Modelling occupancy of an imperilled stream fish at multiple scales while accounting for imperfect detection: implications for conservation

Abstract

Summary Predictive models of species distribution are useful tools to identify habitats of imperilled species for protection, inventory and restoration. Critical aspects of such models include the influence of scale, uncertainties associated with imperfect detection and spatial autocorrelation and transferability of model predictions. We addressed these issues in developing occupancy models of the imperilled eastern sand darter (Ammocrypta pellucida) based on surveys of the Grand and Thames Rivers, Ontario, Canada. Eastern sand darter detection probabilities were remarkably different between streams, but factors affecting site occupancy were similar. The proportion of sand and fine gravel was most important, but water clarity and biotic indices also received support in additive models. Accounting for spatial autocorrelation reduced the effect of important covariates. Occupancy was more closely related to substratum at the site level than factors at broader scales (reach and valley segment), further emphasising the substratum specificity of this species. Almost all of the top‐ranked site and reach occupancy models had good predictive performance based on assessments of transferability. These models indicate that three formerly occupied Ontario catchments have a high probability of supporting the species and deserve consideration for repatriation. Our methods demonstrate how a comprehensive approach to occupancy modelling can be used to help guide recovery efforts for imperilled species.

Accuracy and efficiency of detection dogs: a powerful new tool for koala conservation and management

“…Species distribution models notoriously perform badly with imperfect detection26. Occupancy models that account for imperfect detection are therefore gaining popularity (see for instance27) but they are not always better at predicting species distribution28. This is why decreasing false negatives created by imperfect detection remains the most effective way of getting accurate distributions.…”

Importance of antecedent environmental conditions in modeling species distributions

“…To account for potential spatial structuring in species occurrence patterns (Dormann , Dextrase et al , Huang and Frimpong ), we applied a distance‐based Moran's Eigenvector maps approach (Borcard and Legendre , Dray et al , Blanchet et al , Legendre and Gauthier ). This approach is conceptually similar to Fourier analysis, which explains the variability of an observed pattern via a combination of trigonometric‐curves with multiple scales (e.g.…”

Effect of substrate size on sympatric sand darter benthic habitat preferences

“…Sand darters are habitat specialists and thus sensitive to habitat alterations, which is why both species are often valued as indicators of ecosystem integrity (Grandmaison et al 2004;Drake et al 2008). Habitat use and sand grain size preference is well documented for the eastern sand darter (Daniels 1993;Facey & O'Brien 2004;Drake et al 2008;O'Brien & Facey 2008;Tessler et al 2012;Dextrase et al 2014), but literature pertaining to the western sand darter is sparse, and little information is available from areas where the two species are sympatric.…”

“…Laboratory studies that investigated eastern sand darter substrate use reported that individuals generally used medium (0.25-0.5 mm) sized particles (Daniels 1993;O'Brien & Facey 2008). Furthermore, field surveys revealed that the species was commonly detected in sand comprised of fine to medium (0.12-0.5 mm) particles, while few individuals were detected in areas where the particle size was larger than 1.0 mm (Facey & O'Brien 2004;Tessler et al 2012;Dextrase et al 2014). Pflieger (1971) noted that in Missouri the western sand darter avoided strong currents, inhabiting shallow backwater areas, as well as quiet margins of a drainage canal at depths up to 1.5 m. Simon et al (1992) observed the western sand darter spawning and described the habitat as an area on the downstream side of an island with a slow current over coarse sand.…”