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Marine Ecology Progress Series

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MEPS 119:291-297 (1995)  -  doi:10.3354/meps119291

Organic carbon transport from the Southern Ocean and bacterial growth in the Antarctic intermediate Water masses of the Tasman Sea

Moriarty, D. J. W., O'Donohue, M. J.

The concept that organic carbon is transported to the equatorial region at intermediate water depths from subantarctic frontal zones has been re-investigated using the tritiated thymidine method to determine rates of bacterial DNA synthesis in water masses of the Tasman Sea. There was a higher bacterial growth rate and thus a higher flux of organic carbon through bacteria in the Antarctic Intermediate Water (900 to 1000 m depth) than in the water masses immediately above or below in the Tasman Sea east and south of Tasmania. Values for bacterial production were 4 to 8 ug C m-3 d-1, which are equivalent to a consumption of about 3 to 6 ul O2 l-1 yr-1. In the deeper layer at 1200 to 1500 m, rates were 3 to 4 times lower. These rates are compatible with other data on oxygen utilisation. Our results support the concept that organic matter sinks with downwelling water in the zone between the Subtropical Convergence and the Polar Front in the Southern Ocean and is advected towards the equator below the photic zone.

Oceanic carbon cycling . Southern Ocean . Pacific Ocean . Bacteria

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