ALL ABSTRACTS BY AUTHOR ABSTRACTS FOR THIS SESSION
Arctic
Science 2000 - Crossing Borders: Science and Community
Whitehorse, Yukon, Canada, Sept 21-24 2000
American Association for the Advancement of Science & Yukon Science Institute
Do Parasites Regulate Svalbard Reindeer?
S.D. Albon, R.J. Irvine (3rd author), A. Stien (6th author) (CEH Banchory, Hill of Brathens, Banchory, Aberdeenshire, AB31 4BW, UK; 0044 1330 826303/335/336; e-mail: s.albon@ceh.ac.uk, ji@ceh.ac.uk, aus@ceh.ac.uk)
O. Halvorsen (Zoological Museum, University of Oslo, Sars Gate 1, N-0562 Oslo, Norway; 0047 2285 1675; e-mail: odd.halvorsen@toyen,uio.no)
R. Langvatn (University Courses in Svalbard, Longyearbyen N-9170, Svalbard, Norway; 0047 7902 3351; e-mail: rolfl@unis.no)
E.Ropstad (Norwegian College of Veterinary Medicine, Ullevasveien 72, PO Box 8146, N-0033 Oslo, Norway; 0047 2296 4857; e-mail: Erik.Ropstad@veths.no)
Svalbard reindeer (Rangifer tarandus platyrhynchus) are non-migratory, occur in small (<10) groups but at comparatively high densities that fluctuate two-fold between years. Although they have no large predators, gastro-intestinal parasite nematodes, (principally Ostertagia gruehneri and Marshallagia marshalli) reach an abundance that depresses reindeer body condition. Compared to controls, treatment with anti-helminth drugs in April/May significantly increased the probability of individuals being pregnant twelve months later but had little effect on over-winter survival. Pregnancy in untreated, control animals, was significantly related to body weight, and independently to the intensity of infection with O. gruehneri, but not M. marshalli. Interestingly, the development of infection differs between nematode species. O. gruehneri is very low until the second summer of a reindeer’s life, compared to the apparently non-pathogenic M. marshalli which reaches adult burdens by the first autumn. These differences in the ontogeny of infection reflect differences in the life history patterns and transmission dynamics of the two species. They are consistent with the two-year time lag between O. gruehneri abundance and reindeer host abundance and thus a potential mechanism for explaining the instability of reindeer numbers.