DETECTING EXPOSURE TO SURFACE WATER CONTAMINANTS NON-LETHALLY USING ATLANTIC SALMON (SALMO SALAR) SCALES

There is a great need for non-lethal ways to assess the effects of pollutants on threatened and endangered fish species. Evidence suggests that fish scales biologically respond to various pollutants. Scales can be removed without causing pain or injury to the fish and scales regenerate on the fish after they are removed. Therefore, fish scales could serve as non-lethal, rapid screening tools to assess pollutant exposure. I investigated two biomarkers (indicators of pollutant exposure) in scales: one for organic pollutants (such as oil and polychlorinated biphenyls (PCBs)) and one for hormones (such as the female hormone, estrogen). I hypothesized that the expression of these biomarkers would be higher in the scales of fish exposed to pollutants than in scales from untreated fish. To test this idea, I exposed Atlantic salmon (Salmo salar) juveniles to PCBs and to an estrogenic hormone in water for 2 – 4 days. My results demonstrate that the expression of the biomarker for organic pollutants was increased in scales of fish exposed to PCBs, while the expression of the biomarker for hormones did not increase in scales of fish exposed to estrogen. I conclude that it is plausible that fish scales could serve as non-lethal, rapid screening tools to assess exposure to some pollutants, but that more research needs to be conducted to evaluate other possible biomarkers and assess biomarker response in contaminant mixtures as are typically found in rivers and other waterbodies, before fish scales can be utilized as pollutant screening tools in the field.