Anakeesta Stream Acidification and Metal Contamination: Effects on a Salamander Community

Abstract

AbstractWe examined how stream degradation can affect adjoining streamside communities by comparing the density, age structure, and microhabitats of salamanders in forests adjoining contaminated and noncontaminated sections of Beech Flats Creek in the Great Smoky Mountains National Park. A section of Beech Flats Creek was contaminated due to exposure of Anakeesta rock formations in 1963. Chronic changes that have occurred since then include a reduction in pH, an increase in metal concentrations, and a nearly complete elimination of all macroinvertebrates, salamander larvae, and fish. Comparisons of control and impacted plots indicate that two stream‐breeding species (Desmognathus quadramaculatus; Eurycea wilderae) have been nearly eliminated from impacted stream sections, while two other species (D. ochrophaeus; D. imitator) that breed in both streams and seepages have been reduced by about half. In contrast, terrestrial‐breeding species (Plethodon jordani; D. wrighti) appear to have increased markedly following the reduction in stream‐breeders. Juvenile P. jordani comprised a significantly greater percentage of the population on impacted plots compared with controls. Microhabitat use on control and impacted plots did not differ significantly for any species. Changes in the densities and age structure of terrestrial breeders on impacted plots may have been due to the elimination of D. quadramaculatus, which is a major predator on other salamanders, or to release from competition with adults of stream‐breeding species. Overall, our data indicate that stream contamination from Anakeesta exposure can alter the structure of streamside salamander communities both by directly eliminating species with biphasic life cycles, and by indirectly altering ecological interactions among community members.