INFLUENCE OF CRUDE-OIL AND PULP AND PAPER-MILL EFFLUENT ON MIXED INFECTIONS OF TRICHODINA-COTTIDARIUM AND T-SAINTJOHNSI (CILIOPHORA) PARASITIZING MYOXOCEPHALUS-OCTODECEMSPINOSUS AND M-SCORPIUS

Samples of longhorn sculpin (Myoxocephalus octodecemspinosus) were exp osed to sediment contaminated with crude oil or pulp and paper mill ef fluent for periods up to 13 months in the laboratory. Other samples we re collected at sites where crude oil or effluent from a pulp and pape r mill are discharged. The intensity of gill infections of Trichodina spp. on exposed fish was significantly higher than on controls 5, 9, a nd 13 months after exposure. The intensity of the ciliates was also gr eater on sculpins collected near an oil-receiving terminal than on tho se sampled 5 km from the polluted site. Field collections of longhorn and shorthorn (Myoxocephalus scorpius) sculpins at and distant from a pulp and paper mill had high and low intensities of the ciliates, resp ectively. Similarly, the intensity of trichodinid ciliates was also si gnificantly greater in longhorn sculpins exposed to effluent-contamina ted sediment than in controls 5 months after exposure. The results sug gest that the intensity of gill-inhibiting species such as trichodinid s in susceptible fish hosts increases after chronic exposure to crude oil and to pulp and paper mill effluent, and the parasites may serve a s indicators of pollution.