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NOAA Technical Memorandum NMFS-NWFSC-8

Contaminant Exposure and Associated Biological Effects in Juvenile Chinook Salmon (Oncorhynchus tshawytscha) from Urban and Nonurban Estuaries of Puget Sound

Usha Varanasi, Edmundo Casillas, Mary R. Arkoosh,
Tom Hom, David A. Misitano, Donald W. Brown,
Sin-Lam Chan, Tracy K. Collier, Bruce B. McCain,
and John E. Stein

National Marine Fisheries Service
Northwest Fisheries Science Center
Environmental Conservation Division
2725 Montlake Blvd. E., Seattle, WA 98112

April 1993

Ronald H. Brown, Secretary

National Oceanic and Atmospheric Administration
John A. Knauss, Administrator

National Marine Fisheries Service
William W. Fox, Jr., Assistant Administrator for Fisheries

Contributing Scientific Investigators

Douglas G. Burrows

Ethan Clemons

Susan M. Pierce

Paul D. Plesha

William L. Reichert

Karen L. Tilbury

Douglas Weber

Catherine A. Wigren


This report presents and interprets the results of chemical, biochemical, and biological studies on juvenile chinook salmon (Oncorhynchus tshawytscha) outmigrating from urban and nonurban estuaries of Puget Sound, Washington. These studies were conducted between 1989 and 1991 by the National Marine Fisheries Service (NMFS) of the National Oceanic and Atmospheric Administration (NOAA) with sponsorship from the Environmental Protection Agency, Region 10 and NMFS/NOAA. The objective of these studies was to determine the degree of chemical exposure to juvenile chinook salmon as they migrate through urban-associated compared to nonurban estuaries and to evaluate the effects of chemical contaminant exposure on these animals.Urban estuaries studied included the Duwamish Waterway entering Elliott Bay near Seattle, Washington, the Puyallup River entering Commencement Bay near Tacoma, Washington, and the Snohomish River entering Port Gardner Bay near Everett, Washington. Sediments in these aquatic urban environments are known to be highly contaminated, although the sediments from the Duwamish Waterway and the Puyallup estuary, particularly in the waterways, are significantly more contaminated than sediments in the Snohomish estuary. Additionally, juvenile chinook salmon from the Nisqually River estuary, a minimally contaminated nonurban estuary, and from the respective hatcheries of each of the waterways and rivers mentioned above were sampled as reference fish.

The chemical indicators of contaminant exposure include levels of hepatic polychlorinated biphenyls (PCBs) and biliary levels of fluorescent aromatic compounds (FACs), which are semiquantitative measures of exposure to aromatic hydrocarbons (AHs). Stomach contents of juvenile salmon were also analyzed for selected AHs and chlorinated hydrocarbons (CHs) to assess the importance of diet as a possible route of uptake of xenobiotics from polluted estuaries. The study also included measurement of early physiological and biochemical (bioindicator) responses to chemical contaminant exposure. These bioindicators have been shown to reflect the degree of exposure to particular contaminants as well as to indicate some of the biological consequences of chemical exposure. In addition to the chemical indicators, biochemical measures of contaminant-induced responses of the hepatic enzyme system and genotoxic damage were assessed. Measures of the hepatic cytochrome P-450 system included hepatic aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin-O-deethylase (EROD) activities. Hepatic levels of DNA-xenobiotic adducts, detected by 32P-postlabeling, were measured as a bioindicator of genetic damage. Biological parameters that demonstrate the effects of chemical contaminant exposure were also measured. Initially, considerable effort was expended in understanding and enhancing our fish maintenance and husbandry practices. This allowed us to maintain healthy fish in saltwater for periods of months, which was critical for studies on depuration and measurement of biological effects. Biological effects that were monitored included effects on immune function and effects on growth and long-term survival of juvenile salmon. Alterations in immune function have been shown to be a sensitive index on the effects of contaminants. Suppression of immune function can seriously affect the ability of salmon to face the stresses posed in the saltwater environment. Similarly, effects on growth and survival are more classical measurements on the effects of chemical contaminants; negative effects are more easily interpreted as detrimental to the individual and thus eventually to the population.

Significant Findings

Overall, these results demonstrate that increased chemical contaminant exposure in juvenile chinook salmon during their brief residency in urban estuaries of Puget Sound, Washington, was sufficient to elicit reponses at the chemical, biochemical, and biological level. Measurements of this type provide evidence of linkage between complex mixtures of chemical contaminants in the environment and effects on health and survival of fish. This information will be critical in increasing our capabilities for assessing the full spectrum of effects on salmon resulting from exposure to the myriad anthropogenic chemicals that can be present in the near coastal environment. The detection of chronic effects requires sensitive and reliable tools that cover a broad range of important biological functions and that are both cost-effective in their application and amenable for use in studies as described here. The availability of such tools would allow generation of sufficient data to identify and statistically quantify potential risk factors in the etiology of effects observed in fish from contaminated coastal environments.


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