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Oceanography of the subantarctic and Polar Frontal Zones south of Australia during summer: Setting for the SAZ-Sense study

journal contribution
posted on 2023-05-17, 11:07 authored by Andrew BowieAndrew Bowie, Griffiths, FB, Dehairs, F, Trull, TW
This paper provides a description of the physical and chemical properties (temperature, salinity, macro-nutrient, and oxygen concentrations) and bulk biomass indicators (chlorophyll and beam attenuation) prevailing in the subantarctic zone and polar front zones south of Tasmania (Australia) during the ‘Sensitivity of the subantarctic zone to environmental change’ (SAZ-Sense) expedition carried out in the austral summer of 2007. Phytoplankton biomass showed a characteristic north–south gradient of decreasing chlorophyll from the subantarctic zone to Polar Frontal Zone, as well as a zonal gradient in the northern subantarctic zone, with an increase in chlorophyll from southwest to southeast of Tasmania. The representativeness of the observations was assessed by comparison to previous studies including satellite observation of chlorophyll biomass over a 10-year period. We consider the possible role of spatial differences in: (i) ocean water masses and frontal systems, (ii) upper mixed layer stratification at three process stations, and (iii) nutrient availability, in controlling the observed variations in phytoplankton biomass in the region. Zonal gradients of the basic oceanographic physical and chemical conditions in the subantarctic zone were relatively small and therefore unlikely to control the three-fold west-to-east differences observed in the accumulation of phytoplankton biomass. The zonal variation in subantarctic zone chlorophyll biomass appears to be driven at least partly by greater micro-nutrient (iron) supply to the waters east of Tasmania, as reported also by others ( [2] and [30]). Despite this condition, the region of higher phytoplankton biomass to the southeast of Tasmania was only marginally more productive than the region of lower biomass west of Tasmania and south of the polar front, and exported less particulate carbon than the lower biomass waters (Jacquet et al., 2011).

History

Publication title

Deep-Sea Research. Part 2: Topical Studies in Oceanography

Volume

58

Issue

21-22

Pagination

2059-2070

ISSN

0967-0645

Department/School

Institute for Marine and Antarctic Studies

Publisher

Pergamon-Elsevier Science Ltd

Place of publication

The Boulevard, Langford Lane, Kidlington, Oxford, England, Ox5 1Gb

Rights statement

The definitive version is available at http://www.sciencedirect.com

Repository Status

  • Restricted

Socio-economic Objectives

Antarctic and Southern Ocean oceanic processes

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