INFLUENCE OF CONCURRENT EXPOSURE TO CRUDE-OIL AND INFECTION WITH TRYPANOSOMA-MURMANENSIS (PROTOZOA, MASTIGOPHORA) ON MORTALITY IN WINTER FLOUNDER, PSEUDOPLEURONECTES-AMERICANUS

A study was conducted to determine the influence of concurrent exposure to crude oil and a hemoprotozoan parasite, Trypanosoma murmanensis, on mortality in winter flounder, Pseudopleuronectes americanus. Both juvenile and adult flounder were infected and exposed to sediment contaminated with various concentrations (approximately 100, 300, 600, 1000, and 2200-mu-g/g) of oil for 8 weeks at 0-1-degrees-C in flow-through seawater aquaria with corresponding uncontaminated infected and uninfected groups. Mortality occurred earlier and was greater in juvenile fish exposed to crude oil than in adults. However, a larger percentage of oil-treated, infected adult flounder died after exposure at the highest concentrations. At the highest concentrations, selected organ somatic indices and blood values in surviving flounder were affected more in the infected, oil-treated fish than in corresponding controls. The prolonged period of patency of T. murmanensis in the oil-treated groups might be associated with immunosuppression.