Under the sea ice

Under the sea ice. Photo: Jana Newman

Highlights from ecosystems’ research 2021/22

29 July 2022

The Ross Sea region contains one of the most productive marine ecosystems in the Southern Ocean, encompassing open ocean, pack ice and coastal habitats, including much of the world’s largest marine protected area.

It also harbours diverse land-based ecosystems ranging from iconic Antarctic lakes to ancient soils that are home to unique biota.

The Antarctic Science Platform’s Project 3 - Projecting Ross Sea Ecosystem Changes in a Warming World is working to better understand what the future may hold for these environments, with a team of researchers looking at:

  • How can we expect the distribution of organisms to change in a +2°C world?
  • How vulnerable are food webs to changes in ice dynamics and ocean and atmospheric circulations?
  • What are the consequences of these changes for ecosystem integrity?

The programme undertakes sea ice, ocean and land-based research, and includes developing new techniques and autonomous instruments for remote sensing – there are many gaps to fill in our understanding of biodiversity and ecological process. This new knowledge, feeds into mapping of biodiversity and modelling how this may change as the world warms.

K882 Probe Deployment

The team prepares the probe for deployment in their containerised camp on Ross Ice Shelf. Photo: Anthony Powell

2021/22 saw significant fieldwork and sampling undertaken. Seafloor communities were the focus of a team working in McMurdo Sound and at Granite Harbour to better understand how benthic (seafloor) organisms will respond to a changing climate.

A key achievement of the fieldwork was the use of underwater drones for transect sampling, providing access to a depth range of 10-100m, going beyond what is possible for dive teams. The team collected seafloor invertebrates, microalgae and fish from a range of new locations, and successfully deployed three new instrument arrays at Granite Harbour, which will remain in place for one year, providing a long-term picture of coastal environmental conditions.

An ongoing collaboration between the Platform and the Korean Polar Research Institute (KOPRI) facilitates cross-site comparisons. Samples of a core set of sponges, bivalves and echinoderms, all common across the Ross Sea Region, are being made in McMurdo Sound and from the Korean station, Jang Bogo Station, in Terra Nova Bay.

In a collaboration with Project 4, new technology designed to sample the sub-ice platelet layer was tested for the first time in McMurdo Sound. The sub-ice platelet layer consists of an accumulation of disc-shaped ice crystals on the underside of sea ice, originating from supercooled water generated by basal melting of ice shelves. The layer is a significant component of Antarctic marine ecosystems, providing habitat for sea ice algae and a protective environment for the egg and larval stages of fish species, including Antarctic silverfish.

The custom-made drilling and sampling system successfully retrieved intact cores, promising to allow researchers to investigate the physical properties of the sub-ice platelet layer and its associated biology.

Scientists collecting platelet ice samples from under the sea ice which is a habitat for marine organisms Photo Brett Grant

Scientists collecting platelet ice samples from under the sea ice which is a habitat for marine organisms. Photo: Brett Grant

A combination of remotely operated vehicle (ROV), underwater experimentation and sampling techniques was used to study microbial mats at multiple inland lakes and ponds in the Taylor and Wright Valleys. These mats form a significant component of the aquatic ecosystem, but are particularly vulnerable to the effects of climate change. Information from the research will inform management strategies for the McMurdo Dry Valleys, designed to reduce additional stress caused by human activity.

The network of automatic weather stations in the Dry Valleys was expanded, which will improve our ability to model present and future regional climates.

At the bottom of Lake Bonney, Dry Valleys

At the bottom of Lake Bonney, Dry Valleys

Off the ice, an autonomous underwater biosampler is in the final stages of being built and tested. This will be deployed in 2023 and allow year-round sampling under sea ice.

Post-field analyses in New Zealand over the past year has included molecular approaches (genomic, eDNA, metabarcoding), chemical (isotope and trace elements), environmental data and biological surveys. Genetic identification of zooplankton is a key step to understanding and modelling the Ross Sea pelagic (ocean) foodweb. Genetic fingerprinting of these animals will help us to understand how connected the populations are, giving us an idea of the ability of organism to move across long distances as planktonic larvae. Comparisons of carbon, nitrogen and sulphur isotopes in their tissues provide information on differences in primary food sources and food chain structure in these different settings.

Environmental and biological data, and remote sensing data, is being incorporated into modelling through collaboration with the National Modelling Hub, so forecasts of future environmental conditions under a range of emissions scenarios can be assessed.