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Greater Yellowstone Ecosystem Report

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Understanding invasive species impacts is critical to determining how an ecosystem may function after an introduction. Invasive species can alter the structure and function of ecosystems, reduce biological diversity, and alter communities through predation, facilitation and competition. In the past 30 years, the invasive New Zealand mud snail (Potamopyrgus antipodarum) has established in areas of conservation concern in the American West including Yellowstone National Park. To develop a greater understanding of the impact of P. antipodarum on the native co-occurring snail, Fossaria (Bakerilymnaea) bulimoides group, we conducted two experiments to assess the interactions occurring between these snails. We found that F. bulimoides growth was reduced by all interactors, but especially by P. antipodarum. In addition, growth of F. bulimoides was much more affected by high biomass of snails than P. antipodarum. P. antipodarum grew more in the presence of interactors and their growth was facilitated by the presence of the native snail F. bulimoides.