Morphological Abnormalities in Frogs on National Wildlife Refuges in Alaska

The Kenai Frog Research Advisory Working Group (K-FRAWG) is a technical advisory committee assisting with a study of the factors contributing to abnormalities in wood frogs (Rana sylvatica) on the Kenai National Wildlife Refuge in southern Alaska. The study is being coordinated by the Environmental Contaminants Branch of the U.S. Fish and Wildlife Service (USFWS) in Anchorage. In addition to the University of California - Riverside, scientists and biologists from the United States Geological Survey (USGS) Columbia Environmental Research Center (Columbia, MO), USGS National Wetlands Research Center (Lafayette, LA), University of Wisconsin - LaCrosse, USGS- ASC Genetics Laboratory (Anchorage, AK), USFWS Ecological Services-Contaminants Program and the USFWS Kenai National Wildlife Refuge are participating in this multidisciplinary project.

The USFWS is assessing amphibian deformities on refuge lands across the U.S. In Alaska, the incidence of frog abnormalities has been studied on the Kenai National Wildlife Refuge (NWR), Arctic NWR, Yukon Delta NWR and Tetlin NWR. Viable frog ponds (8-20 ponds per refuge) have been monitored during the period of tadpole development (approximately May through July) since 2000. The highest incidence of abnormalities among the refuges (annual average for 2000 to 2003: 6-10% of metamorphs; incidence of abnormalities as high as 19% for particular ponds) studied in Alaska was observed at the Kenai NWR.

The goals of the project are to identify the factors contributing to the high incidence of abnormalities in metamorph wood frogs and to help revise management policies for the Kenai NWR. The project addresses the third phase of the USFWS’s National Abnormal Amphibian Project that began in 1997: Phase I – Observation and assessment, Phase II – Stressor identification, Phase III – Cause and effect linkages and management recommendations.

Possible causes of abnormalities in wood frogs on the Kenai NWR include predators, disease/parasites, environmental change, contaminants, and nutrition. The relative importance of each factor and potential synergisms among the factors remain to be determined. Known contaminants on the refuge include PCBs, petroleum, metals and herbicides/defoliants. Oil and natural gas exploration occurs on the Kenai NWR. The productivity of wells has declined during the last decade and, depending on the location of the oil/gas field on the refuge and the resource, extraction is predicted to cease over the next 5 to 15 years. In addition to identifying the causative agents of abnormalities in the frogs, the results from this 3-year study will assist with the development of Kenai’s Comprehensive Conservation Plan (CCP) which will include discussions of what to do with oil and gas fields after operations have closed.