Map showing the oceanic sector in which the 2006 BROKE-West survey was conducted — known as CCAMLR Division 58.4.2.
In 2006 the BROKE-West survey covered a region of the Southern Ocean designated as CCAMLR Division 58.4.2 (orange sector) Photo: Peter Boyer, Steve Nicol

One of the most comprehensive ecosystem surveys ever conducted in the Southern Ocean is the focus of a special issue of Deep Sea Research Part II: Topical Studies in Oceanography published in May (Volume 57, Issues 9–10, May 2010).

The Baseline Research on Oceanography, Krill and the Environment-West (BROKE-West) survey, undertaken by Australian Antarctic program scientists in 2006, surveyed over 1.5 million km2 of ocean off the East Antarctic coast (between 30º and 80º east – orange sector on map). During the 10-week voyage, scientists examined everything from ocean circulation, temperature and chemistry, to microbial communities, phytoplankton, krill and fish, as well as whales and seabirds. The main focus, however, was on the distribution and abundance of Antarctic krill, to provide information to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) to help manage an expanding krill fishery (Australian Antarctic Magazine 8: 12, 2005).

The volume, edited by Steve Nicol of the Australian Antarctic Division and Klaus Meiners of the Antarctic Climate and Ecosystems Cooperative Research Centre, contains 20 scientific papers that detail the results of the survey. These include:

  • demonstrating that krill and their predators were abundant throughout the survey area;
  • observing an increase in temperature and salinity in bottom waters in the eastern sector of the study area;
  • identifying potential sources of Antarctic Bottom Water;
  • identifying pathways of carbon dioxide uptake and release by the ocean;
  • observing algal blooms under the sea ice and near the ice edge that are controlled by iron concentrations.

The special volume of the journal contains the first analysis of the data the scientists collected. The next step will be to create a single dataset that combines the results from the geographically adjacent BROKE (1996 survey — yellow sector on map) and BROKE-West surveys, to produce an overview of the ecosystems off the entire coastline of East Antarctica. There are few such comprehensive datasets for the Southern Ocean so these voyages will leave a legacy that will, hopefully, be the object of study for many years to come.

on