Decline of a giant salamander assessed with historical records, environmental DNA and multi‐scale habitat data. (28th March 2017)

• Record Type: Journal Article
• Authors: Pitt, Amber L.; Shinskie, Jamie L.; Tavano, Joseph J.; Hartzell, Sean M.; Delahunty, Tina; Spear, Stephen F.
• Is Part Of: Freshwater biology. Volume 62:Number 6(2017)
• Page Start: 967
• Page End: 976
• Publication Date: 2017-03-28
• Subjects: conductivity -- environmental DNA (eDNA) -- hellbender salamander -- population decline -- watershed deforestation; Freshwater biology -- Periodicals; Biologie d'eau douce -- Périodiques; 577.605
• DOI: 10.1111/fwb.12917
• Languages: English
• ISSNs: 0046-5070

Abstract

Abstract: Freshwater species are declining rapidly but more complete data are needed for determining the extent and cause(s) of population declines and extirpations. Integrating newer survey techniques, freely available data, and traditional field work may allow for more effective assessment of population decline. We used detailed historical species records and environmental DNA (eDNA) survey methods to identify changes in population distribution of a long‐lived, imperiled stream salamander, the eastern hellbender ( Cryptobranchus alleganiensis alleganiensis : Cryptobranchidae). We used logistic regression with Bayesian inference to test whether selected environmental variables may be good predictors of hellbender population persistence and extirpation. Hellbenders persisted in only 42% of the 24 historical record sites. The best fit model indicated electrical conductivity (EC) was the strongest predictor of hellbender population persistence (EC < 278 μS/cm) and extirpation. Conductivity was strongly negatively correlated with canopy cover within the total watershed ( r = −0.83, n = 21, p < 0.001) and riparian buffer of the watershed ( r = −0.77, n = 21, p < 0.001). Electrical conductivity tends to increase following deforestation, and may inhibit sperm motility and thus limit recruitment of hellbenders and other aquatic vertebrate species with external fertilisation. By integrating historical data, eDNA, field data, and freely available high resolution remote sensing data, our study design allowed for rapid assessment of predictors of and changes in hellbender distribution over a relatively broad geographic area. This cost‐ and time‐effective approach may be used for evaluating other rare aquatic species.