Since the last update, we crossed over onto the continental shelf and turned westward, picking up moored instrumentation measuring temperature, salinity and currents. After the stunning icebergs and sea ice, this middle run was fairly non-descript. This continued as we arrived in the early morning at our coastal sampling station at Wood Bay near Cape Washington.
The coast was shrouded in low cloud and we could only just make out ice, rocks and snow along the shoreline. This left folks a little deflated about their first view of Antarctica. This all changed rather miraculously mid-morning when the clouds dissipated to reveal the high, rocky headland of Cape Washington itself, and then the stunning Mount Melbourne – an active volcano and something of a Mount Erebus doppelganger.
It was at this point that the benthic ecology team swung into action. Led by University of Otago - Ōtākou Whakaihu Waka Professor Miles Lamare, and supported by NIWA’s Dr Vonda Cummings onshore, the team is carrying out surveys and sampling that builds on a number of previous Tangaroa voyages. The benthic team were hand-picked by Miles and Vonda, and while you wouldn’t know it from the seamless workflow, none of the visitors had met each other in-person before.
The critical and unique seafloor ecosystems in the region are highly responsive to sea ice, temperatures and salinity. So, the team have developed a sequence of measurements from acoustic scanning, through to high-definition camera surveys and actual samples of the seafloor, sea life and water. This means the same work package incorporates the latest digital HD video, fibreoptic cable, eDNA (Environmental DNA) and precision satellite positioning. At the same time as a beam trawl and benthic grab that would have been at home on the back deck of HMS Challenger in the 1870s.
The video is captured by NIWA’s Deep Towed Imaging System (DTIS) and the data coming up the fibreoptic feed is astounding. Beautiful, clear imagery of the complex seafloor communities and individuals. What is equally impressive is the teamwork between DTIS drivers (NIWA’s Nick Eton and Jacob Hall) and the ship’s winch operators, in conjunction with several taxonomists working in real-time to identify key moments in the video to return to for more in-depth analysis.
It’s fair to say our international colleagues, from India, Australia, Italy and the UK, were all impressed at the quality of the DTIS imagery. To step into the darkened lab and hear combined radio chatter about winches and wire-out in parallel with the rapid-fire listing of species being observed through the video feed is energizing. Simultaneously, it highlights the vital role taxonomists play in understanding systems and change, and the benefits of bespoke home-grown technology development where needed.
The remotely sensed acoustic and video data of the seafloor are one thing, but when the benthic grab came on deck and you get to see the samples for real, it is another. All sorts of starfish, sponges, rocks, even fish, all spill out in a riot of colours and shapes and sizes. Furthermore, the video sampling means the physical sampling is as targeted, and minimal as possible.
Despite this targeted sampling, a voyage like this can collect a lot of samples in a short amount of time, so a good deal of care needs to go into corralling the researchers and sorting the samples. NIWA’s Dr Pamela Olmedo Rojas directs the sorting and storing, as well as monitoring the safe operations of the team in all sorts of conditions. This vital role enables us to come home with a structured set of samples, making the transition to shore-based analysis as smooth as possible.
Equally importantly, we need to know where the samples have come from. So, it was great to have University of Tasmania’s Senior Research Fellow Dr Nicole Hill aboard as she specialises in the intersection between mapping and biodiversity. The importance of the mapping rapidly becomes apparent when one sees of the seafloor gouges where icebergs had simply ploughed through erasing anything that can’t get out of the way. Only a few metres apart are communities hundreds of years old, next to an area where everything is less than two years old. Then, in addition to this natural regionality, the work is all imbedded within the Ross Sea Marine Protected Area, the largest MPA anywhere. Clearly, in order to protect something, we need to know what we are protecting, and where.
On days when sampling is light, we’ve been having science talks from various people aboard and we were fortunate to hear talks days before sampling from two of the taxonomic experts, Dr Ira Cooke (James Cook University, Australia) and Dr Hugh Carter (Natural History Museum, UK), about the species they were interested in. So, when the samples were being sorted we all had more of an idea about what was going where, and why. And, as well, we had enhanced respect for the implications of some of the rarer samples. The team are supported by University of Otago students Emma Downer and Fiona Schultz, as well as Italy’s Dr Marco Grillo, who continue to apply themselves to the many sampling tasks - when not looking out for whales, penguins, icebergs, orca and volcanos.
In parallel with all the physical sampling, the voyage has a lot of eDNA work going on. Some rather remarkable techniques have evolved over the last few years enabling the detection of genetic indicators in environmental material like seawater and seafloor sediments. So, the benthic team are rounded out by University of Otago Research Fellow Dr Gert-Jan Jeunen who diligently appears at regular intervals to grab buckets of water that then disappear for eDNA analysis in a “clean” laboratory container set up high on the port side, back-deck.
If the sea ice ahead lets us, we will repeat this effort at a number of locations, from around 50 metres depth through to over 200 metres deep. The reason we go to all this effort is primarily because it is a unique ecosystem - with the combination of very cold water, sea ice, icebergs and the light regime, as well as relatively little human presence. This whole system lives, and thrives, in a very narrow temperature range, so the potential for major change being caused by a warming ocean and increased meltwater is large. These unique data will help us understand where the ecosystem is at now, and where its headed. What happens in Antarctica, does not stay in Antarctica – changes around the southern continent will be felt in Aotearoa New Zealand in the decades and century to come.
From here we turn south for Franklin Island and the Ross Ice Shelf.
Craig Stevens & Denise Fernandez
