Prof Tom Trull
Antarctic Climate and Ecosystems CRC
Research voyage to the Southern Ocean to support maintenance of long term automated moorings for ocean monitoring and to study the biogeochemistry of sub-Antarctic waters.
This voyage will contribute to global datasets and increase understanding of Southern Ocean characteristics, variability and processes. The Southern Ocean Time Series (SOTS) moorings provide year-long observations in a critical part of the Southern Ocean, where ocean interactions are most intense and least studied. This information is vital for ongoing ocean and climate monitoring.
The voyage combines two primary projects:
- Southern Ocean Time Series (SOTS) (Prof Tom Trull, ACE CRC): Two new SOTS moorings will be deployed (SOFS-8 and SAZ-21) and two existing ones recovered (SOFS-7.5 and SAZ-20). An additional mooring (SOFS-6) will also be recovered for maintenance purposes. These automated deep-water moorings measure the exchanges of heat, water, carbon dioxide and oxygen between the ocean and atmosphere, and the physical and biological processes that control them.
- Sub-Antarctic biogeochemistry of carbon and iron, Southern Ocean Time Series site (Phillip Boyd, IMAS/UTas): Conduct ocean and atmospheric sampling to measure carbon and iron across a range of spatial scales at the SOTS sites. This data will help increase our understanding of how marine life and chemistry are controlled by both natural and man-made shifts in climate and ocean conditions.
The science team on this voyage includes 33 participants from six institutions, including four students.
As a result of this voyage, researchers have deployed moored platforms that collect data about the seasonal processes that control the productivity of the sub-Antarctic microbial foodweb. This information extends from the physics of ocean mixing and insolation, to the chemistry of ocean nutrients and the biological responses of phytoplankton, zooplankton and fish.
The voyage is part of a multiyear partnership between the Integrated Marine Observing System (IMOS) and MNF to deliver critical time-series ocean data from the Southern Ocean to global datasets. This data is crucial for use in ocean and climate science by the international research community.
A scientific highlight included a bloom of pyrosomes (Tunicata, Chordata) that was observed and collected on the in-situ pumps (ISPs). Due to their high abundance, they interfered with the Triaxus tows and CTD sensors. One night, many pyrosomes of the species Pyrosoma atlanticum were observed around the ship, many of them glowing due to bioluminescence. Little is known about the influence of pyrosomes on the sub-Antarctic carbon cycle or their biology, so this voyage was a unique opportunity to study their size distribution, cell structure and decomposition rate and collect samples for lipid and carbon measurements.