Geospatial assessment of freshwater invasive species to inform turtle conservation and management

Identifying the ecological factors that determine the spread of invasive species is key to adequately managing endangered species in freshwater ecosystems. Invasive species are a main threat to turtles, which are targets of major conservation efforts worldwide. In freshwater ecosystems of the south-western USA, invasive bullfrog (Lithobates catesbeianus) and crayfish species (Faxonius virilis and Procambarus clarkii) represent a major risk to the desert mud turtle (Kinosternon sonoriense sonoriense), state-listed as a Species of Greatest Conservation Need in Arizona. As a species in the early stages of population decline, the desert mud turtle is a top candidate for the development of management plans to decrease extinction risk. An invasion risk assessment tool was built from available occurrence data for K. s. sonoriense and the invasive bullfrog and crayfish species in Arizona using 5,886 de-duplicated records from public databases and reports from the Arizona Game and Fish Department. The occurrence density of K. s. sonoriense was calculated state-wide to define populations in which the level of invasion by bullfrog and crayfish was assessed. The environmental factors associated with the abundance of invasive species in populations of K. s. sonoriense were then analysed. A higher prevalence of crayfish and bullfrog was detected in turtle populations located in perennial streams. Invasive abundance was significantly higher in turtle populations at higher elevation and closer to the main river trunk for both invasive taxa. Higher bullfrog abundance was detected near human settlements, whereas crayfish were more abundant further from human settlements. These results will inform which populations of K. s. sonoriense require intensive surveying and control of invasive species to maintain the health of native desert mud turtle populations. This study provides valuable information regarding the environmental conditions associated with the abundance of invasive species threatening turtle populations, helping to develop science-based management of freshwater ecosystems.

Automated summary

This study provides valuable information regarding the environmental conditions associated with the abundance of invasive species threatening turtle populations, helping to develop science-based management of freshwater ecosystems.