Trypanosome occurrence and prevalence in the marine leech Johanssonia arctica and its host preferences in the northwestern Atlantic Ocean

• Published in: Canadian Journal of Zoology
• Main Author: Khan, R. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1991
• Subjects: Leech; Newfoundland
• Online Access: http://dx.doi.org/10.1139/z91-334; http://www.nrcresearchpress.com/doi/pdf/10.1139/z91-334

In this study, the distribution, abundance, host selection, and prevalence of trypanosomes in the marine leech Johanssonia arctica in the northwestern Atlantic were investigated. This leech is widely distributed and is encountered more often in the Labrador – northeastern Newfoundland area, especially at depths of 165 m or more, where water temperatures of about 0 °C prevail. It rarely occurs south and west of Newfoundland, where warmer bottom temperatures occur. The highest prevalence of the trypanosome (Trypanosoma murmanensis) infection was found in leeches collected from a depth of 165 m in summer off the Labrador and north and east Newfoundland coasts in the largest leeches (~25 mm). Samples taken at 3- to 5-month intervals in Conception Bay over a 7-year period showed that prevalence of the trypanosome infection is also greater in summer–autumn than during winter. The leeches sampled had fed predominantly on pleuronectiform (flatfish) rather than perciform or gadiform fish, and rarely on elasmobranchs. High prevalences of T. murmanensis in fish coincide with the abundance of J. arctica in several areas of the northwestern Atlantic. Since six other species of marine leeches apparently do not acquire trypanosome infections after feeding on infected fish, J. arctica is probably the major vector of the parasite in the northwestern Atlantic north of latitude 45°N.