Effects of the herbicide atrazine on Ambystoma tigrinum metamorphosis: duration, larval growth, and hormonal response

Larson, D. L.; McDonald, S.; Fivizanni, A. J.; Newton, W. E.; Hamilton, S. J.

Abstract:

We exposed larval tiger salamanders (Ambystoma tigrinum) reared in the laboratory from eggs collected from a prairie wetland in North Dakota to three concentrations of atrazine (0, 75, and 250 i??g/L) in a static renewal test to determine the pesticide‘s effect on (1) plasma corticosterone and thyroxine concentrations, (2) larval size, and (3) days-to-stage at stages 2 and 4 of metamorphic climax. We found significant effects of atrazine on each of these response variables. Plasma thyroxine was elevated in both atrazine-exposed groups compared to the control group; plasma corticosterone was depressed in the 75 i??g/L treatment compared with both the control and 250 i??g/L treatment. Larvae exposed to 75 i??g/L atrazine reached stage 4 later, but at a size and weight comparable to the control group. By contrast, larvae in the 250 i??g/L treatment progressed to stage 4 at the same time but at a smaller size and lower weight than larvae in the control group. These results indicate that the herbicide has the potential to influence tiger salamander life history. We present a model consistent with our results, whereby corticosterone and thyroxine interact to regulate metamorphosis of tiger salamanders based on nutrient assimilation and adult fitness

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Article

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1001102

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Larson, D. L.; McDonald, S.; Fivizanni, A. J.; Newton, W. E.; Hamilton, S. J.

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Northern Prairie Wildlife Research Center

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679

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English

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Physiological Zoology

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p. 671-679

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Effects of the herbicide atrazine on Ambystoma tigrinum metamorphosis: duration, larval growth, and hormonal response; 1998; Article; Journal; Physiological Zoology; Larson, D. L.; McDonald, S.; Fivizanni, A. J.; Newton, W. E.; Hamilton, S. J.