Interactive effects of a heavy metal and chytridiomycosis on Gray Treefrog larvae (Hyla chrysoscelis)

Abstract

We studied the effects of a pathogenic fungus (Batrachochytrium dendrobatidis, Chytridiomycota) on larval fitness in the Gray Treefrog (Hyla chrysoscelis). Recent studies have identified chytrichomycosis as an emerging infections disease that poses a significant risk for amphibian populations worldwide. We also tested the effects of the heavy metal copper, a common environmental contaminant in aquatic environments, on larval fitness. We reared larvae in laboratory containers and tested whether exposure to copper and B. dendrobatidis affected Hyla survival, growth, and development. Neither exposure to B. dendrobatidis nor copper significantly affected survival to metamorphosis. Metamorphic body mass was significantly reduced in the presence of B. dendrobatidis, but copper did not significantly affect larval growth. Both copper and B. dendrobatidis exposure significantly increased larval period length, but copper differentially affected development in the presence of B. dendrobatidis. Hyla developed more slowly when reared in the presence of B. dendrobatidis in copper-free conditions or at a low copper concentration. This significant copper-by disease interaction suggests that, for some traits, the impact of chytridiomycosis on larval amphibians may be affected by the presence of copper.