Carryover effects of wastewater treatment reduce anuran success

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Zeitler, Emma
Cecala, Kristen
McGrath, Deborah
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Wastewater treatment , Scholarship Sewanee 2020 , Anuran , Amphibian ecology , Constructed wetlands , Contaminants , Pharmaceuticals , Wastewater management
Constructed wetlands are a potential solution for wetland mitigation and wastewater treatment due to their ability to simultaneously support native species and provide tertiary wastewater treatment. However, they can expose wildlife communities to excess nutrients and harmful contaminants, affecting their development, morphology, and behavior. To examine how the ecology of constructed wetlands may affect wildlife, we raised Southern Leopard Frogs (Lithobates sphenocephalus) in wastewater from traditional treatment and constructed wetland treatment and untreated drinking water and monitored their juvenile development for any carryover effects in the terrestrial environment. Individuals emerging from the secondarily treated wastewater demonstrated higher survival rates and faster time to metamorphosis but had lower survival as terrestrial juveniles than those emerging from untreated drinking water. Individuals from wastewater treatments exhibited differential growth for specific morphological features with faster growth in the aquatic environment and then slower growth in the terrestrial environment relative to those from untreated drinking water. Common duckweed (Leman minor) had smaller but generally positive effects on aquatic development and no impact on terrestrial development. Finally, we found that 2.64% of individuals from wastewater environments had visible external abnormalities. Our results reflect a trade-off between short-term developmental benefits of development in treated effluent and long-term consequences on overall fitness. Overall, we demonstrate that constructed wetlands for the purpose of wastewater treatment are not suitable replicates for wildlife habitat and may have consequences for local population dynamics.