Monitoring Selenium Levels in Painted Turtles (Chrysemys picta) in South Dakota Wetlands

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Tile drain systems have been one of the most important advancements in agriculture. Tile drains are subsurface drainage systems that move water from crop fields to streams, ditches, and wetlands. Selenium is a necessary mineral but is considered toxic at high levels. Wetlands with tile drains are at a higher risk for elevated selenium concentrations. Selenium enters the aquatic ecosystem in the benthic food web that is then consumed by invertebrates, and it continues to bioaccumulate mainly via direct transfer in higher trophic level taxa such as fish, amphibians, reptiles, birds, and mammals. For this study, painted turtles (Chrysemys picta) served as our model organism to detect selenium levels in higher trophic level organisms. We hypothesize that tile site turtles' blood level Selenium concentration will be higher compared to the control site turtles. During the summer of 2019, we collected soil, water and turtle blood samples from four control (a relatively pristine wetland with no direct input of contaminants) and four tile wetland (a wetland with a direct input of contaminants from a tile drain) sites. Fifteen control and nineteen tile site turtle blood samples were collected (n=34). The EPA Selenium criteria is 11.3 mg/kg for fish and 1.5ug/L for lentic water. Selenium concentrations above 11.3 mg/kg or above physiological function has shown to be genotoxic and carcinogenic. The entire health of the aquatic ecosystem is at risk if key, top predators, such as turtles, are eliminated from the food web due to Selenium toxicity.

First Advisor

Jacob Kerby

Second Advisor

Anna Kase

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