Physical and biological coupling in eddies in the lee of the South-West Indian Ridge

Ansorge, I.J. and Pakhomov, E.A. and Kaehler, S. and Lutjeharms, J.R.E. and Durgadoo, J.V. (2010) Physical and biological coupling in eddies in the lee of the South-West Indian Ridge. Polar Biology, 33 (6). pp. 747-759. ISSN 0722-4060



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Eddies have some decisive functions in the dynamics of the Southern Ocean ecosystems. This is particularly true in the Indian sector of the Southern Ocean, where a region of unusually high-mesoscale variability has been observed in the vicinity of the South-West Indian Ridge. In April 2003, three eddies were studied: eddy A, a recently spawned anticyclone south of the Antarctic Polar Front (APF),; eddy B, an anticyclone north of lying between the Subantarctic Front and the APF; and eddy C, a cyclone north of the APF west of the ridge. Elevated concentrations of total Chl-a coincided with the edges of the cyclonic eddy, whereas both anticyclonic eddies A and B were characterised by low total Chl-a concentrations. Biologically, the two anticyclonic eddies A and B were distinctly different in their biogeographic origin. The zooplankton community in the larger anticyclonic eddy A was similar in composition to the Antarctic Polar Frontal Zone (APFZ) community with an addition of some Antarctic species suggesting an origin just north of the APF. In contrast, the species composition within the second anticyclonic eddy B appeared to be more typical of the transitional nature of the APFZ, comprising species of both subantarctic and subtropical origin and thus influenced by intrusions of water masses from both north and south of the Subantarctic Front. Back-tracking of these features shows that the biological composition clearly demarcates the hydrographic origin of these features.

Item Type:Article
Additional Information:The original publication is available at
Uncontrolled Keywords:Southern Ocean; Eddy; Eddies; Subantarctic Front; Antarctic Polar Frontal Zone; Zooplankton and micronekton communities
Subjects:G Geography. Anthropology. Recreation > GC Oceanography
Divisions:Faculty > Faculty of Science > Botany
ID Code:1724
Deposited By: Mrs Eileen Shepherd
Deposited On:05 Jan 2012 14:15
Last Modified:06 Jan 2012 16:21
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