Last update saw us achieve Tangaroa’s farthest south science where we recovered our RISIPE moorings from just a few kilometres north of the Ross Ice Shelf front. From there we headed west to a bay on the north side of Ross Island, nestled between Mounts Terror and Erebus, to set up for a benthic survey for a virtually unsampled location. The seafloor around the island is poorly mapped on the marine charts at the scale required for the sampling, so we spent the first part of our time there scanning the seafloor with a Multibeam Echosounder sonar.
This sonar technique uses a transducer in the ship’s hull to map the seafloor and create high-resolution images for the science team to plan their sampling. In addition, it gives the ship’s bridge officers confidence about the depth. NIWA’s Alicia Maurice operates the seabed mapping controls, working out the best lines to survey and fine-tuning the sonar for the conditions, in order to build up a detailed picture of the seafloor. It all sounds easy but with our present mode of operation there’s quite a bit of time-pressure. As soon as the new map emerged from Alicia’s survey, the benthic sampling team were using it to target their upcoming sampling.
One of the main tools for the benthic survey work doesn’t take any physical samples at all. It is a towed camera system that gives the team real-time high-resolution video - NIWA’s Deep Towed Imaging System (DTIS) has been evolving for different needs over the last 15 years. Its main advantage is it can be used to survey large seafloor areas quickly and, in a modestly priced package, provide high-resolution, geo-located imagery in a way that integrates with other data being collected. Jacob Hall and Nick Eton have been extending this technology.
A ship is constantly moving in the swell, and it is a lot of heavy machinery moving in different directions. And yet we scientists continually turn up with delicate instruments to get in the water! It’s a credit to the ship’s deck crew and Bridge officers that they find a way that works for everyone. Recent improvements to DTIS now make controlling the package much easier, with improved visual displays for the winch driver and camera operator, which in turn enables the video to get much closer to the seabed. At the same time, NIWA’s recent investment in fibreoptic cable means that the imagery coming up the line has better clarity than ever. These cost-effective, behind the scenes, developments are among the many underpinning components making the voyage possible.
Cape Hallett, around 125 km south of Cape Adare on the northeast tip of the Victoria Land region, used to have a joint NZ-US research station up until the early 1970s. The Italian team we worked with last year (Pierpaolo Falco and others) have maintained an ocean mooring and collected some sediment cores close by Hallett, in Edisto Inlet - and indeed as we were working, the Laura Bassi passed close-by to collect some instrumentation. It was a nice interlude to be exchanging WhatsApp messages with our friends and colleagues, at the same time as waving to them.
The Italian sediment work looks at evidence of the changing ice sheet over the last ten thousand years through to the present. This, in turn, forms the basis for a benthic ecosystem which has developed over that time to become the modern system we are cataloguing.
En route to Hallett we’d picked up our ocean glider Manaia that had been working its way north over a ten-day period. It would have been nice to let it sample a little longer, but our schedule is a fine balance built around the drifting sea ice, the weather, and our looming departure deadline, and it doesn’t take much for things to come unstuck.
The glider pickup point was around 4 hours offshore, so we had the leave the stunning coastal scenery of Coulman Island behind and go on what seemed like a leap of faith to a GPS position sent out by a mostly submerged, two-metre-long tube, in a vast ocean. However, as we cautiously, lest we run her over, approached the mark, Manaia - with its yellow tail in a flat sea - turned out to be very easy to spot. A quick trip in the work boat for Dr Jasmin McInerney and crew, and we had our data-filled ocean robot back on board.
Manaia’s mission was two-fold. Ther data set will be used to help establish how water moves down the Drygalski Trough, with a focus mainly on the physical transformation that takes cold, salty, oxygen-rich water from coastal polynyas to the deep sea and exchanges with warmer waters offshore.
The second aspect this data will contribute to is new work looking to connect biology to physics in this unique environment. This work was initiated during the 2024 Laura Bassi joint Italy-New Zealand voyage where a collaboration between early career researchers from both nations was funded – thanks again to the ASP - by MAC3 Impact Philanthropies, in order to build their networks and profile.
For our 2025 Tangaroa ACTUATE voyage, NIWA provided Strategic Voyage Funds to enable Drs Alina Madita Wieczorek, Svenja Halfter and Jasmin McInerney, who had all been funded by MAC3 in 2024 to continue this work in order to cross disciplines and trophic scales by connecting physical water column structure and particulates from the glider, with acoustics, eDNA and net sampling. This type of interdisciplinary perspective will be fundamental to providing early awareness of large-scale biological changes forced by a warming climate.
Support of early career researchers (ECR) has been a real strength of this voyage. One of the many nice things about this voyage has been the demographic balance with the old hands and also ECR and students, some of whom will become tomorrow’s leading researchers. This sense of positivity is added to with the science team’s gender balance being 11f:9m, as well as Jenny, Marissa, Ninja, Erica and Jo on the ship’s complement, all building on the sense that we are very much a future-facing enterprise. From these coastal sites, we will move to deeper, more exposed waters to maintain some of our critical long-term ocean observing infrastructure.
Craig Stevens (co Voyage lead with Denise Fernandez).
