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Abstract - North American crayfish biodiversity is in need of conservation attention, which requires monitoring to assess the status of potentially imperiled species. Pennsylvania has a long history of crayfish studies, dating back to the early 1900s and continuing today. We sampled 37 new and historical sites in southeastern Pennsylvania in an effort to locate remnant populations of Cambarus diogenes (Devil Crayfish), an ecologically important burrowing crayfish. While we did not find Devil Crayfish at any historical sites, we discovered a single population in Neshaminy State Park, indicating a decline in this species' range in Pennsylvania since the last survey, circa 1905. We attribute the statewide decline of Devil Crayfish to an inherently limited amount of suitable habitat, urbanization, and biological invasions, and recommend that steps be taken to protect this species.
Introduction
North American freshwater biodiversity has decreased at an alarming rate since the beginning of the 20th century (Burkhead 2012, Ricciardi and Rasmussen 1999). Among North American freshwater organisms facing the greatest threats are crayfishes, of which 32% (127 of 391) are considered endangered or vulnerable by the American Fisheries Society Endangered Species Crayfish Subcommittee (C.A. Taylor, Illinois Natural History Survey, Champaign, IL, pers. comm.; Taylor et al. 2007). Recent research has elucidated major threats to freshwater crayfish biodiversity, including but not limited to climate change, habitat loss/alteration, and biological invasions (Bland 2017, Richman et al. 2015). However, very few North American crayfish species have been the focus of the types of detailed studies necessary to inform conservation assessments, leading to an underrepresentation of crayfishes on the federal Endangered Species list (Moore et al. 2013, Richman et al. 2015).
Pennsylvania has a long history of crayfish research, starting with the work of naturalist and Carnegie Museum of Natural History Curator Arnold E. Ortmann in the early 1900s (Ortmann 1905, 1906). More recently, substantial resources have been devoted to crayfish surveys aimed at quantifying trends in the ranges of Pennsylvania crayfishes over the last century (Lieb et al. 2008, 2011a, 2011b; Loughman et al. 2017, 2018). These surveys have led to recommendations for management actions, as well as 2 new state species records (Cambarus acuminatus Faxon [Acuminate Crayfish] [Lieb et al. 2008]; Creaserinus fodiens [Cottle] [Digger Crayfish] [Loughman et al. 2018]), highlighting the...