Applying new aquatic habitat data to manage invasive and imperiled crayfishes in North America

North America is home to the majority of the world’s crayfish diversity, but many of these crayfishes are considered invasive, and an even greater number are highly imperiled and at risk for extinction. In addition, new GIS data layers developed specifically for freshwater have recently been developed in order to better characterize freshwater habitat in modeling applications. My research applies these new freshwater GIS data layers to species distribution modeling (SDM) with implications for management of both imperiled and invasive freshwater crayfishes. In Chapter 2, I developed SDMs to anticipate the potential future range extent of the emerging invasive crayfish Procambarus clarkii in the Laurentian Great Lakes. I created an SDM of all suitable crayfish habitat across the Great Lakes, then constrained this habitat to areas anticipated to be suitable for P. clarkii based on known physiological limitations of this species. These predictions of where P. clarkii is likely to establish populations can be used to identify areas where education, outreach, compliance, and law enforcement efforts should seek to prevent new introductions of this crayfish and help prioritize locations for surveillance aimed at detecting newly established populations. In Chapter 3, I developed SDMs using global freshwater GIS layers and historical occurrence records to characterize the distributions and habitat associations for Pacifastacus connectens and Pacifastacus gambelii, two data-deficient crayfish species native to the western United States. I then compared these SDM predictions to results of contemporary field sampling and found that these crayfishes have seemingly experienced substantial range declines, attributable to apparent displacement by invasive crayfishes and impairment or change to stream communities and habitat. I recommend increased conservation and management attention to P. connectens and P. gambelii in response to these findings. Together, these two studies will be among the first to apply new freshwater-specific habitat data to modeling the distributions of imperiled and invasive species and may be useful in providing management guidance in both freshwater systems