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Sea ice meltwater and circumpolar deep water drive contrasting productivity in three Antarctic polynyas

Citation

Moreau, S and Lannuzel, D and Janssens, J and Arroyo, MC and Corkill, M and Cougnon, E and Genovese, C and Legresy, B and Lenton, A and Puigcorbe, V and Ratnarajah, L and Rintoul, S and Roca-Marti, M and Rosenberg, M and Shadwick, EH and Silvano, A and Strutton, PG and Tilbrook, B, Sea ice meltwater and circumpolar deep water drive contrasting productivity in three Antarctic polynyas, Journal of Geophysical Research: Oceans, 124, (5) pp. 2943-2968. ISSN 2169-9275 (2019) [Refereed Article]


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Copyright 2019 American Geophysical Union.

DOI: doi:10.1029/2019JC015071

Abstract

In the Southern Ocean, polynyas exhibit enhanced rates of primary productivity and represent large seasonal sinks for atmospheric CO2. Three contrasting east Antarctic polynyas were visited in late December to early January 2017: the Dalton, Mertz, and Ninnis polynyas. In the Mertz and Ninnis polynyas, phytoplankton biomass (average of 322 and 354 mg chlorophyll a (Chl a)/m2, respectively) and net community production (5.3 and 4.6 mol C/m2, respectively) were approximately 3 times those measured in the Dalton polynya (average of 122 mg Chl a/m2 and 1.8 mol C/m2). Phytoplankton communities also differed between the polynyas. Diatoms were thriving in the Mertz and Ninnis polynyas but not in the Dalton polynya, where Phaeocystis antarctica dominated. These strong regional differences were explored using physiological, biological, and physical parameters. The most likely drivers of the observed higher productivity in the Mertz and Ninnis were the relatively shallow inflow of iron‐rich modified Circumpolar Deep Water onto the shelf as well as a very large sea ice meltwater contribution. The productivity contrast between the three polynyas could not be explained by (1) the input of glacial meltwater, (2) the presence of Ice Shelf Water, or (3) stratification of the mixed layer. Our results show that physical drivers regulate the productivity of polynyas, suggesting that the response of biological productivity and carbon export to future change will vary among polynyas.

Item Details

Item Type:Refereed Article
Keywords:sea ice, polynya, productivity, water masses
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Change Adaptation Measures
UTAS Author:Moreau, S (Dr Sebastien Moreau)
UTAS Author:Lannuzel, D (Associate Professor Delphine Lannuzel)
UTAS Author:Janssens, J (Miss Julie Janssens)
UTAS Author:Corkill, M (Mr Matthew Corkill)
UTAS Author:Cougnon, E (Dr Eva Cougnon)
UTAS Author:Genovese, C (Miss Cristina Genovese)
UTAS Author:Legresy, B (Dr Benoit Legresy)
UTAS Author:Lenton, A (Dr Andrew Lenton)
UTAS Author:Ratnarajah, L (Miss Lavenia Ratnarajah)
UTAS Author:Rintoul, S (Dr Steve Rintoul)
UTAS Author:Rosenberg, M (Mr Mark Rosenberg)
UTAS Author:Silvano, A (Mr Alessandro Silvano)
UTAS Author:Strutton, PG (Associate Professor Peter Strutton)
UTAS Author:Tilbrook, B (Dr Bronte Tilbrook)
ID Code:132997
Year Published:2019
Web of Science® Times Cited:1
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2019-05-30
Last Modified:2019-09-05
Downloads:0

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