EDI Staging Environment
Aquatic systems worldwide are threatened by the anthropogenic use of synthetic chemicals, including pesticides,
pharmaceuticals, and road de‐icers. Exposure to contaminants can alter the behavior, morphology, and physiology of
organisms if it occurs during sensitive life stages. For instance, past studies have documented feminization of male amphibians
following herbicide exposure and skewed sex ratios among amphibian populations exposed to road salt. However,
many of these studies lack the complexities found within natural environments, such as competition with conspecifics or
threat of predation, which are also known to influence development. Thus, it is important to understand how anthropogenic
and natural stressors interact to alter animal sex ratios. Given the growing concern of secondary salinization of freshwater
systems, we exposed larval wood frogs (Rana sylvatica) to either road salt (sodium chloride [NaCl]) or an alternative salt
mixture (NaCl, magnesium chloride [MgCl2], and potassium chloride [KCl]) at 3 concentrations (200, 600, and 1000 mg Cl−/L)
crossed with 3 biotic stressors (no‐stressor control, competition, or predator cues) to examine their potentially interactive
effects on sex. Exposure to biotic stressors and NaCl did not influence wood frog sex ratios. In contrast, tadpole exposure to
the intermediate salt mixture concentration significantly reduced the proportion of female frogs. Future studies are needed
to determine whether such changes in sex are widespread among sensitive species with complex life cycles, and to assess
the consequences of sex ratio changes on long‐term population dynamics.
EDI is a collaboration between the University of New Mexico and the University of Wisconsin – Madison, Center for Limnology:
