TY - JOUR
T1 - Distribution, habitat associations, and conservation status updates for the pilose crayfish Pacifastacus gambelii (Girard, 1852) and Snake River pilose crayfish Pacifastacus connectens (Faxon, 1914) of the western United States
AU - Egly, Rachel M.
AU - Larson, Eric R.
N1 - Funding Information:
Bronwyn Williams (NCSM) and Patricia Weaver (NCSM) aided with field sampling and data compilation. This manuscript was improved by comments from Mark E. Hay, Göran Klobučar, Zachary J. Loughman, Cory D. Suski, Christopher A. Taylor, and an anonymous reviewer. Rachel M Egly was funded by a research assistantship from the University of Illinois Department of Natural Resources and Environmental Sciences. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The following grant information was disclosed by the authors: University of Illinois Department of Natural Resources and Environmental Sciences.
Funding Information:
Rachel M Egly was funded by a research assistantship from the University of Illinois Department of Natural Resources and Environmental Sciences. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Publisher Copyright:
Copyright 2018 Egly and Larson.
PY - 2018
Y1 - 2018
N2 - Our study evaluates the distribution, habitat associations, and current conservation status of the Snake River pilose crayfish Pacifastacus connectens (Faxon, 1914) and pilose crayfish Pacifastacus gambelii (Girard, 1852), two little-studied and data-deficient species endemic to the western United States. We first developed a species distribution model (SDM) for the pilose crayfishes based on their historical occurrence records using boosted regression trees and freshwater GIS data layers. We then sampled 163 sites in the summers of 2016 and 2017 within the distribution of these crayfishes, including 50 where these species were observed historically. We next compared our field results to modeled predictions of suitable habitat from the SDM. Our SDM predicted 73 sites (45%) we sampled as suitable for the pilose crayfishes, with a moderate AUC value of 0.824. The pilose crayfishes were generally predicted to occur in larger streams and rivers with less extreme upstream temperature and precipitation seasonality. We found the pilose crayfishes at only 20 (12%) of the 163 total sites we sampled, 14 (20%) of the 73 sites predicted as suitable for them by our SDM, and 12 (24%) of 50 historical sites that we sampled. We found the invasive virile crayfish Faxonius virilis (Hagen, 1870) at 22 sites total and 12 (24%) historical sites for the pilose crayfishes, and we found the "native invader" signal crayfish Pacifastacus leniusculus (Dana, 1852) at 29 sites total and 6 (12%) historical sites for the pilose crayfishes. We subsequently used a single classification tree to identify factors associated with our high rate of false positives for contemporary pilose crayfish distributions relative to our SDM. This classification tree identified the presence of invasive crayfishes, impairment of the benthic community, and sampling method as some of the factors differentiating false positives relative to true positives for the pilose crayfishes. Our study identified the historical distribution and habitat associations for P. connectens and P. gambelii using an SDM and contrasted this prediction to results of contemporary field sampling. We found that the pilose crayfishes have seemingly experienced substantial range declines, attributable to apparent displacement by invasive crayfishes and impairment or change to stream communities and habitat. We recommend increased conservation and management attention to P. connectens and P. gambelii in response to these findings.
AB - Our study evaluates the distribution, habitat associations, and current conservation status of the Snake River pilose crayfish Pacifastacus connectens (Faxon, 1914) and pilose crayfish Pacifastacus gambelii (Girard, 1852), two little-studied and data-deficient species endemic to the western United States. We first developed a species distribution model (SDM) for the pilose crayfishes based on their historical occurrence records using boosted regression trees and freshwater GIS data layers. We then sampled 163 sites in the summers of 2016 and 2017 within the distribution of these crayfishes, including 50 where these species were observed historically. We next compared our field results to modeled predictions of suitable habitat from the SDM. Our SDM predicted 73 sites (45%) we sampled as suitable for the pilose crayfishes, with a moderate AUC value of 0.824. The pilose crayfishes were generally predicted to occur in larger streams and rivers with less extreme upstream temperature and precipitation seasonality. We found the pilose crayfishes at only 20 (12%) of the 163 total sites we sampled, 14 (20%) of the 73 sites predicted as suitable for them by our SDM, and 12 (24%) of 50 historical sites that we sampled. We found the invasive virile crayfish Faxonius virilis (Hagen, 1870) at 22 sites total and 12 (24%) historical sites for the pilose crayfishes, and we found the "native invader" signal crayfish Pacifastacus leniusculus (Dana, 1852) at 29 sites total and 6 (12%) historical sites for the pilose crayfishes. We subsequently used a single classification tree to identify factors associated with our high rate of false positives for contemporary pilose crayfish distributions relative to our SDM. This classification tree identified the presence of invasive crayfishes, impairment of the benthic community, and sampling method as some of the factors differentiating false positives relative to true positives for the pilose crayfishes. Our study identified the historical distribution and habitat associations for P. connectens and P. gambelii using an SDM and contrasted this prediction to results of contemporary field sampling. We found that the pilose crayfishes have seemingly experienced substantial range declines, attributable to apparent displacement by invasive crayfishes and impairment or change to stream communities and habitat. We recommend increased conservation and management attention to P. connectens and P. gambelii in response to these findings.
KW - Boosted regression trees
KW - Ecological niche model
KW - Exotic species
KW - Faxonius virilis
KW - Invasive species
KW - Pacifastacus leniusculus
KW - Signal crayfish
KW - Species distribution modeling
KW - Virile crayfish
UR - http://www.scopus.com/inward/record.url?scp=85054693305&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85054693305&partnerID=8YFLogxK
U2 - 10.7717/peerj.5668
DO - 10.7717/peerj.5668
M3 - Article
C2 - 30280038
AN - SCOPUS:85054693305
VL - 2018
JO - PeerJ
JF - PeerJ
SN - 2167-8359
IS - 9
M1 - e5668
ER -