Examination of environmental DNA (eDNA) is a non-invasive conservation tool that has been used for the detection of aquatic organisms. When coupled with quantitative polymerase chain reaction (qPCR), eDNA sampling may be used to infer seasonal or diel activities of target species. To survey the status of eastern hellbenders (Cryptobranchus a. alleganiensis), fully aquatic cryptic salamanders of conservation concern, through eDNA analyses, we collected water samples monthly from 13 sites across 8 tributaries of the West Branch Susquehanna River in Pennsylvania, USA, from June through October 2014. We also examined the effects of the breeding season, diel activity, and stream environmental variables (e.g., temp, pH) on eDNA concentration estimates. We repeatedly detected hellbender eDNA from all 4 tributaries known to contain hellbenders, and from downstream sites of 2 of the 4 tributaries without known records of hellbenders. In the tributaries known to contain hellbenders, we observed notable increases in eDNA concentrations during the September breeding season, suggesting possible reproductive events. However, such seasonal eDNA signature was lacking from the eDNA positive sites of the tributaries without known records of hellbenders. There was no difference in eDNA estimates between diurnal and nocturnal samples, indicating that diel activity was inconsequential to eDNA estimates. Our statistical analyses of the eDNA positive sites revealed no effects of the stream variables on eDNA estimates. Yet, the presence of hellbenders was positively associated with stream temperature and negatively with pH. The positive association with temperature was likely to be an artifact of the sampling design, whereas the negative association with pH may indicate negative effects of farming and livestock on hellbenders. Our findings concur with recent studies on the importance of temporal sampling in interpreting eDNA signature in relation to life histories of target species. Further studies are needed to characterize the core habitats of newly found populations for future management of the declining hellbender populations. Ó 2017 The Wildlife Society.
Artificial shelters show considerable promise as tools for studying imperiled hellbender salamanders. Their full utility has not yet been fully reached in practice, however, because during initial trials shelters often became blocked by sediment or dislodged during high stream discharge events. To determine whether these challenges could be overcome, we deployed 438 artificial shelters of two different designs across 10 stream reaches and three rivers in the upper Tennessee River Drainage in 2013–2018. We recorded shelter entrance availability during surveys, and recorded which shelters became dislodged following high discharge events. We evaluated two hypotheses: (a) shelter availability was driven by shelter placement and maintenance frequency and (b) shelter stability was driven by shelter design and shelter placement. Shelters were available 78.6% of the time on average (range = 0–100%), and 88.6% (388 of 438) of shelters were stable across all high discharge events. Shelter availability was maximized by clearing sediment from shelter entrances at least once every 40 days (more often in impaired reaches with high siltation) and after large storm events, situating the shelter within 1 m of ≥5 boulders, and orienting shelters such that their entrances do not face directly downstream. Shelter stability with our initial shelter design was 77.5% (169 of 218), but approached 100% (219 of 220) for heavier (~40 kg vs. ~25 kg) shelters with recessed lids, and in reaches with abundant large boulders. Our findings demonstrate that with an improved design and careful placement, artificial shelters can serve as valuable tools for monitoring hellbenders in reaches with modest siltation.
Spawning behaviour of the chestnut lamprey, Ichthyomyzon castaneus, was observed June 11 and 12, 1968, in coarse gravel near the tailrace of a dam in the Rat River, Manitoba, a tributary of the Red River. No description of spawning behaviour of this species has been previously published.
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