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Finding mesopelagic prey in a changing Southern Ocean

Citation

McMahon, CR and Hindell, MA and Charrassin, J-B and Corney, S and Guinet, C and Harcourt, R and Jonsen, I and Trebilco, R and Williams, G and Bestley, S, Finding mesopelagic prey in a changing Southern Ocean, Scientific Reports, 9, (1) Article 19013. ISSN 2045-2322 (2019) [Refereed Article]


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Copyright Statement

The Author(s) 2019. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) http://creativecommons.org/licenses/by/4.0/

DOI: doi:10.1038/s41598-019-55152-4

Abstract

Mesopelagic fish and squid occupy ocean depths extending below the photic zone and their vertical migrations represent a massive pathway moving energy and carbon through the water column. Their spatio-temporal distribution is however, difficult to map across remote regions particularly the vast Southern Ocean. This represents a key gap in understanding biogeochemical processes, marine ecosystem structure, and how changing ocean conditions will affect marine predators, which depend upon mesopelagic prey. We infer mesopelagic prey vertical distribution and relative abundance in the Indian sector of the Southern Ocean (20 to 130E) with a novel approach using predator-derived indices. Fourteen years of southern elephant seal tracking and dive data, from the open ocean between the Antarctic Polar Front and the southern Antarctic Circumpolar Current front, clearly show that the vertical distribution of mesopelagic prey is influenced by the physical hydrographic processes that structure their habitat. Mesopelagic prey have a more restricted vertical migration and higher relative abundance closer to the surface where Circumpolar Deep Water rises to shallower depths. Combining these observations with a future projection of Southern Ocean conditions we show that changes in the coupling of surface and deep waters will potentially redistribute mesopelagic prey. These changes are small overall, but show important spatial variability: prey will increase in relative abundance to the east of the Kerguelen Plateau but decrease to the west. The consequences for deep-diving specialists such as elephant seals and whales over this time scale will likely be minor, but the changes in mesoscale vertical energy flow have implications for predators that forage within the mesopelagic zone as well as the broader pelagic ecosystem.

Item Details

Item Type:Refereed Article
Keywords:Southern Ocean, Antarctic, marine predators, animal behaviour, climate prediction
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management of Antarctic and Sub-Antarctic Environments
UTAS Author:McMahon, CR (Dr Clive McMahon)
UTAS Author:Hindell, MA (Professor Mark Hindell)
UTAS Author:Corney, S (Dr Stuart Corney)
UTAS Author:Trebilco, R (Dr Rowan Trebilco)
UTAS Author:Williams, G (Associate Professor Guy Williams)
UTAS Author:Bestley, S (Dr Sophie Bestley)
ID Code:136429
Year Published:2019
Funding Support:Australian Research Council (DE180100828)
Deposited By:Ecology and Biodiversity
Deposited On:2019-12-19
Last Modified:2020-03-17
Downloads:0

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