Pelagic tunicates in the Lazarev Sea, Southern Ocean

E.A. Pakhomov¹, C.D. Dubischar², B.P.V. Hunt¹, V. Strass², B. Cisewski², V. Siegel³, L. von Harbou², L. Gurney¹, J. Kitchener⁴ and U. Bathmann²

¹Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, B.C., Canada, V6T 1Z4

²Alfred Wegener Institute of Polar and Marine Research, Am Handelshafen 12, 27515, Bremerhaven, Germany

³Sea Fisheries Institute, Palmaille 9, 22767 Hamburg, Germany

⁴Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia

Two species of salps, namely Salpa thompsoni and Ihlea racovitzai, are found south of the Antarctic Polar Front in the Southern Ocean. Both species have been sampled year around (December- January, April-May and July-August) in the Lazarev Sea during German SO-GLOBEC. S. thompsoni appeared to be advected into the area, has the highest concentrations during summer and fall disappearing during winter. The evidence points that S. thompsoni is not able to complete its life cycle in the area, suggesting that high Antarctic populations of S. thompsoni found during the summer season are likely ‘host populations’. I. racovitzai on the other hand has the lowest densities during summer increasing their numbers during fall and peaks in numbers during austral winter. This species sexually reproduced just before the area has been covered with the ice in the beginning of winter. Elemental composition measurements showed that despite both species are watery (water is ~ 93% of body mass), salps had relatively high carbon (up to 15%) and protein (up to 30%) contents of their remaining dry mass. Both elemental composition and life cycle characteristics are indirectly point that salps may be important prey items for both cold and warm blooded predators.

STATUS UPDATE:

08/21/09: Manuscript received and forwarded to editor for suggested reviewers.