Historical changes and current status of crayfish diversity and distribution in the Laurentian Great Lakes

Environmental DNA (eDNA) detects the invasive crayfishes Orconectes rusticus and Pacifastacus leniusculus in large lakes of North America

“…These sites included the two largest natural lakes in California (Lake Tahoe and Clear Lake), as well as a series of smaller lakes and reservoirs (Electronic Supplementary Table S3). We sampled from seven locations around the perimeter of Lake Tahoe and from both the southern and western Table S3), whether or not O. rusticus or P. leniusculus eDNA was detected at a site, and historic localities for O. rusticus within the Great Lakes from Peters et al (2014) shoreline of Clear Lake, whereas most other study sites-regardless of region-had all replicated eDNA samples (below) taken from close proximity (within *100 m) to a single location on their shoreline. Lake Tahoe in particular was chosen because of its history as a source for invasive P. leniusculus populations shipped to Europe (Larson & Williams, 2015), capacity to serve as a western North American surrogate for the Great Lakes in a cross-continental comparison, and finally for the availability of recent monitoring of P. leniusculus relative abundance throughout this lake (and some of its neighbors) for comparison to our eDNA results.…”

“…However, in both study regions, we had access to resources that could be used to relate eDNA results to either best available estimates of species distributions or recent measures of absence and relative abundance. First, Peters et al (2014) recently summarized all known crayfish presence localities throughout the Great Lakes, using a combination of published academic and unpublished grey literature and government agency monitoring records (Fig. 1) Fig.…”

“…As examples, the performance of eDNA for benthic arthropods like freshwater crayfish has been equivocal between initial studies (e.g., Tréguier et al, 2014;Figiel & Bohn, 2015;Dougherty et al, 2016), and tests of eDNA in the largest of freshwater habitats like the Laurentian Great Lakes of the United States (US) and Canada (hereafter Great Lakes) have been relatively rare (but see Tucker et al, 2016). Given that organisms like crayfish have invaded and negatively affected large freshwater habitats including the Great Lakes (Peters et al, 2014), we ask: is it feasible to provide early detection of invasive benthic arthropods in massive freshwater lakes using eDNA? We addressed this question by developing and applying eDNA assays for two major invasive crayfishes in large lakes of their reciprocal non-native ranges in North America.…”

“…O. rusticus is native to the Ohio River drainage in the US, but was introduced northward through pathways including live bait use by anglers into the Great Lakes, as well as inland lakes and rivers of US states and Canadian provinces like Wisconsin and Ontario (Capelli & Magnuson, 1983;Edwards et al, 2009;Peters et al, 2014). More recently, O. rusticus has established its first populations in western North America (e.g., Olden et al, 2009), and species distribution modeling suggests that more of the western US is likely vulnerable to further invasion by O. rusticus (Morehouse & Tobler, 2013).…”

“…We also used citizen scientists in affiliation with public zoo and aquarium summer science programs to collect some water samples from the Great Lakes region. Finally, we compared eDNA detections for O. rusticus to recent distributional records for this species from a comprehensive review of crayfish across the Great Lakes (Peters et al, 2014), and compared eDNA detections for P. leniusculus to results of baited trapping for this species in a subset of the California and Nevada lakes. Cumulatively, our multi-region study tested whether eDNA can successfully detect invasive benthic arthropods from large lake habitats while screening for new potential crayfish invasions across the North American continent.…”