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Summertime mixed layer development in the marginal sea ice zone off the Mawson coast, East Antarctica


Williams, GD and Nicol, S and Raymond, B and Meiners, K, Summertime mixed layer development in the marginal sea ice zone off the Mawson coast, East Antarctica, Deep-Sea Research. Part 2: Topical Studies in Oceanography, 55, (3-4) pp. 365-376. ISSN 0967-0645 (2008) [Refereed Article]

DOI: doi:10.1016/j.dsr2.2007.11.007


Two small-scale Antarctic marine ecosystem surveys were conducted offshore from the Mawson coast (6166 degrees E), in the austral summers of January 2001 and 2003. Striking differences were observed in the state of the marine ecosystem between the surveys; in particular krill abundance and penguin breeding success were significantly lower in 2003. In this paper we examine the variability in the physical oceanography between the two surveys, and identify the development of the summer mixed layer (SML) as the key physical process influencing the differences in ecological conditions. The mixed layer in 2003 was warmer, fresher and reduced in both dissolved oxygen content and fluorescence relative to 2001. In 2001 the mean mixed-layer depth was 68.5 +/- 12.4m. In 2003, the mean mixed-layer depth was 33.8+/- 11.2m, and increased through the remaining 14 days of the survey. The SML in 2003 was underdeveloped by over a month relative to the 2001 hydrography and we relate this to the seasonal variability in the pattern and timing of sea-ice melt. AVHRR satellite images show a region of fast ice against the Mawson coast that had greater spatial and temporal extent in 2003. We conclude that delayed mixed layer development due to persistent sea ice is likely to have a negative impact on the marine ecosystem of the Antarctic shelf. This may have important implications for predicting the impact of future variability in the sea-ice growth/melt transition due to climate change.

Item Details

Item Type:Refereed Article
Keywords:East Antarctica; Mawson coast; summer mixed layer; physical-biological interactions; Antarctic Slope Current
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Williams, GD (Associate Professor Guy Williams)
UTAS Author:Nicol, S (Dr Stephen Nicol)
UTAS Author:Raymond, B (Dr Ben Raymond)
UTAS Author:Meiners, K (Dr Klaus Meiners)
ID Code:71383
Year Published:2008
Web of Science® Times Cited:15
Deposited By:Research Division
Deposited On:2011-07-15
Last Modified:2011-09-21

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