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Global drivers on Southern Ocean ecosystems: changing physical environments and anthropogenic pressures in an earth system

Citation

Morley, SA and Abele, D and Barnes, DKA and Cardenas, CA and Cotte, C and Gutt, J and Henley, SF and Hofer, J and Hughes, KA and Martin, SM and Moffat, C and Raphael, M and Stammerjohn, SE and Suckling, CC and Tulloch, VJD and Waller, CL and Constable, AJ, Global drivers on Southern Ocean ecosystems: changing physical environments and anthropogenic pressures in an earth system, Frontiers in Marine Science, 7 Article 547188. ISSN 2296-7745 (2020) [Refereed Article]


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DOI: doi:10.3389/fmars.2020.547188

Abstract

The manuscript assesses the current and expected future global drivers of Southern Ocean (SO) ecosystems. Atmospheric ozone depletion over the Antarctic since the 1970s, has been a key driver, resulting in springtime cooling of the stratosphere and intensification of the polar vortex, increasing the frequency of positive phases of the Southern Annular Mode (SAM). This increases warm air-flow over the East Pacific sector (Western Antarctic Peninsula) and cold air flow over the West Pacific sector. SAM as well as El Nino Southern Oscillation events also affect the Amundsen Sea Low leading to either positive or negative sea ice anomalies in the west and east Pacific sectors, respectively. The strengthening of westerly winds is also linked to shoaling of deep warmer water onto the continental shelves, particularly in the East Pacific and Atlantic sectors. Air and ocean warming has led to changes in the cryosphere, with glacial and ice sheet melting in both sectors, opening up new ice free areas to biological productivity, but increasing seafloor disturbance by icebergs. The increased melting is correlated with a salinity decrease particularly in the surface 100 m. Such processes could increase the availability of iron, which is currently limiting primary production over much of the SO. Increasing CO2 is one of the most important SO anthropogenic drivers and is likely to affect marine ecosystems in the coming decades. While levels of many pollutants are lower than elsewhere, persistent organic pollutants (POPs) and plastics have been detected in the SO, with concentrations likely enhanced by migratory species. With increased marine traffic and weakening of ocean barriers the risk of the establishment of non-indigenous species is increased. The continued recovery of the ozone hole creates uncertainty over the reversal in sea ice trends, especially in the light of the abrupt transition from record high to record low Antarctic sea ice extent since spring 2016. The current rate of change in physical and anthropogenic drivers is certain to impact the Marine Ecosystem Assessment of the Southern Ocean (MEASO) region in the near future and will have a wide range of impacts across the marine ecosystem.

Item Details

Item Type:Refereed Article
Keywords:Southern Annular Mode, ozone hole, cryosphere and climate change, biogeochemsitry, carbon dioxide, non-indigenous species, warming, freshening
Research Division:Earth Sciences
Research Group:Climate change science
Research Field:Climate change processes
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Constable, AJ (Dr Andrew Constable)
ID Code:150477
Year Published:2020
Web of Science® Times Cited:26
Deposited By:Australian Antarctic Program Partnership
Deposited On:2022-06-16
Last Modified:2022-06-16
Downloads:0

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