Long-term, landscape-level assessment of aquatic pesticide exposure to identify amphibian ontological traits affecting vulnerability
Citation:
Awkerman, J., Tom Purucker, Sandy Raimondo, AND L. Oliver. Long-term, landscape-level assessment of aquatic pesticide exposure to identify amphibian ontological traits affecting vulnerability. Integrated Environmental Assessment and Management. Allen Press, Inc., Lawrence, KS, 20(5):1667-1676, (2024). https://doi.org/10.1002/ieam.4924
Impact/Purpose:
o Amphibians are particularly challenging species for ecological risk assessment but also some of the most threatened populations globally, due to a number of potential threats, including pesticide impacts. Precise evaluation of pesticide effects are difficult due to variable demography, field data deficits, and the frequent use of surrogate species from different taxonomic groups for risk assessment of separate amphibian life stages. Here we simulate realistic pesticide application scenarios in representative habitat to determine the potential impacts of both exposure and environmental stochasticity on interannual recruitment in eight species of amphibians over a 61-year period. Incorporation of the Pesticide in Water Calculator in these simulations offers a screening-level approach for ecological risk assessment of amphibians that includes environmentally realistic scenarios.
Description:
Amphibians worldwide are threatened by habitat loss, some of which is driven by a changing climate, as well as exposure to pesticides, among other causes. The timing and duration of the larval development phase vary between species, thereby influencing the relative impacts of stochastic hydroregime conditions as well as potential aquatic pesticide exposure. We describe the stages of breeding through metamorphosis for eight amphibian species, based on optimal hydroregime conditions, and use a model of pesticide fate and exposure representative of central Florida citrus groves to simulate hydrodynamics based on observed weather data over a 54-year period. Using the Pesticide in Water Calculator and Plant Assessment Tool, we estimated daily wetland depth and pyraclostrobin exposure, with label-recommended application quantities. Species' timing and duration of larval development determined the number of years of suitable hydroregime for breeding and the likelihood of exposure to peak aquatic concentrations of pyraclostrobin. Although the timing of pesticide application determined the number of surviving larvae, density-dependent constraints of wetland hydroregime also affected larval survival across species and seasons. Further defining categorical amphibian life history types and habitat requirements supports the development of screening-level assessments by incorporating environmental stochasticity at the appropriate temporal resolution. Subsequent refinement of these screening-level risk assessment strategies to include spatially explicit landscape data along with terrestrial exposure estimates would offer additional insights into species vulnerability to pesticide exposure throughout the life cycle. Computational simulation of ecologically relevant exposure scenarios, such as these, offers a more realistic interpretation of differential agrichemical risk among species based on their phenology and habits and provides a more situation-specific risk assessment perspective for threatened species.
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DOI: Long-term, landscape-level assessment of aquatic pesticide exposure to identify amphibian ontological traits affecting vulnerability