Bioindicators of Stress in Winter Flounder, Pleuronectes americanus, Captured Adjacent to a Pulp and Paper Mill in St. George's Bay, Newfoundland

Abstract

Winter flounder, Pleuronectes americanus, inhabiting a marine inlet (Port Harmon) adjacent to a pulp and paper mill, and from a reference site (St. George's) 12 km away, were examined for signs of stress. Fish from Port Harmon showed significantly lower condition (k) factors, hepatosomatic indices, blood haemoglobin, and lymphocyte levels, than those from the reference site. Delayed spawning or spermiation were evident in female and male flounder, respectively, from Port Harmon compared with those from St. George's. Prevalence and intensity of larval anisakid nematodes, metacercariae of the digenetic trematode, Cryptocotyle lingua, and cysts of the microsporan, Glugea stephani, were significantly higher at Port Harmon than at St. George's, whereas prevalence and intensity of an intestinal acanthocephalan were significantly lower at Port Harmon. The percentage of flounder with external lesions (fin necrosis, ulcers) was significantly higher at Port Harmon than at St. George's. Anaemia, low lymphocyte levels, low somatic indices, high incidence of external lesions, and abnormal parasitic infestations are all suggestive of immunosuppression. Because basic water chemistry at the two sites was similar, the evidence of chronic stress observed in winter flounder from Port Harmon can most likely be attributed to pollutants from the effluent that have accumulated in the sediment.