Metazoan parasite infections in landlocked and anadromous Arctic charr (Salvelinus alpinus Linnaeus), and their use as indicators of movement to sea in young anadromous charr

Eighteen genera of metazoan parasites (Monogenea, 1; Digenea, 7; Cestoda, 4; Nematoda, 4; Acanthocephala, 1; Copepoda, 1) were collected from 172 landlocked and anadromous Arctic charr (Salvelinus alpinus Linnaeus) in northern Labrador. Four species (Lecithaster gibbosus, Diphyllobothrium dendriticum, Diphyllobothrium ditremum, and Salmincola carpionis) and one genus (Tetraonchus) have not previously been reported from Arctic charr in Labrador. The dominant parasites in the landlocked charr were Diplostomum sp., Crepidostomum farionis, and Diphyllobothrium ditremum. In the sea-run charr, Bothrimonus sturionis and Brachyphallus crenatus were dominant. Regression analyses indicated that the numbers of parasites were significantly correlated with host age (P < 0.001) for these species. All landlocked charr sampled were infected with parasites by age 1+ years whereas all sea-run charr were infected by age 3+. At 1+ years, 43% of the Arctic charr collected in the Ikarut River were infected with marine or brackish-water parasites, suggesting that some young charr, not yet ready for the annual seaward migration, may make short feeding excursions into salt water.

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REGULAR ARTICLES / ARTICLES RÉGULIERS Whether to reproduce or not: immune suppression and costs of parasites during reproduction in the Arctic charr

Canadian Journal of Zoology ◽

10.1139/z00-193 ◽

2001 ◽

Vol 79 (2) ◽

pp. 271-278 ◽

Cited By ~ 48

Author(s):

Frode Skarstein ◽

Ivar Folstad ◽

Ståle Liljedal

Keyword(s):

Immune Suppression ◽

Salvelinus Alpinus ◽

Arctic Charr ◽

Indirect Evidence ◽

The Arctic ◽

Parasitic Infections ◽

Intermediate Hosts ◽

Parasite Infections ◽

Gamete Production ◽

The Difference

Secondary sexual characters are assumed to be costly to develop, and the costs of parasite infections and immune suppression are currently an active area of research within sexual selection. We investigated differences in parasitic infections and immunological activity between reproductively active and inactive Arctic charr (Salvelinus alpinus). Spawning fish were found to have higher intensities of macroparasite infections than nonspawning or resting fish. The difference in intensity between spawning and resting fish was only observed in males, and can be explained by differences in exposure or susceptibility to parasites. However, there is indirect evidence that the difference in parasite intensities does not stem from varying exposure originating from group differences in consumption of carotenoid-containing intermediate hosts. We show, rather, that spawning males may be more susceptible, since they have a smaller spleen, which is an important lymphocyte-producing organ, than resting males. As these costs of spawning are found predominantly among males, they are unlikely to be the result of energetic investment in gamete production, as gamete production in general is thought to be more energetically demanding in females than in males. Rather, we suggest that the observed costs of reproduction result from immune suppression related to ornamental development and spermatogenesis.

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