Landscape- and local-scale habitat influences on occupancy and detection probability of stream-dwelling crayfish: implications for conservation

Environmental DNA detects a rare large river crayfish but with little relation to local abundance

“…6th order) freshwater rivers, although the ability of this approach to accurately reflect species presence or abundance in flowing waters might be hindered by the downstream transport of detectable eDNA in some cases. We found a poor relationship between F. eupunctus eDNA detection probability and local F. eupunctus density, despite using a rigorous and well‐studied conventional sampling method to estimate F. eupunctus densities (Engelbert et al., ; Magoulick et al., ; Nolen et al., ). Alternatively, we found a strong relationship between eDNA detection probability and upstream river distance, which we used as a proxy for the risk of downstream transport of eDNA from upstream F. eupunctus populations.…”

“…Despite these encouraging results, it remains to be seen whether eDNA can reflect presence and abundance of narrowly endemic crayfishes in larger, perennial streams where eDNA transport is more likely to be a problem (Deiner & Altermatt, ). Further, it is unknown how well eDNA applications in such systems will agree with data collected through conventional sampling methods that are well‐suited for crayfishes inhabiting wadeable streams (Engelbert, Taylor, & DiStefano, ; Magoulick et al., ; Nolen, Magoulick, DiStefano, Imhoff, & Wagner, ).…”

“…Previous data suggest F. eupunctus inhabits a limited portion of the main stem Eleven Point River and the downstream reaches of a few of its direct tributaries (Fetzner et al., ; Pflieger, ). Research to date has found F. eupunctus primarily associated with higher order streams, greater groundwater spring flow volumes and higher current velocity, thus making F. eupunctus a large river habitat specialist relative to sympatric congeneric crayfishes (Flinders & Magoulick, ; Magoulick et al., ; Nolen et al., ). Faxonius eupunctus is recognised as Threatened by the American Fisheries Society (Taylor et al., ) and Vulnerable by the International Union for Conservation of Nature (Richman et al., ), and it is currently being evaluated for federal protection under the United States Endangered Species Act (ESA), owed in part to its narrowly endemic range and risk for displacement by non‐native crayfishes (DiStefano, Imhoff, Swedberg, & Boersig, ; Imhoff, Moore, & DiStefano, ).…”

“…In this study, we developed a quantitative PCR (qPCR) assay for species‐specific detection of F. eupunctus eDNA. We compared the capacity of eDNA to infer F. eupunctus presence and abundance to that of a conventional sampling method commonly used to survey crayfishes in wadeable streams of Arkansas and Missouri (Engelbert et al., ; Magoulick et al., ). Further, we estimated F. eupunctus eDNA detection probabilities and examined relationships between eDNA detection probability and site‐scale variables using a hierarchical occupancy and detection probability modelling framework (Schmidt, Kéry, Ursenbacher, Hyman, & Collins, ; Smart, Tingley, Weeks, Van Rooyen, & McCarthy, ).…”

Quantifying Seining Detection Probability for Fishes of Great Plains Sand‐Bed Rivers

“…Imperfect detection is an issue that applies to most, if not all, species (Kéry and Schmidt ) and has been documented for less mobile organisms such as crayfishes (Magoulick et al. ) and even plants (Kéry et al. ; Garrard et al.…”