Meeting Abstract
Salinization of freshwater ecosystems is an emerging environmental concern, as rising sea levels, intensified storm surge, road deicing salts, and land use changes can contribute to increased salinity in freshwater habitats. Elevated salinity can increase the demands of osmoregulation in freshwater organisms, and amphibians are particularly at risk due to their semi-aquatic life cycle and permeable skin. Tolerance to environmental challenges may vary during development, with individual- and population-level impacts dependent on the timing of exposure relative to the timing of vulnerability. In addition, among larval amphibians, the life history consequences of various stressors can vary with the timing of exposure to stress. We manipulated timing and duration of exposure to elevated salinity during larval development of southern toad (Anaxyrus terrestris) tadpoles, across three experiments, and examined effects on survival, larval growth, and timing of and size at metamorphosis. Tadpoles exposed to elevated salinity early in development were the least tolerant, suggesting an increase in tolerance during larval development. Life history effects also depended on the timing of exposure, suggesting a potential constraint related to a loss of developmental plasticity leading up to the metamorphic transition. Our results suggest that elevated salinity is most likely to affect population dynamics when experienced early during larval development. Further, through life history effects, even sublethal salinity exposure in the larval environment may influence success in subsequent life stages.
