ORGANOCHLORINE CONTAMINANTS IN DOUBLE-CRESTED CORMORANTS FROM LEWIS AND CLARK NATIONAL WILDLIFE REFUGE IN THE COLUMBIA RIVER ESTUARY FINAL REPORT Project ID: 13420-1261-1N14

The Columbia River receives numerous contaminants from permitted municipal and industrial discharges, nonpoint pollution, accidental spills, and hazardous waste sites. Studies by the U.S. Fish and Wildlife Service and others have documented bioaccumulation of organochlorine contaminants in fish and wildlife in or along the river, and these compounds have been associated with poor reproductive success in resident bald eagles (Haliaeetus leucocephalus). Elsewhere in the United States, double-crested cormorants (Phalacrocorax auritus) have been used as indicators of exposure to organochlorine compounds. The Columbia River estuary supports an estimated 6,620 breeding cormorant pairs which are exposed to, and potentially harmed by, organochlorine contaminants. Between 1990 and 1995, we collected cormorant eggs from two islands along the lower Columbia River, and in 1993 from a reference colony off the coast of southern Oregon. Eggs were chemically analyzed for organochlorine pesticides, total mercury, polychlorinated biphenyls (PCBs), dioxins, and furans. Extracts from some eggs were also used in a H4IIE rat hepatoma bioassay to assess exposure to planar halogenated hydrocarbons (dioxin-like compounds). Concentrations of p,pN-DDE and total PCBs in eggs from the reference colony were lower than in eggs from the Columbia River colonies. Concentrations of dioxins and furans in 1993 eggs were elevated in the lower Columba River colonies, but below detection limits at the reference colony. Concentrations of nearly all chemical constituents in the lower Columbia River eggs appeared higher at the upriver colony at Rice Island than at the colony located near the mouth of the river on East Sand Island, and some contaminants were significantly higher. Some eggs of lower Columbia River cormorants exhibited eggshell thinning, and concentrations of p,pN-DDE in eggs were correlated (r= -0.47, P=0.001, n=46) to eggshell thickness. The toxicity of the dioxin-like compounds, measured as toxic equivalents (TEQs), in some Columbia River cormorant eggs approached or exceeded threshold effects levels or concentrations associated with reproductive impacts in some sensitive species. Results of the H4IIE-extract bioassay conducted on eggs in 1993 and 1994 indicated as much as 24% egg mortality could occur at Columbia River colonies when compared to concentration-response relationships for cormorants in the Great Lakes. Results indicated that concentrations of organochlorine chemicals could impact developing embryos or elicit egg mortality in some individuals, but concentrations were near estimated no-effect levels and did not approach levels considered to impact the population.