Relative Abundance of Pond Snails in Turnbull National Wildlife Refuge, Washington, and the Spread of an Invasive Snail

Abstract

Abstract. Freshwater gastropods comprise a diverse and highly imperiled taxonomic group that is threatened by anthropogenic factors including the introduction of nonnative species. We surveyed 10 wetland ponds in Turnbull National Wildlife Refuge to assess the possible expansion of the nonnative European ear snail (Radix auricularia) and to determine the genus richness and relative abundance of native gastropods. D-frame dip nets were used to sample gastropods at 4 locations in each pond. Six genera of gastropods were found, including R. auricularia in 6 ponds where it was not previously known. Radix auricularia is now the dominant genus in Middle Pine and Lower Pine Lakes, with relative abundances of 84.13% and 92.31%, respectively. Due to the high abundance and spread of R. auricularia in Turnbull National Wildlife Refuge, resource managers need to investigate the snail's impacts and implement strategies to reduce possible negative effects of this nonnative snail on native gastropods and other wildlife.