Meeting Abstract
Habitat salinization is an emerging concern for freshwater organisms, as rising sea levels, intensified storm surges, road deicing salts and land use changes can all increase salt loading in freshwater systems. Amphibians may be particularly vulnerable to increased salinity due to their semi-aquatic life cycle and permeable skin. Given the complex life cycle typical of amphibians, abilities to cope with environmental challenges may vary among life stages. Although larval amphibians are generally thought to be more sensitive to osmotic challenges than are adults, it is important to understand more about salinity effects throughout the life cycle in order to determine which stages are at greatest risk due to habitat salinization. In this study, we sought to determine salinity tolerance of embryos, tadpoles, newly metamorphosed individuals, and adults of the southern toad, Anaxyrus terrestris. Among these life stages, embryos were the most sensitive to salinity, with almost no survival at 6 parts per thousand. Tadpoles also suffered significant mortality at this salinity. The terrestrial stages, however, were able to withstand solutions of this salinity without dehydrating, though both dehydration and avoidance behavior were seen at higher salinities. Our results suggest that elevated salinity is most likely to affect population dynamics when experienced during embryonic development, and that salinity tolerance appears to increase dramatically during the metamorphic transition. In addition, the tolerance adult toads show for a salinity level that was lethal to embryos suggests that adults must alter salinity avoidance behavior during oviposition.
