The parasite Parelaphostrongylus tenuis is commonly found in white-tailed deer (Odocoileus virginianus) in the Adirondack Mountains, NY. Deer are asymptomatic; the parasite passes through their digestive system into their feces, where gastropods can become infected. Moose that accidentally ingest infected gastropods while browsing can develop neurological disorders that are often fatal. We investigated absolute abundance of gastropods using capture-recapture sampling and identified the species that carry the parasite P. tenuis. Eight sampling sites were chosen using a stratified random sample based upon an existing index of moose density. Each site consisted of three 1000m survey segments. On each segment we sampled a plot consisting of sixteen 35.6 cm x 27.9 cm cardboard sheets in a 4x4 grid. At each visit, snails found on/under cardboard were given a unique mark with nail varnish. We estimated absolute abundance of snails at each site using two models; time varying detection probability (p) and constant p. On the last visits, all gastropods found were collected and sent to the Cornell University Animal Health and Diagnostic Center to identify which were infected.
Results/Conclusions
We marked 41 snails and recaptured 12 over the 24 grids surveyed. The estimated absolute abundance of snails for a site with low predicted moose density was 22.51 individuals with a 95% CI [17.65, 33.62]. The estimated absolute abundance for a medium moose density site was 1.73 individuals with a 95% CI [1.36, 2.59]. The estimated absolute abundance for a high moose density site was 10.39 individuals with a 95% CI [8.15, 15.52]. There was no significant relationship between snail abundance and the index of moose abundance at the sites. Upon receiving the data regarding prevalence of P. tenuis infection in our collected gastropods, we will identify the areas that these infected gastropods reside and examine the relationship with moose density to help identify areas where moose are more likely to come in contact with the parasite.