Effects of an Invasive Snail (Melanoides Tuberculata) on Native Invertebrate Abundance and Diversity, The

Invasive species can often displace native species in an ecosystem by competing for the same resources. Melanoides tuberculata, an exotic gastropod snail native to Asia, has invaded and established a population in Kelly Warm Springs, Grand Teton National Park, Wyoming. Invasive populations of Melanoides are closely linked with the aquarium trade and are limited to warm fresh waters. Benthic macroinvertebrates were sampled pre- and post-invasion from six random sites along a 500 meter reach. Invertebrates known to be in the stream at present include: Chironomidae, Trichoptera, Helicopsychidae Cheumatopsyche, Helicopsychidae helicopsyche, Planorbidae, Byralus Torquis parvus, Physidae, Lymnaeidae Fossaria, Caenidae, Hyallela azteca, and Oligiochaeta. Preliminary data suggests there has been a decline in the density and biomass of native invertebrates since the Melanoides invasion after 2001. By 2007, Melanoides biomass was 58 g AFDM m-2. By comparison, the biomass of HyallelaI was 1 g AFDM m-2 in 2007 and the biomass of Chironomidae was 0.3 g AFDM m-2 in 2007. Hayllela and Chironomidae biomass decreased by approximately 6% and 31%, respectively, from 2001 to 2007. This decline in non-Melanoides invertebrate biomass is likely to impact all other parts of the stream food web.