Population Ecotoxicology Of The Common Snapping Turtle In Agriculturally Impacted Lotic Ecosystems

Abstract

Anthropogenic impacts on lotic systems, including pollutants, have had both direct and indirect negative effects on the aquatic habitats of the world. Goals of this study are: (1) Quantify atrazine, the atrazine metabolite diaminochlorotriazine (DACT), and glyphosate burdens in common snapping turtle (Chelydra serpentina) tissue from individuals collected within the Embarras River in Coles County, Illinois. (2) Quantify the atrazine, DACT, and glyphosate loads in water from the aquatic habitats in which common snapping turtles reside. (3) Quantify the relative abundance of all turtle species and movement patterns of common snapping turtles in this lotic ecosystem. Hoop nets and modified minnow traps were deployed and all turtles captured were identified to the species level. In addition, common snapping turtles were weighed, sexed, marked, and a tissue sample collected from the tail.

Concentrations of atrazine, DACT, and glyphosate in tissue did not show any relationship with distance from the spillway (Lake Charleston, Illinois), carapace length, width, or mass. Year and gender did show a trend for atrazine in the tissue. Turtles captured the second time tended to have more atrazine and glyphosate in their tissue than when they were first captured; however, a paired t-test did not reveal any significance. Both atrazine and glyphosate tissue samples varied as a function of site, but DACT did not. Tissue concentration of atrazine tended to vary with tissue concentrations of DACT. Beginning at the spillway, atrazine and glyphosate concentrations in water samples showed a linear effect on distance and a deviation from linearity. DACT water samples did not show a linear effect on distance, but there was a deviation from linearity. Water column concentrations of all three contaminants varied across capture sites, but atrazine water concentration did not have an effect on DACT water concentration nor did it exhibit an interaction with site. Water column concentrations of atrazine and glyphosate were greater than tissue concentrations. Water and tissue concentrations of DACT did not differ. Six different species of turtles were found to occur within the river basin. Abundance for both years in descending order was the eastern painted (Chrysemys picta), red-eared slider (Trachemys scripta), eastern spiny soft-shell (Apa/one spin?fera), northern map (Graptemys geographica), and the eastern musk (Sternotherus odoratus). The common snapping turtle was the third most abundant turtle found in the river. Thus, herbivorous turtles were the most abundant and carnivorous turtles were the least abundant. Recapture data revealed that there was no effect of habitat (river vs. slough), year (2008 vs. 2009) or directionality (upstream versus downstream) on mean movement distance of common snapping turtles.

Date of Award	2010
Original language	American English
Awarding Institution	Eastern Illinois University
Supervisor	James Novak (Supervisor)