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Estimating the average distribution of Antarctic krill Euphausia superba at the northern Antarctic Peninsula during austral summer and winter. Polar Biol 2022; 45:857-871. [PMID: 35673679 PMCID: PMC9165435 DOI: 10.1007/s00300-022-03039-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 11/03/2022]
Abstract
This study was performed to aid the management of the fishery for Antarctic krill Euphausia superba. Krill are an important component of the Antarctic marine ecosystem, providing a key food source for many marine predators. Additionally, krill are the target of the largest commercial fishery in the Southern Ocean, for which annual catches have been increasing and concentrating in recent years. The krill fishery is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which has endorsed a new management framework that requires information about the spatial distribution and biomass of krill. Here, we use krill density estimates from acoustic surveys and a GAMM framework to model habitat properties associated with high krill biomass during summer and winter in the northern Antarctic Peninsula region, an area important to the commercial fishery. Our models show elevated krill density associated with the shelf break, increased sea surface temperature, moderate chlorophyll-a concentration and increased salinity. During winter, our models show associations with shallow waters (< 1500 m) with low sea-ice concentration, medium sea-level anomaly and medium current speed. Our models predict temporal averages of the distribution and density of krill, which can be used to aid CCAMLR’s revised ecosystem approach to fisheries management. Our models have the potential to help in the spatial and temporal design of future acoustic surveys that would preclude the need for modelled extrapolations. We highlight that the ecosystem approach to fisheries management of krill critically depends upon such field observations at relevant spatial and temporal scales.
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Akhoudas CH, Sallée JB, Haumann FA, Meredith MP, Garabato AN, Reverdin G, Jullion L, Aloisi G, Benetti M, Leng MJ, Arrowsmith C. Ventilation of the abyss in the Atlantic sector of the Southern Ocean. Sci Rep 2021; 11:6760. [PMID: 33762612 PMCID: PMC7991437 DOI: 10.1038/s41598-021-86043-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 03/09/2021] [Indexed: 11/09/2022] Open
Abstract
The Atlantic sector of the Southern Ocean is the world's main production site of Antarctic Bottom Water, a water-mass that is ventilated at the ocean surface before sinking and entraining older water-masses-ultimately replenishing the abyssal global ocean. In recent decades, numerous attempts at estimating the rates of ventilation and overturning of Antarctic Bottom Water in this region have led to a strikingly broad range of results, with water transport-based calculations (8.4-9.7 Sv) yielding larger rates than tracer-based estimates (3.7-4.9 Sv). Here, we reconcile these conflicting views by integrating transport- and tracer-based estimates within a common analytical framework, in which bottom water formation processes are explicitly quantified. We show that the layer of Antarctic Bottom Water denser than 28.36 kg m[Formula: see text] [Formula: see text] is exported northward at a rate of 8.4 ± 0.7 Sv, composed of 4.5 ± 0.3 Sv of well-ventilated Dense Shelf Water, and 3.9 ± 0.5 Sv of old Circumpolar Deep Water entrained into cascading plumes. The majority, but not all, of the Dense Shelf Water (3.4 ± 0.6 Sv) is generated on the continental shelves of the Weddell Sea. Only 55% of AABW exported from the region is well ventilated and thus draws down heat and carbon into the deep ocean. Our findings unify traditionally contrasting views of Antarctic Bottom Water production in the Atlantic sector, and define a baseline, process-discerning target for its realistic representation in climate models.
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Affiliation(s)
- Camille Hayatte Akhoudas
- CNRS/IRD/MNHN Laboratoire d'Océanographie et du Climat-Expérimentations et Approches Numériques, Sorbonne Université, Paris, France.
| | - Jean-Baptiste Sallée
- CNRS/IRD/MNHN Laboratoire d'Océanographie et du Climat-Expérimentations et Approches Numériques, Sorbonne Université, Paris, France
| | - F Alexander Haumann
- Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, USA.,British Antarctic Survey, Cambridge, UK
| | | | - Alberto Naveira Garabato
- School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
| | - Gilles Reverdin
- CNRS/IRD/MNHN Laboratoire d'Océanographie et du Climat-Expérimentations et Approches Numériques, Sorbonne Université, Paris, France
| | - Loïc Jullion
- School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
| | - Giovanni Aloisi
- Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, Paris, France
| | - Marion Benetti
- Institute of Earth Sciences, University of Iceland, Reykjavik, Iceland
| | - Melanie J Leng
- NERC Isotope Geosciences Laboratory, British Geological Survey, Nottingham, UK.,Centre for Environmental Geochemistry, University of Nottingham, Nottingham, UK
| | - Carol Arrowsmith
- NERC Isotope Geosciences Laboratory, British Geological Survey, Nottingham, UK
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Baines PG, Condie S. Observations and Modelling of Antarctic Downslope Flows: A Review. OCEAN, ICE, AND ATMOSPHERE: INTERACTIONS AT THE ANTARCTIC CONTINENTAL MARGIN 2013. [DOI: 10.1029/ar075p0029] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Gordon AL. Western Weddell Sea Thermohaline Stratification. OCEAN, ICE, AND ATMOSPHERE: INTERACTIONS AT THE ANTARCTIC CONTINENTAL MARGIN 2013. [DOI: 10.1029/ar075p0215] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Fricker HA, Padman L. Thirty years of elevation change on Antarctic Peninsula ice shelves from multimission satellite radar altimetry. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc007126] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Nicholls KW. Water mass modification over the continental shelf north of Ronne Ice Shelf, Antarctica. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jc001713] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Timmermann R. Simulations of ice-ocean dynamics in the Weddell Sea 2. Interannual variability 1985–1993. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2000jc000742] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Fieg K, Gerdes R. Sensitivity of the thermohaline circulation to modern and glacial surface boundary conditions. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999jc000102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Tanaka K, Akitomo K. Baroclinic instability of density current along a sloping bottom and the associated transport process. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000jc000214] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fahrbach E, Harms S, Rohardt G, Schröder M, Woodgate RA. Flow of bottom water in the northwestern Weddell Sea. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000jc900142] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Padman L, Kottmeier C. High-frequency ice motion and divergence in the Weddell Sea. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999jc900267] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Beckmann A, Hellmer HH, Timmermann R. A numerical model of the Weddell Sea: Large-scale circulation and water mass distribution. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jc900194] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Haine TWN, Watson AJ, Liddicoat MI, Dickson RR. The flow of Antarctic bottom water to the southwest Indian Ocean estimated using CFCs. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jc02476] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Schauer U, Muench RD, Rudels B, Timokhov L. Impact of eastern Arctic shelf waters on the Nansen Basin intermediate layers. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96jc03366] [Citation(s) in RCA: 199] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Levine MD, Padman L, Muench RD, Morison JH. Internal waves and tides in the western Weddell Sea: Observations from Ice Station Weddell. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96jc03013] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Weppernig R, Schlosser P, Khatiwala S, Fairbanks RG. Isotope data from Ice Station Weddell: Implications for deep water formation in the Weddell Sea. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jc01895] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Vihma T, Launiainen J, Uotila J. Weddell Sea ice drift: Kinematics and wind forcing. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jc01441] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Robertson R, Padman L, Levine MD. Fine structure, microstructure, and vertical mixing processes in the upper ocean in the western Weddell Sea. ACTA ACUST UNITED AC 1995. [DOI: 10.1029/95jc01742] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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