological and food-web complexity. Mudsnail abundance was greatest at the Marsh, while Slaughter Beach had very little abundance, despite having a suitable substrate composition. Cape Henlopen exhibited the highest relative trematode infection (53.33%), whereas Slaughter Beach had low relative confirmed infection (25%). We can’t infer one being healthier than the other, but it does highlight that Cape Henlopen has greater biodiversity. Improved knowledge of these interactions may strengthen the use of trematodes as biological indicators for monitoring environmental change, biodiversity, and the ecological condition of the Delaware Bay.