Bioaccumulation and Trophic Transfer of Selenium in South Dakota Tile Wetland Species

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Agricultural activities, specifically tile drainage systems, have accelerated the rate at which elemental compounds are released from the earth. Selenium (Se), a naturally occurring essential element, plays a critical role in many biological processes, yet has a narrow range between essentiality and toxicity. Se is often retained in the sediment of shallow wetlands; such as tile wetlands, where it can be readily accumulated by benthic invertebrates and enter the food chain through dietary transfer. This study focused on collecting samples at the same time and location to more clearly link the pathway of Se in tile wetland food chains and determine if Se accumulation differs between two amphibian predators. Se concentrations were measured in sediment, surface water, benthic invertebrates, terrestrial emergent invertebrates, and larval western tiger salamander (Ambystoma mavortium) and adult American toad (Anaxyrus americanus) liver samples collected from control and tile wetlands. Preliminary results indicate higher selenium concentrations in surface water and sediment samples collected from tile wetlands compared to control sites. Elevated selenium levels were also detected in vertebrate liver samples collected from tile sites compared to control wetlands, raising concerns about the impacts of modern farming practices on native species at protected wetlands.

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Jacob Kerby

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