Determining the Presence of the Invasive Rusty Crayfish (Faxonius rusticus) in Erie County Utilizing a GIS Model

Abstract:

The rusty crayfish (Faxonius rusticus) is an invasive species that has been found at Presque Isle State Park in Erie County, PA; however, it was previously unknown whether F. rusticus existed in the county beyond Lake Erie. Previous studies have shown that F. rusticus has destructive impacts upon the ecosystems that it invades and poses a significant to certain native species. Given the negative effects of F. rusticus invasion, the aim of this study was to determine their extent in Erie’s aquatic ecosystems and to predict which of Erie’s waterways might be most vulnerable to future introductions. Previous F. rusticus suitability models have focused on the large (country/state) scale, utilizing either bioclimatic variables or site characteristics as suitability factors. The objective of this study was to 1) generate a county-level Geographic Information System (GIS) model using ArcMap and R/MaxENT which integrates the bioclimatic and site-specific environmental factor approaches; 2) conduct a suitability analysis to predict the presence or absence of F. rusticus in Erie County; and 3) to validate the GIS model by sampling lakes and streams within Erie County for the presence or absence of F. rusticus. Sixteen candidate sites were evaluated for water and habitat quality parameters. The sites were sampled by hand, kick net, and traps. The species, sex, and carapace length of each individual crayfish were recorded. A MaxENT model was produced in R to assess the bioclimatic suitability of the candidate sites; bioclimatic suitability was then considered alongside water and habitat quality factors to produce an integrated model in ArcMap. Model validation is ongoing, and results will be discussed further in an oral presentation at the Sigma Xi Undergraduate Research Conference. It is anticipated that the most important factors in predicting the occurrence of Faxonius crayfish will be instream cover and cobble substrate. It appears that the distribution of F. rusticus in Erie County is currently limited to Presque Isle State Park, but the occurrence of other Faxonius crayfishes in the county’s waterways suggests that these areas may be vulnerable to rusty crayfish invasion if additional introductions were to occur. As such, the findings of this study can be used to inform invasive species control efforts in the region.