Physical and biological processes at the Subtropical Convergence in the South-west Indian Ocean

Froneman, P.W. and Ansorge, I.J. and Richoux, N. and Blake, J. and Daly, R. and Sterley, J. and Mostert, B. and Heyns, E. and Sheppard, J. and Kuyper, B. and Hart, N. and George, C. and Howard, J. and Mustafa, E. and Pey, F. and Lutjeharms, J.R.E. (2007) Physical and biological processes at the Subtropical Convergence in the South-west Indian Ocean. South African Journal of Science, 103 . pp. 193-195. ISSN 0038-2353




A detailed hydrographic and biological survey was conducted in the region of the Subtropical Convergence in the Indian sector of the Southern Ocean in April 2007. Hydrographic data revealed that the subsurface expression of the Subtropical Convergence (at 200 m), marked by the 10°C isotherm, appeared to meander considerably between 41°S and 42°15’S. Total surface chlorophyll- a concentration was low and ranged from 0.03 to 0.42 µg l–1 and was always dominated by the pico- (<2 µm) and nano- (2–120 µm) size classes, which contributed between 81% and 93% of the total pigment. The total chlorophyll-a integrated over the top 150m of the water column showed no distinct spatial trends, and ranged from 12.8 to 40.1mg chl-a m–2. There were no significant correlations between the total integrated chlorophyll- a concentration and temperature and salinity (P > 0.05). The zooplankton community was dominated, numerically and by biomass, by mesozooplankton comprising mainly copepods of the genera, Oithona,Paraeuchaeta, Pleuromamma, Calanus and Clausocalanus. An exception was recorded at those stations in the region of the front where the tunicate, Salpa thompsoni, dominated the total zooplankton biomass.

Item Type:Article
Uncontrolled Keywords:Sub-Antarctic; South-west Indian Ocean Subtropical Convergence Zone; Hydrographic surveys; Biological monitoring
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Zoology & Entomology
ID Code:847
Deposited By: Ms Vivien Botha
Deposited On:16 Nov 2007
Last Modified:06 Jan 2012 16:19
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