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Australian Minister for the Environment and Heritage
Senator the Hon. Ian Campbell
2 January 2006
Ocean currents, phytoplankton, krill, seabirds and whales will be measured, sampled, surveyed, counted and recorded in one of the largest marine science voyages of the Australian Antarctic programme, which sails today from Fremantle aboard Aurora Australis.
Australian Minister for the Environment and Heritage, Senator Ian Campbell, said the 10-week 'Baseline Research on Oceanography, Krill and the Environment - West' (BROKE-West) voyage will cover over one million square kilometres of the Southern Ocean.
It will travel adjacent to a rarely visited stretch of the Antarctic coastline, between 30° and 80° east, and in an oceanic region overseen by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR ).
Senator Campbell said BROKE-West would follow in the footsteps of a 1996 voyage, BROKE, which conducted similar studies in an adjacent CCAMLR sector.
"Together, the two voyages will cover one third of the Antarctic coastline and the majority of the Australian Antarctic Territory," Senator Campbell said.
Scientists from the Australian Antarctic Division and Antarctic Climate and Ecosystems Cooperative Research Centre will use the data to better understand the relationships between the physical environment and biological processes.
"The data analysis will allow scientists to better predict the effects of climate change and, in the case of krill, to establish accurate and sustainable catch limits," Senator Campbell said.
"The combined data from the two voyages will be vital for the development of improved climate models of the Southern Ocean and for fisheries management policy."
The voyage will include:
The Aurora Australis returns to Hobart on 14 March 2006.
Further details of the work to be carried out by scientists aboard the Aurora Australis is attached.
Renae Stoikos (Senator Campbell's office) 02 6277 7640 or 0418 568 434
Patti Lucas (Australian Antarctic Division) 0439 639 227
Recent observational studies suggest the population of minke whales in the Southern Ocean may have declined. However, visual counts of minke whales have led to varying population estimates. During BROKE-West, scientists will use passive acoustic technology to correlate suspected minke whale vocalizations with visual observations. The catch is that no-one knows what minke whales sound like.
Sonabuoys will be used to listen for unidentified sounds that could come from minke whales. Scientists will then determine if the sounds can be correlated with visual observations. The technique has proved successful with humpback, fin and blue whales. If minke vocalisations are recorded, the team could deploy passive acoustic devices under the sea ice, to monitor populations throughout the year. The acoustic devices will also provide the team with a snapshot of the other 'vocal' marine life in the survey region.
The oceanographic survey will estimate the flow of water through the region, and identify any sources of cold, dense bottom water (produced when sea ice forms), which drive ocean circulation patterns. This is important because ocean circulation patterns and water temperature are linked to other biological processes. In the 1996 BROKE voyage, for example, cold water welling up from below, was associated with higher densities of phytoplankton, krill, fish and whales.
The oceanographic team will use a CTD probe (conductivity, temperature, depth) to measure changes in conductivity (salinity), temperature and oxygen levels with depth, at regular intervals along transects between Fremantle and Antarctica. Water samples will also be analysed for changes in carbon dioxide (CO2) levels to determine whether the ocean is still absorbing CO2 and at what rate, and if there is a limit to how much it can absorb.
The ability of the Southern Ocean to take up CO2, and to sustain marine life such as krill, fish and whales, is dependent on the growth, abundance and distribution of microscopic marine plants or 'phytoplankton', as well as protozoa and bacteria.
During BROKE-West, marine biologists will collect and analyse water samples to determine the growth rate of these organisms, the photosynthetic rate of phytoplankton (and therefore the uptake of CO2 from the atmosphere), the grazing activity of protozoa (which eat phytoplankton and bacteria) and how many of these organisms there are. These studies will help to determine how much food is available to krill and, subsequently, higher predators. It will also enable scientists to gauge the CO2-absorbing capacity of this region of the Southern Ocean. Through microscopic examination, the team will also build a picture of the microbial communities in the region. Subsequent modelling of these communities will allow them to predict their responses to climate change.
An acoustic biomass survey of krill will be conducted to determine the sustainable catch limit for this CCAMLR region. The area was last surveyed in 1981 and a precautionary catch limit of 450,000 tonnes of krill per year was established. Since that time, however, there have been changes in technology, the environment and the fishery. There is evidence from other areas of the Antarctic that considerable changes have been occurring in the marine ecosystem over the last 30 years. As an expansion in the krill fishery is anticipated, it is prudent to ensure that catch limits in the area of Australia's national interest are based on the best scientific information available