RV Tangaroa in Antarctica, 2023. Photo: NIWA
Highlights from ecosystems research 2022/23
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.
Our team of researchers in the Ross Sea Ecosystems project is working to better understand what the future may hold for these environments. We are developing new techniques and autonomous instruments for remote sensing to fill gaps in understanding of biodiversity and ecological process.
Some research highlights from the past year:
Research Voyage to the Ross Sea
A major focus of fieldwork during 2022-23 was the 2023 research voyage to the Ross Sea and Victoria Land coastline. The aim was to increase knowledge of coastal marine biodiversity and key environmental and biological processes, and thereby improve understanding of ecosystem function and likely responses to future change. Over 20,000 samples were taken and over 14,000 m2 of sea floor was imaged. Ongoing observations of environmental state across multiple trophic levels supports scientific evaluation of the ecological status, spatial adequacy, and effectiveness of the Ross Sea region Marine Protected Area.
Fast ice fieldwork
A fast-ice-based field campaign was carried out around Ross Island and the southern Victoria Land coasts, which successfully retrieved two environmental instrument arrays deployed in 2021/22, redeployed one instrument array, and surveyed three new locations. The instrument arrays logged an entire year of data, providing location-specific information on temperature, circulation, and light.
Lake Benthic Communities
Fieldwork was undertaken at Lake Fryxell in collaboration with USAP researchers, focussing on understanding how perennially ice-covered lakes are responding to changing climate. In addition to supporting long term experiments addressing turnover of benthic microbial communities in response to lake level rise, new observations on lake ice have shown how current conditions result in ice now thinner than previously recorded and consequently transmits more light. Unexpected consequences for microbial mat communities are an increase in photosynthesis, resulting in ebullition of gases within the mats, and leading to changes to buoyancy and loss of biomass to the lake ice above.
Sampling at Lake Fryxell, 2022/23. Photo: Anthony Powell
eDNA monitoring
A new method showed the potential of eDNA monitoring using bycatch marine sponges. eDNA signal strength correlated strongly with fish catch abundance, suggesting that species abundance may be estimated from eDNA surveys. eDNA signals revealed a spatial pattern resembling the in-field community assemblages and largely concur with community structures obtained from known distribution patterns. Additional aquatic eDNA and sponge samples were collected during the 2022/23 field season.
A novel primer set targeting the 16S rRNA gene has been developed for Southern Ocean cephalopods to facilitate cephalopod eDNA monitoring in the Ross Sea. A primer set for Southern Ocean echinoderms is next to be developed. To aid in the design of primers and help interpret eDNA data, a new software is in the final stages of development.
Examples of Antarctic sponges (clockwise from top left) Mycale acerate (Tera Nova Bay) Sphaerotylus antarcticus. Photo: Ian Hawes
Automatic weather station network
Fieldwork occurred in Miers Valley, Taylor Valley, and Botany Bay as part of the annual automatic weather station (AWS) network maintenance and data collection. A new high-elevation AWS was installed at Cape Christie to extend our long-term monitoring to the northern sections of the eastern Ross Sea coastline. We also characterised the spatial variation of surface temperature in Taylor Valley using a newly developed helicopter-mounted aerial survey IR camera system.
Synthesis of biogeographical knowledge
The work to retrieve and synthesize biogeographical knowledge from literature using machine learning has advanced. More than 5,000 PDFs have been fully annotated. We have represented the biogeographical data in a spatially explicit and statistics-based framework.
Terrestrial sentinel sites
We are working to harmonise the sampling approach for terrestrial sentinel sites with the National Ecological Observation Network (NEON) philosophies. Importantly, NEON has set the gold standards for a wide range of environmental and ecological measurements, which can inform future monitoring efforts once the sentinel sites are established.
Seafloor productivity
Footage from Ross Sea research voyages identified the flora, fauna, and seafloor habitats encountered along deep-towed imaging system (DTIS) transects and generated counts of taxa, taxa groups, and seafloor substrates at different locations, sites, and depths. Methods were trialled to analyse higher-resolution still images. We continue to explore the potential for hyperspectral imaging techniques in characterising seafloor productivity.
The seafloor off Cape Wheatstone, with diverse marine life at ~50 metres. Photo: NIWA
Phytoplankton
Phytoplankton biomass, composition, and productivity were characterised during the RV Tangaroa 2023 voyage, providing complimentary datasets to previous voyages. This is enabling identification of the key environmental drivers of different phytoplankton groups, underpinning model development of trophic structure and food webs. Sample collection for dissolved iron, which is a critical limiting nutrient of primary productivity in this region, took place with an increased focus on sources in the Ross Sea. This benefited from collaboration with an ASP Opportunity Fund project on subglacial discharge in coastal waters and the collection of ice samples, which will determine their respective significance in terms of iron to supply to Ross Sea shelf waters.
Zooplankton method development
The Continuous Plankton Recorder was deployed on all long transects during the RV Tangaroa 2023 voyage, trialling a new preservative as part of the work towards developing a genetic analysis method for zooplankton. Oblique net hauls with the Bongo net were also carried out to gather samples of zooplankton from deeper depths and with no preservative. In parallel, research has continued to develop universal primers for genetic analysis of zooplanktonic material, and a Southern Ocean species reference database has been developed. We are also testing a DNA fingerprinting analysis to determine whether a sequencing-independent method is feasible.
Hauwai-20
The Hauwai-20 continues to be developed. The past year has focussed on overcoming challenges (e.g. hardware-software interfaces to control the complex robotic commands), as well as operational pressure testing, winch integration, whole assembly, and pool testing. First deployment in Antarctica will be in the 24/25 field season.
Sea ice ecology
The first systematic sampling trial of the sympagic sampler was successfully deployed to collect cores of platelet ice and associated water and organisms. The new method allows scientists to investigate ice-associated organisms both within a single core, ranging from sea ice core bottom down to platelet ice-water interface, as well as between sites on a larger scale. The new methodology and data will allow us to relate primary production and metazoan grazing in sympagic systems to environmental parameters.
The mobile drilling operation for quantitative coring of the sub-ice platelet layer. Photo: Natalie Robinson