Climate change and increasing ocean acidity are already affecting marine life in the Southern Ocean. This has the potential to dramatically alter primary productivity, food chains, ecosystems and fisheries. Less sea ice, freshening ocean water and increasing acidity and temperature will cause substantial changes in the structure and dynamics of the marine food web.
Photo: Antarctic krill: Euphausia superba
ACE scientists are investigating the potential tipping points for ecosystem change in the Southern Ocean. This includes determining which key species will be more sensitive to climate change, which species may be critical for triggering change, whether changes will be different in different regions of Antarctica, and the possible effects on harvested populations such as krill and finfish, and species of high conservation value, such as whales. The relative importance of food web relationships and the possible changes to this food web if plankton and krill are affected by changes in the physical and biogeochemical environments in Eastern Antarctica will be investigated using existing data that link the physical, chemical and biological elements of the Southern Ocean ecosystem.
View: Dr So Kawaguchi discusses the importance of krill
View: Dr So Kawaguchi discusses research to understand impact of climate change on krill
Photo: Baleen Whale
Up to 25% of the total annual primary production in the sea ice zone of the Southern Ocean occurs as algae within the ice itself. ACE researchers are evaluating the relationship between algal growth and the physical properties of the ice in order to assess the impact on this productivity of changes in sea ice area or thickness. Historical datasets from ice cores and field measurements of sea ice algal biomass and production will be used to calibrate and validate models of sea ice primary productivity.
A second generation Antarctic marine ecosystem model will be developed to assess climate change impacts. A coupled ocean, ice, atmosphere and food web model for the Indian sector of the Southern Ocean will be developed based on the Regional Ocean Modelling System (ROMS). The model will be used to evaluate how the Southern Ocean food web might be altered by changes in the physical environment, and hence to assess the risk of climate change impacts on the ecosystem. Historical changes in Southern Ocean marine ecosystems, such as the impact to krill of the exploitation of seals, whales and finfish, will also be evaluated, and used to test the model.
New data from an ACE baseline ocean transect, together with existing data, will be used to evaluate the types of changes that could arise in phytoplankton and zooplankton communities as a result of climate change.
Projects and project leaders
- Risk Assessment of impacts on species: Dr Andrew Constable, Dr Martin Riddle
- Productivity of the Sea Ice Zone: Dr Andrew Constable, Dr Klaus Meiners
- Food Web Processes: Dr Andrew Constable, Dr Steve Nicol
- Changes and Uncertainties in Ecosystem Structure and Function: Dr Andrew Constable
View: Dr Andrew Constable talking about the Ecosystems Impacts Program