PARENT SESSION
PT1 - Aquatic Toxicology
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P528) Effects of Sublethal Exposure to Atrazine on Amphibian Activity and Response to Alarm Cues.

Brown Sullivan, Karen^*,1, ¹ Wichita State University, Wichita, KS, USA

ABSTRACT- Tadpoles of the Woodhouse toad (Bufo woodhousei) that had reached feeding stage were exposed for two weeks to 0,40, or 320 g/L of the herbicide atrazine in static renewal tests. These concentrations of atrazine are not uncommon in temporary pools near agricultural fields during spring application, a time when many amphibians are breeding. After the two week exposure, 25 tadpoles were randomly selected from each treatment for behavioral tests. Individuals were videotaped singly in a plastic container visually divided into halves. A 10 min acclimation was followed with a 5 min observation termed the "pre-alarm" period. After this, 5 ml of homogenated tissue of conspecific tadpoles (i.e., the alarm cue) was added to the half of the container opposite the tadpole's position and a 5 min "post-alarm" observation was conducted. Within each treatment group of tadpoles, activity decreased significantly after addition of the alarm cue. Tadpoles in the 0 and 40 g/L groupls, but not the 320 g/L group, significantly decreased the number of lines crossed after cue addition. Although all three groups exhibited a decrease in activity following the cue, suggesting a similiar predator avoidance response, there were differences among tadpole groups in activity prior to the alarm cue addition. Tadpoles reared at 320 g/L atrazine were signifcantly less active and crossed fewer lines in the pre-alarm cue period. Also, tadpoles in the 320 g/L group exhibited signifcantly less of a proporational decrease in activity following alarm cue addition. The decreased activity noted among tadpoles exposed to the higher atrazine concentration has negative implications for tadpole survivorship in the wild. Decreased activity may lower foraging efficiency, delaying growth and causing smaller size at metamorphosis.

Key words: Atrazine, Amphibian activity, Predator responses