Small emperor penguin colony in the Bay of Whales. Photo: Lana Young.
Ross Sea Voyage Update #6: The Bay of Whales
We arrived in the Bay of Whales, an indentation on the eastern side of the ice shelf front, on the last day of January 2024.
James Clark Ross never made it this far southeast, so it was left to Shackleton to discover it in 1908. Three years later, Amundsen, aboard Fram, used the bay as a base for his return-trip to the South Pole. In the late 1930s, Richard Byrd set up Little America in the bay, which was occupied on and off by the US through into the 1950s.
This is a complex and highly variable region of the ice shelf, fed from the south as the ice flows around Roosevelt Island (the large ice-covered island where the RICE core was retrieved). Indeed, if you go a little further south you get to where the ASP Project One: Ice Dynamic's work at KIS1, KIS2 and SWAIS2C's KIS3 took place. Once we gather all our data the ASP provides a great opportunity to connect processes happening in the ocean with that taking place in and beneath the ice.
The Bay of Whales forms the southernmost point of the planet’s oceans that are accessible by surface vessel. In fact, the RV Laura Bassi increased the record last year, making it to 78° 44.280′ S. There was no such record for us this time, as there was a reasonable amount of broken multi-year and fast ice. The payback was that the ice enabled a fast-ice safety drill and the ship’s complement could disembark in survival suits. This was an amazing experience, but the nagging thought that the real situation would be far less fun (noting that the RV Laura Bassi icebreaker was formerly the BAS’s Ernest Shackleton).
The Bay of Whales is an indentation on the eastern side of the ice shelf front. The image is ~ 80km across. Photo source: NASA EODIS; 26/1/24
Seabed coring
One of the highlights of the trip for me was the joy at the return to deck of a successful multicore sediment sample for the University of Otago team, Meghan Duffy and Luisa Fontanot. They’d had a hard run trying to identify areas good places to core, because the voyage is not able to spend time doing tight surveys. Instead, they’ve to make do with lower resolution acoustic sounding to identify possible sites. However, a good spot revealed itself just outside the Bay of Whales and they retrieved an almost perfect collection of multicore and gravity core. Many hours of sub-sampling for various needs have kept them busy.
Deploying the multi-corer. Photo: Lana Young.
Luisa Fontanot as a successful core is retrieved. Smiling in the freezing cold is hard! Photo: Liv Cornelissen.
An abundance of life
Monash University’s Matthias Dehling’s patient logging of seabirds and marine mammals has him putting in many diligent hours in very uncomfortable conditions, as observations are best made from the exposed helicopter deck. Good counts were made in the sea ice of Terra Nova Bay, but this has dwindled in the mainly iceberg-strewn reach across the front of the shelf.
However, his patience was rewarded as we entered the Bay of Whales. Many of his counts for the afternoon exceeded the entire voyage to date. Skua of course, but various petrels, seals and penguins.
As the ship pushed through the sea ice, it became clear why there was so much life in the Bay of Whales. The multi-year ice flipped to reveal a greeny-brown underside – this helps drive the base of the foodweb. This is supported by as revealed in NIWA's Svenja Halfter’s net tows that captured all sorts of zooplankton (pterapods, krill, comb-jellies, amphipods).
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.
This voyage is collecting data to determine how vulnerable the Ross Sea region Marine Protected Area (MPA) ecosystem is to the future changes anticipated for this region.
Adélie penguin in the Bay of Whales. Photo: Lana Young.
Zooplankton specimen. Photo: Lana Young.
CTD profiles
Conductivity, temperature, and depth (CTD) rosettes are used to profile the water column, and to sample at specified depths for gases, nutrients, and microbial life. While our oceanography team have collected many CTD profiles in the Ros Sea region, the CTD station in the Bay of Whales is the furthest south ever occupied by a ship. The Italians took a CTD profile here and it supported what was obvious from looking at the sea ice.
There is clear evidence of ice shelf meltwater, as there were upwelled patches of platelet ice crystals as we pushed through sea ice. This occurs when the ice shelf melts at depth and the meltwater rises to shallower depths, at which point it becomes colder than the local freezing temperature and so refreezes, but as large platelet ice crystals. The result is a unique sea-ice structure built from an interlaced network of ice crystals.
The Antarctic Science Platform Project Four: Sea Ice and Carbon Cycle Feedbacks is investigating this type of ice formation in McMurdo Sound, and seeing it here shows how widespread the influence of shelf meltwater is.
Deploying the CTD rosette. Photo: Craig Stevens.
Leaving the Bay of Whales, we sailed essentially due north, with an acoustic sensor that images the seabed and the nature of the material in the few tens of metres below. This line worked up the trough running north. This continued to an old core site at around 77’S. The weather conditions were sufficient to enable the University of Otago team to retrieve a small core – enough to check surface properties. From there, we turned back to the ice shelf once more for one last CTD station before heading northeast.
Ross Ice Shelf in the Bay of Whales. Photo: Allegno Randubardi.
This update was sent from the ship by New Zealand voyage leader Prof Craig Stevens and revised by the New Zealand-based communications team.