British Antarctic Survey recently led the highly successful BIOPOLE Southern Ocean Cruise I (Nov-Dec 2023), which was the first ‘formal’ scientific voyage of the RRS Sir David Attenborough (SD033). Taking place over 10 days in an otherwise logistic-heavy six-week schedule, BIOPOLE I was the first funded scientific project undertaken on our new research vessel. The objectives of this cruise addressed a range of Tasks under Work Packages 1-3. It sought to understand the role that annual sea ice retreat plays in setting the conditions for the spring bloom and how this bloom acts to draw down carbon from the atmosphere and sequester it in the deep ocean. In addition, the fortuitous placement of the A23a megaberg allowed us to undertake opportunistic sampling of how the colossal chunk of the Filchner ice shelf, first calving in 1986, is modifying the physical and biogeochemical properties of the surrounding ocean as it moves northwards. This ‘encounter’ with the world’s largest iceberg and the associated drone footage also generated massive media interest across the globe.
BIOPOLE I was undertaken by an 11-person science team, including BIOPOLE scientists Andrew Meijers (Principal Scientific Officer, physics), Nadine Johnston (ecosystems), Gabi Stowasser (ecosystems), Alex Brearley (gliders), Petra ten Hoopen (data manager), and BIOPOLE PhD student Laura Taylor (biogeochemistry), brilliantly supported by BAS Antarctic Marine Engineering, IT, data and lab management personnel, during an intense 10-day period in early December. The small team was ably backed up by significant shore-based support, both for glider piloting but also troubleshooting, sample and data processing. The survey section stretched across the rapidly retreating ice edge from the northwest of the Powell Basin to well into the Weddell Sea and 100% pack ice; and back out again. Over 1640 individual water samples were taken from the more than 30 CTDs, along with 10 Mammoth and almost 30 Bongo net deployments. The voyage also deployed three autonomous gliders, including two capable of novel under-ice navigation. These presently remain in the water following the development of the spring bloom and further retreat of the ice, and are providing greater spatio-temporal context to the ship-based process study. Additionally, personnel were craned onto the sea ice to collect sea ice cores in support of BAS PhD projects, and a mooring rescued at short notice from the path of A23a.
BIOPOLE I’s objectives were to determine the dynamics, biogeochemical composition and structural change in the upper water column as the ocean moves seasonally from being fully ice covered to fully exposed, as well as determine the structure and composition of the spring phytoplankton bloom and associated mesozooplankton community, particularly the copepod Calanoides acutus. The emphasis on copepods is part of the core BIOPOLE objective of quantifying the lipid component of the biological carbon pump. Over the course of their development, C. acutus develop a large carbon-rich lipid sac, primarily to fuel their metabolism and aid buoyancy during their winter diapause (a form of hibernation used to survive low food levels and avoid predation) at depths of (potentially) up to 2500 m. This deep diapause acts to transport carbon from the atmosphere to the deep ocean, but this transport has never been quantified despite the vast biomass that copepods represent.
Using a combination of respiration experiments together with investigations of their lipid sac concentration and size, population structure, distribution, and abundance, we can determine how much carbon this species is capable of transporting to the deep ocean, and its influence on nutrient recycling in the upper water column. The results of this cruise will be complemented by work carried out in the austral summer of 2022/23 onboard RRS Discovery (DY158) and a further BIOPOLE cruise in the austral autumn of Feb/Mar 2025 onboard RRS Sir David Attenborough where the late season condition of copepods will be assessed.
Despite fears of ‘first cruise’ teething issues the ship and personnel performed near perfectly. The SDA demonstrated its great capabilities; switching speedily between logistics and science, and easily handling challenging ice conditions, all whilst providing an unprecedented level of comfort for expeditioners! As ever a massive thank you must go to the officers and crew of the SDA, for delivering successful science with enthusiasm and skill, as well as to the science and support party who pulled together and supported one another at all times to produce some excellent and exciting new data.
BIOPOLE also attracted extensive media coverage during this cruise. The opportunistic science carried out at megaberg A23a had a high media profile, with the article initially in BBC News online leading to a number of further interviews by the global press of a number of scientists on board. These included lengthy interviews with Andrew on the BBC news channel and news hour as well as CBS streaming news, Laura on CBC News Canada, and Alex on CNN’s Tik Tok channel! Nadine gave interviews on the BIOPOLE 1 cruise and A23a on BBC Science in Action, BBC Inside Science, and BBC’s World tonight. Nadine also participated in STEM learning’s 2023 Protecting Our Planet Day Protecting Our Ice Session which was led by BAS PhD student Rosanne Smith and broadcast live from the RRS SDA and Rothera Research Station, and viewed by 54, 696 people (51,600 young people and 3, 096 adults).