Infections of Diphyllobothrium dendriticum, D. ditremum (Cestoda), and Cystidicola farionis (Nematoda) in a north Norwegian population of Arctic charr (Salvelinus alpinus) during winter
نویسنده
چکیده
KNUDSEN, R. and KLEMETSEN, A. 1994. Infections of Diphyllobothrium dendriticum, D. ditremum (Cestoda), and Cystidicola farionis (Nematoda) in a north Norwegian population of Arctic charr (Salvelinus alpinus) during winter. Can. J. Zool. 72: 1922-1930. Infections of the parasites Diphyllobothrium dendriticum, Diphyllobothrium ditremum, and Cystidicola farionis in Arctic charr (Salvelinus alpinus) from Takvatn, northern Norway, were followed throughout a 9-month overwintering period. The relative density of all three parasite species increased with the age of the host in response to ontogenetic shifts in habitat and food of Arctic charr in the lake. Our results indicate that some recruitment of the three parasite species, particularly D. ditremum, takes place during the winter. However, winter parasite recruitment was lower than in the ice-free season. In spite of high parasite infection in some individuals, no strong indications of parasite-induced host winter mortality were found for any of the three species. Low overwintering mortality of heavily parasitized charr may be connected with a stock-reduction program in the lake that has improved the conditions of the fish, and the residual stock is probably less affected by parasites.
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