Sublethal effects of chronic exposure to an organochlorine compound on northern leopard frog (Rana pipiens) tadpoles

Global contamination with organochlorine compounds (OCs) has posed developm ental and reproductive problems in wildlife worldwide. However, little is k nown about the impact of OCs or other pollutants on amphibians, despite mou nting concerns about amphibian population declines and developmental deform ities in the wild. Wildlife populations may be affected critically by suble thal impacts of anthropogenic disturbances, yet little research has focused on such effects in amphibians. In the current study, northern leopard frog (Rana pipiens) tadpoles were chronically exposed to a polychlorinated biph enyl (PCB) congener, 77-TCB, and effects on behavior, morphology, competiti ve performance, and corticosterone content were determined. R. pipiens acti vity levels and feeding rates were decreased by 77-TCB exposure, but morpho logy of mouthparts and body proportions were unaffected. 77-TCB enhanced gr owth and altered competitive interactions between R. pipiens and wood frog (Rana sylvatica) tadpoles. R, pipiens tadpoles exposed to 77-TCB showed dec reased whole-body corticosterone content compared to controls both before a nd after injection with adrenocorticotropic hormone (ACTH). All of the fact ors examined in the current study play critical roles in tadpole developmen t, growth, survivorship, and eventual reproductive success, suggesting nega tive population-level consequences for amphibians in PCB-contaminated habit ats. (C) 2001 by John Wiley & Sons, Inc.