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PH04 Ecotoxicology of Atrazine in Amphibians
(PH058) Effects of Atrazine on Fluctuating Asymmetry of Xenopus laevis Tadpoles.
Gurung, N.1, Brown Sullivan, K., 1 Department of Biological Sciences, Wichita State University, Wichita, KS, USA
ABSTRACT- Fluctuating asymmetry (FA), differences between right and left side bilateral traits of an individual, has been proposed for use both as an indicator of prior environmental stress and potential organismal fitness. Comparatively high FA is hypothesized to be associated with historical stressors and decreased quality. These suppositions are largely based on correlational data taken on field-collected organisms for which little historical or habitat information is known. This study was conducted to determine the relationship between individual FA and traits related to metamorphosis among tadpoles of Xenopus laevis exposed during the larval period to environmentally realistic concentrations of atrazine (0, 40 and 320 g/L). Tadpoles from two groups of full-siblings were exposed to atrazine concentrations via 3-day static renewal tests. Age, body weight and snout-vent length at metamorphosis were recorded. Those tadpoles exposed to greater atrazine concentrations exhibited significantly delayed metamorphosis and decreased body sizes compared to control animals. At metamorphosis, tadpoles were preserved in 70% ethanol. For FA analysis, approximately 75 animals from each atrazine treatement were stored in 1% KOH to clear tissues, followed by staining of bones with alizarin red dye. Cleaned bones for each individual were covered in glycerol for preservation. A camera attached to a stereomicroscope was used to photograph skeletal traits. Photographs were transferred to computer and measurements were made on 31 bilateral skeletal traits using Adobe Photoshop for PC. FA measures for both individual traits and composite FA indices (e.g., average FA among traits) were determined. Preliminary analyses based on only a portion of the data set indicated no significant differences in FA among tadpoles exposed to atrazine. Results for the full data set will be presented to determine if FA is related to atrazine exposure and life-history traits at metamorphosis.
Key words: Fluctuating Asymmetry, Xenopus laevis, Atrazine
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