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Parasitic infection of the hyperiid amphipod Themisto libellula in the Canadian Beaufort Sea (Arctic Ocean), with a description of Ganymedes themistos sp. n. (Apicomplexa, Eugregarinorida)

Prokopowicz, Anna J.; Rueckert, Sonja; Leander, Brian S.; Michaud, Jos�e; Fortier, Louis


Anna J. Prokopowicz

Brian S. Leander

Jos�e Michaud

Louis Fortier


Two parasites were found in the hyperiid amphipod Themisto libellula sampled with nets and collected by sediment traps over the annual cycle in the Canadian Beaufort Sea. The trophozoites of the newly described gregarine Ganymedes themistos sp. n. infected the digestive tract of 60.2% of the T. libellula analyzed from net collections. An unidentified ciliate infected the body cavity of 4.4% of amphipods. G. themistos possessed the ball-like structure at the anterior end and the cup-like invagination at the posterior end that are typical of the genus Ganymedes. The frequency and severity (number of parasites host−1) of infection by G. themistos increased with the length of T. libellula in the range 8–20 mm, and leveled off at ca. 94% and 186 trophozoites host−1 on average in the range 20–34 mm. Spatially, gregarine infection was less severe (63 ± 100 G. themistos host−1) on the Slope than on the Mackenzie Shelf (110 ± 160) and in the Amundsen Gulf (132 ± 157). No evidence of an impact of trophozoite infection on the feeding and sexual maturation of the host was found. For a given size of T. libellula, infection by both parasites was more frequent in the traps than in the nets (G. themistos: 91.0% vs. 82.7%; ciliates: 16.3% vs. 6%). The 2.7 times higher infection frequency in the traps suggested that the ciliate parasite may kill its host

Journal Article Type Article
Online Publication Date May 20, 2010
Publication Date 2010-10
Deposit Date Sep 26, 2013
Print ISSN 0722-4060
Electronic ISSN 1432-2056
Publisher BMC
Peer Reviewed Peer Reviewed
Volume 33
Issue 10
Pages 1339-1350
Keywords General Agricultural and Biological Sciences
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