Atrazine Exposure Impacts Behavior and Survivorship of Neonatal Turtles

Atrazine (2-chloro-4-ethythlamino-6-isopropylamine-1,3,5-tiazine) is a widely used preemergent herbicide for controlling broadleaf plants. Because atrazine (a known endocrine-disrupting chemical) is applied in the late spring and early summer, its incidental effects on species exposed to runoff from terrestrial sources in this time period are of special interest. To examine the possible secondary impact of atrazine, we obtained eggs from 10 nests of two map turtle species, Graptemys ouachitensis and G. pseudogeographica, that nest on riverine sandbars. We incubated two eggs from each nest in sand containing one of four initial concentrations of atrazine (control and 0.1, 10, and 100 mg/L) based on levels measured in the river at the site where eggs were collected. We recorded hatching success, incubation time, external morphological abnormalities, gonadal sex, three measures of body size, righting time, and swimming time for all turtles. We reared a subset of the original neonates individually for 11 mo, during which time nest escape behavior, time to first foraging event, time to capture prey, growth, and survival were evaluated. None of the variables recorded at hatching was significantly affected by atrazine treatment, although abnormalities declined as atrazine levels increased. However, turtles deriving from the lowest atrazine-treated eggs had inhibited nest escape behavior and reduced posthatching survival. These findings reveal persistent fitness-reducing impacts on neonatal turtles resulting from atrazine exposure during embryonic development.