Histology of Sculpin spp. in East Greenland. II. Histopathology and trace element concentrations

Abstract

For many years, the sculpin has been utilized as a sentinel monitoring species for anthropogenic impacts on the marine environment. To further develop its potential as a screening model body burden of several trace elements, including cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb) and selenium (Se), were investigated. In addition, histopathology in shorthorn sculpins (Myoxocephalus scorpius; n?=?20) and fourhorn sculpins (Myoxocephalus quadricornis; n?=?10) were examined at three sites around the Scoresby Sound settlement in Central East Greenland. Fourhorn sculpins caught at the most distant site from the settlement, contained significantly higher hepatic Cu and Cd concentrations as well as significantly elevated gill Pb levels compared to the shorthorn sculpins collected at two other sites closer to the settlement. Histological examinations showed that fish with significantly higher concentrations of hepatic Cd and Se exhibited greater nuclear alterations, interstitial hyperplasia/hypertrophy, interstitial mononuclear infiltrations and granulomas. Further, fish with higher Cd and Cu gill tissue levels displayed a significantly higher number of cytoplasmic alterations and lamellar epithelium lifting, hypertrophic and hyperplastic epithelium along with mucus cell hyperplasia. While the presence of liver lesions were not species or sex-specific, the presence of gill lesions decreased in the order female fourhorn sculpins?>?female shorthorn sculpins?>?male fourhorn sculpins?>?male shorthorn sculpins. Hepatic Hg concentrations exceeded known lowest observable effect doses (LOED) for fish (0.1–0.5?μg g^?1 ww) in 27% of fish, while liver Cd residues in 80% exceeded LOED (0.42–1.8?μg g^?1 ww). Based upon these results, data suggest that using the sculpin as a valuable sentinel fish species histopathology may serve as a reliable tool for assessing marine ecosystem exposure to trace metals. However, confounding physiological and ecological factors also need to be considered.