Otago Biochemist explores Antarctic waters

Walls of sea ice, penguins and whales, mountains, history, and creatures from the icy deep - just a selection of what Emma Downer, an Otago Biochemistry assistant research fellow in Dr Nathan Kenny’s research group, saw on an amazing voyage through Antarctic waters recently. She was part of a scientific expedition where she gathered samples of invertebrates to look for convergent signals of molecular evolution in response to extreme cold. Emma kindly recounts her adventures here for us.

The ACTUATE voyage was a trip aboard the Research Vessel (RV) Tangaroa around the Ross Sea, which is pretty much a straight shot South from Aotearoa. First, we went to Mount Melbourne, a 2733m tall ice-covered stratovolcano. We then travelled to Franklin Island, a small shield volcano with an Adélie penguin colony huddled on a brown beach at the bottom of sheer black cliffs. Due to record low levels of sea ice, we were able to travel the furthest south the RV Tangaroa has ever been, right down to the Ross Ice Shelf, a daunting 487,000 km² wall of floating ice several hundred metres thick. A few days of steaming along the ice shelf eventually landed us face to face with Mt Terror and Mt Erebus. I swore the air was glittering with ice crystals blown up from the strong katabatic winds, and then I learnt that Erebus spouts 80g of gold vapor every day! Then we were off to Cape Hallet, Coulman Island, and then Cape Adare in Robertson Bay. Cape Adare is the site of the first official landing on the Antarctic continent in 1895, when the first geological samples were taken. We were able to see the huts that were built for the first over-wintering in 1899, which are currently hosting some of the world's largest Adélie penguin colony. Finally, we departed Northwards from the Possession islands, a group of rocky pillars sprouting awkwardly from the ocean. We had many beautiful sunshine calm days, snow flurries, gusting winds or sudden blankets of thick sea fog.

We were aboard for a little over 5 weeks, including the 8-day transit to get there and another 8 days to get back. An international assortment of 20 scientists were onboard, including scientists from Australia, Italy and India, for a wide range of different science objectives. I was sent to represent Nathan Kenny and the IDEA (Invertebrate Diversity, Evolution and Adaptation) Lab, collecting tissue samples from animals trawled from the coastal benthic environments. I sampled from a broad variety of animals, including molluscs, bryozoans, sponges, ascidians, corals, worms and echinoderms. Tissue was preserved for transcriptomic and genomic analysis, with the future aim of studying convergent molecular signals of cold adaptation in highly diverged groups. As well as biological sampling, the voyage included sampling of the atmosphere, water and sediment. Acoustics were used to monitor zooplankton and fish populations and map the sea floor. A towed underwater camera enabled live streaming of the sea floor, to optimise selection of locations for benthic sampling and improve models of biodiversity distribution. Pelagic sampling of zooplankton and mid-water fish complimented eDNA and acoustic methods of estimating diversity and abundance. Lastly, a number of moorings measuring oceanographic variables such as temperature, salinity and current were deployed, and moorings deployed in previous voyages were recovered.

I had the privilege of meeting a lot of talented and interesting people, and it was wonderful to learn about the different projects people are working on. Dr Ira Cooke, from the James Cook University (Queensland, Australia), was collecting samples for genetic analysis to improve models on whether the Western ice sheet, a critical point of uncertainty for sea level rise under climate change projections, melted during the last interglacial period. Previous work was based on population connectivity between octopus at different localities, with Ira collecting samples to supplement this dataset with more octopus and samples from other taxa.  Dr Hugh Carter, from London's Natural History Museum, recently uncovered the coordinates at which some of early Antarctic explorer Ernest Shackleton's samples were collected (when a student found a loose bit of paper in the back of his diary!). This enabled him to re-sample the same locations for direct taxonomic comparison to Shackleton's original samples. Dr Gert-Jan from the University of Otago is developing methods of eDNA sampling using sponges, which collect debris from the environment. As he can now definitely attest, collecting eDNA from water is an extremely time consuming and tedious task. Additionally, sponges are often pulled up as by-catch during long-line fishing, thus sampling sponges would enable fishing vessels to easily collect samples for researchers to assess fishing stocks and ecosystem health. I also thoroughly enjoyed meeting the friendly and highly skilled crew, who come from all walks of life and run a very tight ship. The cooks and steward were wonderful, and we were eating homemade baking, salads and fresh fruit until the very end.

One highlight of the trip was passing through an ice-bridge, a vast band of sea ice that pops up seemingly out of nowhere. We were still a day or two away from seeing land, crossing through the sweet spot where open ocean currents outside of the sheltered Ross Sea keep the water cool enough to stop the ice from melting. Phytoplankton collects on the bottom of the ice, driving primary production and feeding energy all the way through the trophic cascade to produce a hotspot of penguins leaping through the water and showy humpbacks flashing their tails. The first icebergs were ginormous, stark whites and electric blues in all sorts of different shapes and sizes. The next day we did not see a single bit of ice, like we had dreamed it all up. My favourite day of the trip was spent at Coulman Island. The afternoon was thickly foggy with flurries of snow, a perfect wintery scene with clouds rolling down the island like slow motion waterfalls. By the evening, the moodiness had moved on, and we enjoyed glassy waters reflecting snowy peaks like a mirror against a never-quite-setting sun. A couple Minke whales came to check us out, with one of them swimming right along the side of the boat. It was extremely beautiful and surreal. I feel hugely privileged to have been able to visit such a pristine environment. The experience strengthened my passion for marine conservation and made me think critically about the trade-off between the potential environmental benefits of scientific research relative to the costs of undertaking it. I want to continue in my scientific career with this carefully in mind to ensure the scales are tipped in the right direction.

I was extremely fortunate to be fully supported by Dr Nathan Kenny with the IDEA Lab and the University of Otago. I am hugely grateful to Nathan for this once in a lifetime opportunity, and for helping me patiently through each step of the process to make it all happen.

You can find out more about the voyage here:

Ross Sea “ACTUATE” Voyage - TAN2502

Find out more about Nathan Kenny's research group here:

IDEA Lab