Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

2010

Thesis Director

Stephen Mullin

Thesis Committee Member

Karen Gaines

Thesis Committee Member

Kip McGilliard

Abstract

Ecotoxicological studies that focus on a single endpoint might not accurately represent the true ecological effects of a contaminant. Exposure to atrazine, a widelyused herbicide, disrupts endocrine function and sexual development in amphibians, but studies involving reptilian species are lacking. This study examines several effects of atrazine ingestion on gravid females and neonates exposed in utero of the Northern Watersnake (Nerodia sipedon). Twenty-five gravid N. sipedon were collected and kept in the lab for the entirety of their gestation period. Each snake received one of four doses of atrazine: control, 2, 20, or 200 ppb. Blood samples were drawn each week to quantify the estradiol levels, and female survival was monitored throughout the study. Following birth, the neonate morphometrics, sex ratio, and percent stillborn were recorded. Data analyses showed that atrazine ingestion potentially disrupts estradiol production in females, inhibits the immune response, alters sex ratio, and causes a higher proportion of stillborn neonates. Findings such as these emphasize the need for additional research involving other reptile species and multiple endpoints in order to determine the full range of ecological impacts that are manifested by contaminant exposure.

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