NIWA ship returns from Antarctica with ‘pieces of a puzzle’

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The absence of sea ice near Antarctica over the past six weeks has astonished scientists undertaking research aboard NIWA’s flagship research vessel Tangaroa.

Free of sea-ice - panoramic view of the Antarctic Continent, including Cape Adare and Cape McCormick.

David Bowden, NIWA

Tangaroa returned to port in Wellington this morning following a six-week multi-disciplinary scientific voyage studying ocean, atmosphere, and ecosystem processes in the Southern Ocean. The science team on board included researchers from NIWA, Auckland University, the University of Canterbury, and the Korean Polar Research Institute.

R/V Tangaroa returned to Wellington mid-morning Wednesday 21 March 2018. [Photo: Dave Allen, NIWA]

Voyage leader and NIWA marine ecologist Dr David Bowden said despite having lost three days to bad weather, the highlight of the voyage was “achieving so much of what we set out to do”.

“We have installed long term experiments and collected a wide range of samples and data that will help to improve understanding of climate and oceanographic processes in the region, and how these influence the marine ecosystem.”

However, Dr Bowden said the 23 scientists and 17 crew on board were all surprised by the lack of sea ice.

“We planned this voyage knowing it was late in the season and that we might not be able to get where we wanted to go because of ice, but it has been almost completely ice-free.”

Sea ice forms when the ocean surrounding Antarctica freezes. It plays a crucial role in the global climate system but this summer coverage has dropped to its second-lowest on record.

“It has been an extraordinary year from that aspect but has allowed us to go to places we thought would probably be inaccessible.”

Data gathered during the voyage will be valuable in helping to determine the effects a lack of sea ice has on the Antarctic ecosystem.

“We are bringing back pieces of a complex jigsaw puzzle.

“We have studied many aspects of the ecosystem, from microbial production in the plankton to the distributions of seabed fauna, krill, and whales. But it’s only when we have analysed these data in the context of what we know from other years and other regions that we will be able say what the ecological impacts of decreasing sea ice might be,” Dr Bowden said.

The voyage had several scientific objectives aimed at better understanding:

  • Climate change effects on oceanographic processes
  • Marine microbial community structure and function
  • Influence of marine aerosols on cloud formation and properties of Antarctic clouds
  • Seabed habitats and fauna inside and outside the Ross Sea Marine Protected Area (MPA)
  • The role of whales in the Antarctic ecosystem
  • The abundance, diversity, and distribution of mesopelagic fish, krill and zooplankton.

One of the key objectives is to generate baseline data required to determine whether the objectives of the Ross Sea MPA are being achieved. The MPA covers more than 1.55 million square kilometres and came into existence in December.

Dr Bowden said while the voyage was very successful overall, the primary objective was to establish the Ross Outflow Experiment off Cape Adare and completing this phase of the voyage was a major achievement.

“The experiment will yield important data about long-term changes in the amount of extremely cold, dense water that flows out from the Ross Sea and influences the global circulation of the oceans.”

Tangaroa will return to Antarctica in a year’s time to carry our further research and pick up a total of seven instrument moorings deployed on this voyage. Some of the moorings carry arrays of instruments that record salinity, temperature and currents at different depths, while others record the presence of whales or krill.

“The other side to this year’s success, of course, is that if sea ice cover returns to a more normal extent next year it might well be a more difficult proposition to retrieve the moorings than it was to deploy them,” Dr Bowden said.

Contact:

Dr David Bowden, NIWA marine ecologist
Ph 04 386-0914
Mob 021 121-9312

Research subject: Antarctica