Mooring deployment from the RV Laura Bassi. One of our goals for this voyage is a substantial increase in our year-round environmental data acquisition through deployment of autonomous sampling devices at key locations across the Ross Sea. Photo: Lana Young.
Ross Sea Voyage Update #8: Along the continental shelf break
Currently we’re bashing through sea ice to get to a clear patch of water near Cape Hallett, where we hope to be out of the coming wind and waves.
Celebrating wāhine
Today is International Day of Women and Girls in Science – a UNESCO initiative designed to promote full and equal access to and participation in science for women and girls. Our Aotearoa New Zealand research team is 75% women, many of whom put a lot of effort into communicating the value of science, alongside conducting excellent research. Our wāhine team photo, taken on the helicopter deck, included videographer Lana Young is aboard as our voyage storyteller, so we can show Kiwis what science on the Southern Ocean looks like. Sharing this journey is part of our mission - New Zealand will be impacted by the effects of change in Antarctica and the Southern Ocean – through changing weather, changing oceans and melting ice.
The New Zealand team on board consists of nine women, out of a team of 12. Christina Riesselman not shown here as she returned to NZ after Leg 1 of the voyage. Photo: Craig Stewart.
New Zealand glider recovery
Having departed for the Ross Sea continental shelf, our first task was recovery of the ocean Glider, Manaia. It had been operating for five days in the narrow continental shelf region on a short, but risky, mission.
There was some concern, as our pick-up of the glider had been delayed by weather, and in the meantime a decent-sized patch of sea ice was moving over the glider working area. Glider leader, Jasmin McInerney, was in regular communications with NIWA’s NewZealand-based glider pilot team, Eleanor Haig and Cassandra Elmer. While the gliders need 24/7 monitoring, there are large chunks of time when there are no communications, so it’s not intensive unless there’s an issue or during the pre-recovery phase.
The glider recovery had us looking very hard at several ice products, in conjunction with the bridge crew. The trade-off in this situation is that we can keep the glider from surfacing for a long period to avoid ice, but then we can’t talk to it.
Through a combination of skill and luck, the glider surfaced 150m south of a very messy patch of sea ice. Manaia was quickly recovered and maintenance and downloading commenced, and 180 multi-parameter profiles were extracted. Excitingly, our early look at the data suggests the glider did dip down into warmer waters right near the shelf-break edge.
A glider deployment. Photo: Lana Young.
Deploying Argo floats
From the glider pickup, we turned nor-west to run along the shelf break. Partway along the transit to Iselin Bank, we deployed three Argo profiling floats – the last for the trip.
The Iselin Bank disrupts the line of the Ross continental shelf. It’s a location with strong tidal flows and is critical in terms of ice shelf stability, ocean circulation and biological productivity. The three Argo deployments were designed to help with the understanding of the Antarctic slope current – this is a coherent circulation feature that rings the Antarctic continental shelf and regulates the flow of water toward the Antarctic coastline. In particular, we’re hoping this deployment will aid in understanding how Iselin Bank might disrupt the current, or not.
This deployment made it a total of eleven new Argo float deployments for the voyage, with two existing Italian floats also picked up and redeployed in more strategic locations. NIWA’s Dr Denise Fernandez has spent some time developing a structure for how shared robotic sensors, augmented by traditional moorings, could provide a consistent observation network for the Ross region. These robotic sensor packages are normally deployed off the continental shelf. However, with ice detection and other enhancements, the community is deploying more units on continental shelves.
The 11 new Argo floats roughly doubles the profilers on the Ross continental shelf. Most of these are the basic temperature and salinity, but there are a growing number of units with added sensors, including oxygen and other biologically relevant parameters. The approach has some challenges of course; the sampling is not in one location and the position needs to be inferred during winter ice cover. Despite these limitations, this is a game changer for data in the region.
We were grateful that, thanks to the Antarctic Science Platform and Denise’s liaison activities, Canadian and United Kingdom colleagues provided floats for us to deploy, as part of collaborative ocean research. As the data are immediately open, the whole community benefits. More float deployments are planned for next year, by both Italy and New Zealand.
Last year urgent expansion of Southern Ocean science in the emerging climate crisis. 300 scientists from 25 nations met in the Antarctic gateway city of Hobart for the first-ever international conference of the Southern Ocean Observing System (SOOS). A joint statement was released at the close of the conference, saying that no nation alone can provide the research needed to address the climate questions facing us. One of our goals for this voyage is a substantial increase in our year-round environmental data acquisition through deployment of autonomous sampling devices at key locations across the Ross Sea. It means a lot to us here on the ship that our international community turned up for us and provided kit - thank you to the British Antarctic Survey and Fisheries and Oceans Canada.
Float deployment from the RV Laura Bassi. Photo: Lana Young.
CTD profile sampling
An example of the many science activities that relied on the CTD along this transit line was the microplastics sampling of University of Waikato PhD student Georgia Pollard. She is gathering targeted water samples from specific depths. The method involves careful calibration of the sampling equipment and will potentially add to the growing pool of evidence for the spread of plastics to the extremities of the Earth system. These data will provide a contextual adjunct to the zooplankton data that Georgia is working on with NIWA’s Dr Svenja Halfter.
PhD student Alina Madita Wieczorek collecting water samples from the CTD rosette. Photo: Lana Young.
PhD student Svenja Halfter deploying bongo nets to sample the organisms that live in the water column. Photo: Lana Young.
Emergency glider pick-up
One vulnerability for the voyage structure was having a number of gliders far from the vessel that might need to be picked up at short notice. This came to pass during the Iselin Bank work, which had to be cut short while we headed south-west to recover the two Italian gliders, one of which was running low on batteries due to the cold. Fortunately, the gliders were both recovered efficiently after a 15-hour steam. With the multi glider dataset, we now get to workshop multi-glider synthesis ideas while we hide from the next weather frontal system.
Mooring B
From the emergency glider pickup point, we headed north to one of the key Italian hydrographic moorings – Mooring B. This is one of a number of instrumented moorings that have been maintained by Italy for more than a decade and their value is becoming increasingly apparent as ocean science in the area focuses on salinity and oxygen changes. The Italian team was able to recover and redeploy in the face of deteriorating weather.
After the mooring operations, the New Zealand team conducted a 3am CTD profile sampling for microplastics, sediment, eDNA and water column structure before making the 14-hour run to the relative shelter of the Victoria Land coast as 40 knot winds from the south set in.
Working in 24-hour sunshine is sometimes an advantage. Because our research contingent is small, and spread over a number of disciplines, we are not able to run fixed shifts, so we’re monitoring workloads and making sure people are as rested as possible. The two-day weather enforced rest will be well deserved.
This update was sent from the ship by New Zealand voyage leader Prof Craig Stevens and revised by the New Zealand-based communications team.