Food Web Impacts of the Invasive New Zealand Mudsnail in an Estuarine System
Non-indigenous species (hereafter NIS) have long been recognized as adversely affecting habitats they invade. While many of their documented ecological impacts have been to specific species, namely prey, they may impact whole food webs. Both vertebrate and invertebrate NIS have been present in the Columbia River since the mid 1800’s. The New Zealand mudsnail, (Potamopyrgus antipodarum, hereafter NZMS) was first reported in the Columbia River Estuary in 1995. This typically freshwater NIS invaded Youngs Bay, a shallow embayment within the Columbia River estuary system, and has proliferated within this benthic community. To date, there have been no inquiries into the impact of NZMS on the food web in a brackish water estuary within the United States. To identify community-level impacts by the invasive NZMS, an ecological census of the benthic communities of Youngs and Cathlamet Bays (reference site) was conducted, including comprehensive sampling of vertebrates and benthic invertebrates from these two brackish water systems. Stable isotope analysis (SIA) from these two systems is being utilized to identify trophic level food web relationships. 50% of one common estuarine fish, the Pacific staghorn sculpin (Leptocottus armatus) were found to contain NZMS in their guts. Furthermore, I have found densities reaching 15,711 snails/m² sampled. These results indicate NZMS in Youngs Bay may affect higher trophic levels.
Faculty Mentors: Valance Brenneis and Catherine deRivera