Seasonal and spatial dynamics of iron availability in the Scotia Sea

Autor: Rebecca E. Korb, Daria J. Hinz, Michael J. Whitehouse, C. Mark Moore, Richard Sanders, Maria C. Nielsdóttir, Thomas S. Bibby, Eric P. Achterberg
Rok vydání: 2012
Předmět:
Zdroj: Marine Chemistry. :62-72
ISSN: 0304-4203
DOI: 10.1016/j.marchem.2011.12.004
Popis: The Southern Ocean is the world's largest high nutrient low chlorophyll (HNLC) region. However, satellite images highlight several areas associated with island chains and shallow topographic features which display high phytoplankton biomass. Here we present the first study of seasonal variations in phytoplankton biomass and iron availability in the Scotia Sea over both austral spring and summer seasons. Based on dissolved iron (dFe) and Chlorophyll a (Chl a) concentrations, the study area is be divided into three regions: North of South Georgia, south of South Georgia and the vicinity of South Orkney Islands. The Scotia Sea to the south of South Georgia exhibited low dFe concentrations ( 0.05). Nitrate concentrations were 16 mu M lower in summer compared to spring, whilst Chl a standing stocks remained high. Enhanced dFe (similar to 0.25 nM) and Chl a concentrations were furthermore observed in the vicinity of the South Orkney Islands, located in the southern Scotia Sea. Iron addition experiments showed that in situ phytoplankton were iron replete spring and summer north of South Georgia and in the vicinity of South Orkney Islands during summer. We thus suggest that increased iron supply in high productivity areas including the area north of South Georgia and the South Orkney Islands, was sustained by a continuous benthic supply from their shelf systems, with a potential additional input from seasonally retreating sea ice in the South Orkney system
Databáze: OpenAIRE
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