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Hydroperiod variability constrains populations of amphibians dependent on ephemeral wetlands
Citation:
Awkerman, J. AND C. Greenberg. Hydroperiod variability constrains populations of amphibians dependent on ephemeral wetlands. 2022 Annual Meeting of the Ecological Society, Montreal, Quebec, CANADA, August 14 - 19, 2022.
Impact/Purpose:
Existing risk assessment practices that focus on standard toxicological data fail to contextualize extrinsic stressors. Amphibian populations are affected by multiple stressors, not least of which is habitat availability in changing ecosystems. This study evaluates the effects of variable breeding habitat availability as well as pesticide exposure during the larval stage to provide perspective on population-level impacts on anuran amphibians dependent on ephemeral wetlands.
Description:
Amphibian populations are threatened by multiple potential stressors, including environmental variability and climate-related changes in habitat availability. A contributing factor in changing ecosystems is the availability of breeding habitat for anuran amphibians that are dependent on ephemeral wetlands. Determining the population-level impacts of contaminant exposure and pathogens is further complicated in species with biphasic life cycle and both aquatic and terrestrial resource needs. Ecological risk assessment of amphibians ideally should encompass the appropriate spatial and temporal scale to adequately capture influential ecological processes and demographic responses. To demonstrate the importance of representing environmental stochasticity in population assessments, climate change models identifying suitable breeding habitat were used to project population dynamics for southern toad (Anaxyrus terrestris) populations, including possible scenarios of impacted breeding habitat. These impacts include both probabilistic and projected estimation of complete reproductive failure in years with unsuitable breeding habitat as well as reduced larval survival resulting from pesticide exposure. Populations were most impacted by long periods of inadequate breeding habitat. The impact of multiple sequential years of reproductive failure emphasizes the necessity of reliable climate projections to accurately represent the effects of reduced breeding habitat availability on amphibian populations. Flexible modifications to existing risk assessment methods, allowing inclusion of various extrinsic stressors and identifying demographic and ecological vulnerabilities could greatly improve existing approaches.
