Temperature causes species-specific responses to UV-induced DNA damage in amphibian larvae

Abstract

Anthropogenic ozone depletion has led to a 2-5% increase in ultraviolet B radiation (UVBR) levels reaching the earths surface. Exposure to UVBR causes harmful DNA damage in amphibians, but this is minimized by DNA repair enzymes such as thermally sensitive CPD-photolyase, with cool temperatures slowing repair rates. It is unknown whether amphibian species differ in the repair response to a given dose of UVBR across temperatures. We reared larvae of three species (Limnodynastes peronii, Limnodynastes tasmaniensis, and Platyplectrum ornatum) at 25{degrees}C and acutely exposed them to 80 W cm-2 UVBR for 2 h at either 20{degrees}C or 30{degrees}C. UVBR-mediated DNA damage was measured as larvae repaired damage in photoreactive light at their exposure temperatures. Cool temperatures increased DNA damage in all two species and slowed DNA repair rate in P. ornatum. The magnitude of DNA damage incurred from UVBR was species-specific. P. ornatum had the lowest CPDs and DNA repair rates, and the depressive effects of low temperature on photorepair were greater in L. tasmaniensis. Considering the susceptibility of most aquatic organisms to UVBR, this research highlighted a need to consider the complexity of species-specific physiology when forecasting the influence of changing UVBR and temperature in aquatic ecosystems.