Limited impacts of acid runoff from pyrite-bearing rock formations on stream salamanders in Middle Tennessee headwater streams
Nicole A. Witzel, De’Etra Young, Thomas D. Byl, Brittaney Hogan, and William B. Sutton
In addition to the myriad anthropogenic disturbances that impact biota and conservation efforts, acidification of aquatic habitats is an important threat to aquatic biodiversity. In this study, we examined the effects of acid rock drainage (ARD) on stream salamander assemblages in streams associated with rock cuts and pyrite-bearing Chattanooga and Fentress Shale formations in Middle Tennessee. We selected two streams monitored by the United States Geological Survey for changes in water quality and used a paired study design to evaluate the impacts of ARD by monitoring sites above and below the ARD disturbance. We surveyed a single transect and two quadrats (each surveyed once) in each paired stream reach at both sites and captured 158 larval and adult stream salamanders of 6 species. Salamander counts were similar for adult and larval salamanders between ARD-impacted and unimpacted stream reaches. Biodiversity measures (species richness, diversity, and evenness) did not differ between ARD-impacted and unimpacted stream reaches. Similarly, adult and larval counts for the Spotted Dusky Salamander (Desmognathus conanti) and Southern Two-lined Salamander (Eurycea cirrigera) did not differ between reaches. In terms of species composition, adult and larval E. cirrigera captures represented 37.9% and 94.2% of captures in ARD-impacted reaches versus 6.7% and 84.2% of captures in unimpacted reaches. We did not detect significant differences in water quality measurements (pH, temperature, and dissolved oxygen) between ARD-impacted and unimpacted stream reaches. We attribute the lack of stream disturbance effects to mitigation measures (limestone rock abatements) that were implemented above ARD-impacted stream reaches after road cut disturbance. Collectively, our pilot study provides an initial examination of the impacts of ARD on stream salamander assemblages in Tennessee, and suggests that impacts at these two sites are limited. However, a broader scale and replicated field study is necessary before larger conclusions can be established.
Key Words.—acid rock drainage; Desmognathus; disturbance; Eurycea; lotic; Plethodontidae; riparian
Key words. — Amphibian, Bacteroidetes, direct colony PCR, probiotics, Proteobacteria, streamside salamander