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Journal of Marine Biology
Volume 2010, Article ID 410129, 18 pages
http://dx.doi.org/10.1155/2010/410129
Review Article

Long-Term Relationships between the Marine Environment, Krill and Salps in the Southern Ocean

1Department of Earth and Ocean Sciences, 6339 Stores Road, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
2Laboratory of Fisheries Oceanography, Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, 120 Gangneung Daehangno, Gangneung 210-702, Republic of Korea
3British Antarctic Survey, Natural Environment Research Council, High Cross, Cambridge CB3 OET, UK
4Sea Fisheries Institute, Palmaille 9, 22767 Hamburg, Germany

Received 1 June 2010; Revised 5 August 2010; Accepted 21 November 2010

Academic Editor: Wen-Xiong Wang

Copyright © 2010 Chung Il Lee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Long-term variations (1975–2002) in climatology of marine environmental parameters, Antarctic krill, Euphausia superba, and the pelagic tunicate, Salpa thompsoni, were compared within the Atlantic Sector of the Southern Ocean. Sea water temperature in the top 400 m increased at a rate of 0.020–0.030°C ⋅ yr−1, which was accompanied by the dissolved oxygen decline. Top 100 m water layer became fresher with lower concentrations of phosphates and nitrates, while at subsurface layers (200–400 m) both salinity and nutrients showed small increasing trend. Unlike phosphates and nitrates, silicate concentrations decreased in the entire water column. Shorter-term water temperature dynamics closely correlated with the El Nino events expressed as the Southern Oscillation Index which in turn was linked to the propagation of the Antarctic Circumpolar Wave (ACW). The variations of sea-ice extent matched well the changes in both air and water temperatures. In general, abundance of krill and salps showed opposite to each other trends. Due to large area considered in this study, no significant relationships between abiotic factors and both krill and salps were found. However, our analysis demonstrated that krill abundance was greater in years with lower sea water temperature, greater sea-ice extent and higher nutrient concentration, while salps showed the opposite pattern.