SOTS: automated moorings for climate and carbon cycle studies in the Southern Ocean

Voyage Number

IN2018_V02

Voyage Dates

01 Mar, 2018 to 20 Mar, 2018

Voyage Location

Hobart to Hobart

Chief Scientist

Prof Tom Trull

Institution

Antarctic Climate and Ecosystems CRC

View the full voyage

Voyage summary

Research voyage to 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 is information vital for informing ocean and climate monitoring.

The voyage combines two primary projects:

1. Southern Ocean Time Series (SOTS) (Prof Tom Trull, ACE CRC): Two new SOTS moorings will be deployed and two existing ones recovered. These automated deep-water moorings will measure the exchanges of heat, water, carbon dioxide and oxygen between the ocean and atmosphere, and the physical and biological processes that control them.
2. Subantarctic biogeochemistry of carbon and iron, Southern Ocean Time Series site (Phillip Boyd, IMAS/UTas): Conduct underway ocean and atmospheric sampling to measure carbon and iron across a range of spatial scales. 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 voyage includes one piggyback project:

• Bio-acoustic and trawl surveys of micronekton (Dr Rudy Kloser, CSIRO): Project to increase our understanding of the diversity, distribution, biomass and energetic needs of micronekton to further understanding the carbon cycle and linking primary production to top predators.

Voyage outcomes

As a result of this voyage, researchers have deployed automated moored platforms that assemble an integrated view of the seasonal processes that control the productivity of the sub-Antarctic microbial foodweb.  This analysis extends from the physics of ocean mixing and insolation, to the chemistry of ocean nutrients and the biological responses of phytoplankton, zooplankton and fish.

Micronekton sampling identified fishes, crustaceans, cephalopods and gelatinous zooplankton. The two most abundant fish species in trawl sampling were Lampanyctus australis (relatively large-bodied but juveniles also recorded) and Electrona carlsbergi (relatively small-bodied).

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.