The Effect of Chytridiomycosis and Bioaugmentation on the Metabolic Rate of Redbacked Salamanders, Plethodon cinereus

Abstract

The infectious disease chytridiomycosis caused by the fungal pathogen Batrachocytrium dendrobatidis, Bd, contributes to worldwide amphibian decline, but definitive pathogenesis of lethality for the disease is not well understood. Because amphibians respire through their skin (in addition to respiration using lungs), it is speculated that amphibians with chytridiomycosis may show a decrease in metabolic rate, but amphibians bioaugmented with probiotic bacteria may alleviate possible metabolic stress. A species of lungless salamander (Plethodon cinereus) was used in this study to analyze the cutaneous effects of Bd on metabolic rate in vivo. Net weight change, infection load (using a Taqman real time PCR assay), and metabolic data (using an FMS) of salamanders were recorded over the course of a 25 day span. Data demonstrate that salamanders infected with Bd may possess a higher overall metabolic rate, but further research must be conducted to confirm statistical significance. Real time Taqman PCR results suggest that salamanders infected with Bd were able to clear infections in less than two weeks due to rise and subsequent decline in detection of zoospore genomic equivalence despite showing weight loss and other characteristic symptoms of chytridiomycosis. Further research including more intense infection of salamanders, application of techniques to minimize PCR inhibitors, and recording of metabolic data in a refined experimental environment are needed to better understand these phenomena.