Susceptibility of marine fish to trypanosomes

Abstract

Trypanosomes, some of similar morphology and morphometry, were observed in the blood of seven species of marine teleosts (Pleuronectiformes: American plaice (Hippoglossoides platessoides), yellowtail flounder (Limanda ferruginea), and grey sole (Glyptocephalus cynoglossus); Perciformes: Arctic eelpout (Lycodes reticulatus), spotted wolffish (Anarhichas minor), striped wolffish (A. lupus), and polka-dot seasnail (Liparis cyclostigma)) collected off coastal Newfoundland, Canada. Experiments to ascertain specificity or susceptibility of the trypanosomes were initiated using leeches as vectors. Trypanosomes from pleuronectiform and perciform fish were equally infective to taxonomically related and unrelated species, including a gadiform fish, the Atlantic cod (Gadus morhua). Moreover, Trypanosoma murmanensis of the cod was transmitted to pleuronectiform, perciform, anguilliform, and gadiform fish. No marine fish species tested was insusceptible to trypanosomes isolated from the different hosts. In all fish, there was a progessive increase in size with time, reaching the maximum by 60 days postinfection. No striking differences in morphology or morphometry were apparent among the trypanosomes in recipient fish regardless of host origin. The opinion is expressed that the trypanosomes of these marine fish, which have overlapping geographical distributions, belong to a single species, referrable to T. murmanensis Nikitin, 1927.