Sea Ice Meltwater and Circumpolar Deep Water Drive Contrasting Productivity in Three Antarctic Polynyas
Moreau, Sebastien (University of Tasmania)
Lannuzel, Delphine (University of Tasmania)
Janssens, Julie (University of Tasmania)
Arroyo, Mar C. (Virginia Institute of Marine Science)
Corkill, Matthew (University of Tasmania)
Cougnon, Eva (University of Tasmania)
Genovese, Cristina (University of Tasmania)
Legresy, Benoit (University of Tasmania)
Lenton, Andrew (University of Tasmania)
Puigcorbé, Viena (Edith Cowan University)
Ratnarajah, Lavenia (University of Tasmania)
Rintoul, Stephen (University of Tasmania)
Roca Martí, Montserrat (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Rosenberg, Mark (University of Tasmania)
Shadwick, Elizabeth H. (Virginia Institute of Marine Science)
Silvano, Alessandro (University of Tasmania)
Strutton, Peter G. (University of Tasmania)
Tilbrook, Bronte (University of Tasmania)
Universitat Autònoma de Barcelona. Departament de Física

Date:	2019
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.
Note:	Unidad de excelencia María de Maeztu MdM-2015-0552
Rights:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Ice shelves ; Iron ; Phytoplankton biomass ; Polynyas ; Primary productivity ; Sea ice
Published in:	Journal of geophysical research. Oceans, Vol. 124, Issue 5 (May 2019) , p. 2943-2968, ISSN 2169-9291

DOI: 10.1029/2019JC015071

26 p, 7.0 MB

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Institut de Ciència i Tecnologia Ambientals (ICTA)
Articles > Research articles
Articles > Published articles