Effects of two stressors on amphibian larval development

In parallel with a renewed interest in nuclear power and its possible environmental impacts, a new environmental radiation protection system calls for environmental indicators of radiological stress. However, because environmental stressors seldom occur alone, this study investigated the combined effects of an ecological stressor (larval density) and an anthropogenic stressor (ionizing radiation) on amphibians. Scaphiopus holbrookii tadpoles reared at different larval densities were exposed to four low irradiation dose rates (0.13, 2.4, 21, and 222 mGy d−1) from 137Cs during the sensitive period prior to and throughout metamorphosis. Body size at metamorphosis and development rate served as fitness correlates related to population dynamics. Results showed that increased larval density decreased body size but did not affect development rate. Low dose rate radiation had no impact on either endpoint.

► Effects of larval density and ionizing radiation on tadpoles were investigated.
► Increased larval density decreased body size at metamorphosis for the tadpoles.
► Radiation exposure had no impact on either endpoint.
► Results support the IAEA guideline of 10 mGy d−1 for protection of aquatic biota.