Failure of tetracycline as a biomarker in batch-marking juvenile frogs

Recent widespread amphibian declines call for better techniques to assess p opulation dynamics. Tetracycline as a biomarker in capture-recapture studie s is one technique used successfully in fish, reptiles, and mammals. A two- phase experimental study was conducted to evaluate tetracycline as a biomar ker in green frogs (Rana clamitans) and pickerel frogs (Rana palustris). In the first experimental phase tadpoles were exposed to water containing eit her 250 mg/l or 500 mg/l tetracycline for a period of 24 hr. During the sec ond phase, juvenile frogs were exposed to tetracycline in water at 500 mg/l or given injections of tetracycline at the dose rate of 100 mg/kg body wei ght. At selected times several weeks later, under tricaine methanesulfonate anesthesia, a toe was surgically excised from each animal, sectioned and v iewed under an ultraviolet microscope. No significant differences were foun d between tile various treatments and control animals (untreated). Therefor e, the use of tetracycline as a biomarker in anurans using these techniques is not recommended.