GOLEMAN, W.L.*; CARR, J.A.; URQUIDI, L.J.; ANDERSON, T.A.; THEODORAKIS, C; SMITH, P: Response of Larval Amphibians to Perchlorate Contaminated Pond Water

Perchlorate occurs in ground and surface waters as a result of ammonium perchlorate (AP) discharge from rocket fuel. Perchlorate also has been used to experimentally manipulate amphibian metamorphosis, although usually at concentrations much greater than reported in contaminated waters. Recently, surface waters at Longhorn Army Ammunition Plant (LHAAP) in Karnack, TX were found to contain perchlorate levels at concentrations known to prevent metamorphosis in the frog, Xenopus laevis. Whether native amphibian species inhabiting AP-contaminated sites are affected is unknown. We examined development in tadpoles from AP-exposed sites at LHAAP and tested AP-contaminated pond water in the USEPA Tier 1 screening test for frog metamorphosis. Pond water containing over 1 ppm perchlorate had no effect on tail resorption in the frog metamorphosis assay. Bullfrog tadpoles collected from a reference site at LHAAP exhibited normal developmental features. In contrast, tadpoles collected from the AP contaminated site exhibited a 5-fold lower hindlimb/snout-vent length ratio than tadpoles from the reference site. We conclude that short-term exposure to AP late in larval life has minimal impact on metamorphosis. In contrast, tadpoles exposed to AP throughout larval life exhibit delayed development of thyroid-hormone sensitive structures. (The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements; either expressed or implied, of the 311 HSW/AFIERA or the U.S. Government. Supported in part by the U.S. Department of Defense, through SERDP under a Cooperative Agreement with the USAF, Inst. for Environ, Safety, and Occup. Health, Brooks AFB, TX).