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RV Polarstern through the fog
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BIOPOLE at the North Pole

On the 2nd August 2023, I (BIOPOLE researcher Dr Kathryn Cook, University of Exeter) joined the RV Polarstern in Tromsø, along with project partners Morten Iversen and Sinhue Torres-Valdes (AWI), to participate in the 9-week ArcWatch 1 (PS138) cruise to the central Arctic.  The overall aim of the 50 scientists participating on the cruise was to study the physics, chemistry, and biology of the sea ice, but I was invited along to collect samples to help address BIOPOLE WP2 deliverable ‘What controls the depth at which polar copepods diapause, and their physiological rates during overwintering?’.

I used a Hydro-Bios Midi Multinet (thanks to project partner Barbara Niehoff, AWI) to sample the important Arctic lipid storing copepods Calanus hyperboreus, Calanus glacialis, and possibly the northern North Atlantic interloper Calanus finmarchicus (we’ll have to wait for molecular confirmation to find out) throughout the upper 1500m of the water column.  I was also able to take samples from immediately below the sea ice using a net attached to an ROV affectionately known as ‘The Beast’.  We took samples at 9 ice stations, including the MOSAiC station and the North Pole.  These samples will be used to quantify the biomass (carbon and nitrogen), lipid content and composition, and estimate the metabolic rates using enzyme assays (Electron Transport System (ETS) activity as a measure of respiration rate; Amino-Acyl-t-RNA-Synthetases (AARS) activity as a measure of growth).  These data will be used to inform life-cycle food-web models and will be available to WP3 to help develop simplified, global parameterisations of the lipid pump and improve estimates of the amount of carbon sequestered in the mesopelagic ocean.

First steps on the ice. Kathryn Cook (University of Exeter)

As well as being very successful scientifically, this cruise was, by far, the most exciting research trip I have been on in my career to date.  Just getting out on the sea ice was amazing, but we also had helicopter excursions to measure ice thickness, a polar bear coming to play with ‘The Beast’, live footage of sea mounts and hydrothermal vents courtesy of the OFOBS (Ocean Floor Observation and Bathymetry), live music courtesy of The ArcWatchers (featuring project partner Morten Iversen) and of course being, literally, on top of the world.  We were accompanied by a media team who wrote regular social media posts, blogs (Arctic August – October 2023 – AWI Polarstern) and German newspaper articles, as well as a documentary film crew.  The documentary ARCWATCH – HOPE IN THE ICE was broadcast on 29 December 2023 at 9:45 p.m. by German broadcaster ARD and is available (in Germany) in the ARD Media Library.  There should be an international version released at some point, so watch this space.

Wrestling ‘The Beast’ with net into a hole in the ice to sample under ice copepods. L-R Kim Vane (AWI), Emiliano Cimoli (University of Tasmania), Marcel Nicolaus, Julia Regnery (AWI).

The author of the blog – Kathryn Cook (University of Exeter)

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Team BIOPOLE in the Arctic

Since 1999, the Alfred-Wegener Institute (AWI), has conducted long-term ecological research in the Fram Strait, the passage between East Greenland and Svalbard. In June, Katrin Linse and I joined for this year’s ‘HAUSGARTEN’ expedition on board the research vessel and icebreaker, Polarstern.

This was a fantastic opportunity to collect data with BIOPOLE project partners from AWI (Barbara Niehoff and Sinhué Torres-Valdes) and the Senckenberg Institute (Saskia Brix) which would span the breadth of BIOPOLE’s aims: to understand how nutrients and ecosystems in polar environments influence global primary productivity and carbon cycling from the surface to the seafloor.

With spectacular sea ice and blue skies, the BIOPOLE team worked seamlessly under the midnight sun to sample over 30 stations in just as many days. Katrin and Saskia used an epibenthic sled for the first time in the region to sample the sea-floor animal community; Sinhué and I used an auto-analyser to infer the inorganic and organic nutrient profile of hundreds of water samples; and under the guidance of Barbara, plankton nets were deployed to collect our favourite Arctic zooplankton – copepods. Furthermore, a BIOPOLE-funded Remote Access Sampler (RAS) was deployed as part of a mooring array in the outflowing East Greenland Current, complementing others deployed in the inflowing West Spitsbergen Current.

The data collected will contribute to BIOPOLE work packages 2 and 3. Analysing the nutrient make-up of water flowing out of the Arctic is fundamental to the aims of WP3, and the strategic placement of the HAUSGARTEN stations and RAS will help provide high resolution spatial and temporal coverage within this key Atlantic gateway area. A key aim of WP2 is to refine our understanding of the lipid pump, a process driven primarily by the seasonal vertical migration of polar Calanus copepods. One understudied aspect of this process is the interaction between Calanus and the benthic community. The epi-benthic sled allows for simultaneous sampling of these two communities and subsequent elemental and lipid analysis will offer new insights into bentho-pelagic connections.

Data aside, an important outcome from this expedition was the close interaction and teamwork between BIOPOLE members and partners which is set to continue through future cruises, data sharing and meetings. As an early career researcher, I’m incredibly grateful to the whole BIOPOLE and AWI/Hausgarten team for sharing their knowledge, skills and experience in many ways; from training me in chemical oceanography and mud-sieving, to helping with species identification and general navigation of working at sea. It was an incredibly enriching experience.

The whole BIOPOLE team would like to express our sincere thanks to the Captain Thomas Wunderlich, PSO Thomas Soltwedel, and all scientists and crew for their wonderful support, hospitality and atmosphere on board. For more highlights (including polar bear encounters), read more on the Polarstern blog here.

Copepods were sampled, identified and imaged from the surface to over 5000m deep. Credit: Jen Freer

Copepods were sampled, identified and imaged from the surface to over 5000m deep. Credit: Jen Freer

The author of the blog – Jen Freer (British Antarctic Survey)