Southern Ocean ecosystems

Two crabeater seals on the sea ice.
Sea ice provides important habitat for many Antarctic and Southern Ocean organisms including these crabeater seals. (Photo: Dave Allen, NIWA)

Southern Ocean ecosystems are threatened by:

  • global warming
  • ocean circulation changes
  • ocean acidification (due to increasing carbon dioxide from the atmosphere dissolving in the ocean)
  • sea ice retreat
  • invasive species
  • increased exploitation by humans.

Changes have been observed in the phytoplankton and zooplankton communities, with some species becoming more dominant; the movement of temperate species south and a contraction in the range of polar species; and changes in the ability of some organisms to form shells, due to ocean acidification. The current recovery of many higher predators (whales and seals) from historic over-exploitation will impose further change on Southern Ocean ecosystems.

In the future, a predicted reduction in sea ice will cause a loss of habitat for ice-associated organisms, from microbes to seals. It will also change the amount of light penetrating the ocean surface and surface water stratification (water layers of different salinity and temperature). These changes may reduce the extent of the ice edge algal bloom that is crucial to the productivity in the Southern Ocean and that supports the specialised food chain linked to krill.

Our research aims to:

  • identify the ecological responses and resilience of Southern Ocean ecosystems to the impacts of global change
  • develop cost-effective monitoring approaches to track the impacts of global change and the effectiveness of conservation measures on ecosystems.

The ability to detect and understand ecological changes in the Southern Ocean requires a carefully designed program of observations, experiments, monitoring and modelling. Existing initiatives include the CCAMLR Ecosystem Monitoring Program (CEMP), Australia’s Integrated Marine Observing System (IMOS), and the Southern Ocean Observing System (SOOS).

Products from our research will include ecosystem models that will inform conservation and management strategies in the Southern Ocean.