2024 02 19 ASP team on Helo deck Lana Young

Photo: Lana Young

Ross Sea Voyage Update #12: Crossing the Antarctic Circumpolar Current

1 March 2024

James Clark Ross’s voyage came through the Ross Sea region on his voyage of discovery in the early 1840s. It has been suggested that this is around the time that the first signatures of human-induced climate change were being imprinted on the planet. The waters they were sailing through are only perhaps a quarter of the way through the global thermohaline circulation journey. At similar scales, the ocean changes occurring in this region today will head north to irrevocably change the planet.

2024 02 12 cape hallett emerging from fog Craig Stevens

Cape Hallett emerging from the fog. Photo: Craig Stevens

The journey home

We are heading north too. After finishing our last Antarctic sampling, we picked a line through patches of Southern Ocean storm activity. The medium range weather forecasts gave us a good sense of what was coming up, and a path was identified with minimum waves.

The dominant circulation feature in the Southern Ocean is the Antarctic Circumpolar Current (ACC) which flows clockwise (as seen from the South Pole) from west to east around Antarctica. Crossing the ACC was suitably uncomfortable but could have been far worse – it was only about a 24-hour period where it was too difficult to do anything but hold on. Unfortunately, the weather was not sufficiently gentle for us to do some planned acoustics-eDNA sampling.

However, NIWA’s Dr Svenja Halfter was able to sample all the way through the ACC with her Continuous Plankton Recorder. The heavy “tow-fish” is towed behind the ship and a form of gauze bandage is slowly spooled out, acting as a time-evolving filter. This collector is later analysed for species identification. This is an old-school but effective way of sampling plankton. This method has twin advantages: (i) it is such an old method, it can be compared with huge databank of prior samples, and (ii) it’s able to be conducted in almost the worst of weather.

Similarly, Matthias Dehling from Monash University kept up his ecological observer work and is looking set to hold the record for recording the first and the last data for the voyage. Most recently he’s seen the exciting transition from the Polar Front region, to where seabirds of the sub-Antarctic islands start to dominate. He was even starting to complain it was getting too warm standing around on his observation platform!

We can now see the coast of Te Waipounamu (New Zealand’s South Island) off our port bow as we are swept north on the Southland Current towards Lyttelton. It’s a reminder of the connectedness of the oceans and its central role in climate.

2024 01 22 midnight sun Craig Stevens

Midnight sun. Photo: Craig Stevens.

2024 01 30 RI Spengiuns adelie Lana

Adélie penguins in front of the Ross Ice Shelf. Photo: Lana Young.

Many thanks (molte grazie)

Thanks to so many people and agencies for their support of this Ross Sea voyage – it’s a long list!

Ian Hawes and Nancy Bertler from the Antarctic Science Platform identified the opportunity, set the process in train and then kept everything on track. Franco Coren with the vessel operator OGS, Captain Franco Sedmak, and crew aboard the RV Laura Bassi worked hard to make us feel operationally welcome. At the heart of it all, our Italian colleagues - especially PNRA Principal Investigators (PIs) Pierpaolo Falco, Paola Rivaro and Pasquale Castagno - welcomed us as equals, were open with their technicians and data, and sought to build collaborations and links.

So much collaborative thinking will stem from this voyage, and not only at the PI level, but also the early career researcher (ECR) community. MAC3 Impact Philanthropies made that possible and inspired the whole team with ideas well beyond the voyage. It’s a genuinely unique feature of the voyage and ECR-led ideas are very timely for the future of science.

Deb Diaz, Mel Climo, Jenevieve Peacock (Antarctica NZ/Antarctic Science Platform) and Ryan Willoughby (NIWA) kept the communication channels operating. Peter McComb, Kevin MacKay, Gavin Macaulay, Kavid Pasad, Alice Overend and Cassandra Elmer set us up, even though it was right around the end-of-year break. Eleanor Haigh and Cassandra Elmer piloted the glider from shore at all hours.

Port-side, Bruce King (Lyttelton Shipping & Marine Agencies), Paul ‘Woody’ Woodgate (Antarctica New Zealand) and Bob Dagg (University of Otago) got us on and off the ship – Christchurch really is an Antarctic Gateway City.

The mid-voyage team swap-in was an action movie on its own. The staff at Scott Base and Mario Zuchelli Station, as well as the New Zealand Defence Force, the pilots and crew from the bases, all looked after our team. Starboard Maritime Intelligence assisted with the position data, and look to the Southern Ocean Observing System (SOOS) sometime soon for the first data generated as a result of our voyage.

Lastly, and not least, the New Zealand science team were amazing. This trip was set up on very short time frames and involved significant challenges. The team, a mix of experience-levels and perspectives, worked so hard and for so long. We should all be very proud of them. Thanks Meghan Duffy, Luisa Fontanot, Christina Riesselman, Georgia Pollard, Craig Stewart, Lana Young, Matthias Dehling, Svenja Halfter, Liv Cornelissen, Alina Madita Wieczorek and Jasmin McInerney. And to the families of our team, thank you for the love, patience and support you provided, making it possible to do the work we do.

Funding and support came from the New Zealand Antarctic Science Platform, National Institute of Water & Atmospheric Research (NIWA), Antarctica New Zealand, British Antarctic Survey, Fisheries and Oceans Canada, Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), New Zealand Defence Science and Technology, MAC3 Impact Philanthropies, Monash University, Programma Nazionale di Ricerche in Antartide (PNRA), Te Herenga Waka - Victoria University of Wellington, University of Otago/Te Whare Wānanga o Otāgo, University of Waikato/Te Whare Wananga o Waikato. All of this is underpinned by wider support from the Ministry of Business, Innovation & Employment and the New Zealand Ministry of Foreign Affairs and Trade. I hope I haven’t forgotten anyone 😊.

And so, we draw this series of voyage updates to a close – thanks for reading. Now the analysis begins…after a wee rest.

Kia ora,

Craig Stevens

2024 02 19 LB in sea ice side on Lana Young

RV Laura Bassi sheltering in sea ice. Photo: Lana Young.

2024 02 19 sunset3 Lana Young

Sunset over sea ice in the Ross Sea. Photo: Lana Young.

This update was sent from the ship by New Zealand voyage leader Prof Craig Stevens and revised by the New Zealand-based communications team.