You never stop learning. That this is the core philosophy of our profession and the reason for our presence on the rough seas at 80°N in the Arctic goes without saying. But it also applies on a personal level.
Text and photos: Marie Stetzler.
After a first cruise on the smaller and cozy R/V Helmer Hanssen, a new dimension of ship-going-expeditions opens up to me here on the R/V Kronprins Haakon, to find methane flares… and have some unintentional bycatch.
On our arrival at the harbor in Longyearbyen in the polar night for boarding, the first noticeable difference to the R/V Helmer Hanssen was that it was not just a ship waiting for us at the dock, but a floating building. Ten decks high, illuminated with uncountable lights, as if someone was a little early in their set up of fancy Christmas decoration. The view is both impressive and exciting. As soon as we set foot on deck, we enter a world that is both a 4-star hotel and a high-tech lab. This will be our home for the next two weeks. You can easily get lost on various decks, rooms, labs, and the hangar on the first day, which is reason enough to explore every corner of the vessel, including the outside decks. You quickly learn that the heart of the ship is the mess, all paths lead to it and the meals are delicious. And deck nine, almost the ship’s highest, is immediately identified as my personal crow nest. Another surprise that awaited my fellow rookies and me in the hangar: having a huge hole in the ship’s hull can actually be advantageous. The big hatch, called “moonpool”, opens indeed directly into the open sea, as the constant stream of water rushing in and out of the pool confirms. It is used for the deployment of our underwater robot, the ROV (Remotely Operated Vehicle). This jewel of technology is our eyes and hands underwater. It will serve both the microbiologists on board by taking sediment probes, which are biogeochemical registers of past and present seepage activity. As for the geologists, it will gather data about the bubbles that are necessary for an assessment of methane in the water column, as well as catch some for analysis. The multibeam (a type of sonar) will guide our efforts by showing us where to find the flares. Water column sampling will tell us how the methane venting affects the ocean’s chemistry and biology.
But all these measurements have one prerequisite: finding flares! We know from previous surveys in the area that we are on the safe side, activity has been reported in our area north of Svalbard multiple years ago already. And indeed, a survey with the multibeam reveals the presence of flares. They don’t seem very prominent, but they have the merit of existing and we deem the biggest one worth a visit by the ROV. Only… the visibility of the ROV is just a fraction of the multibeam’s coverage. The coordinates of the flare are known, but hunting for it in the area still equals searching for a needle in a haystack. Except that this haystack is the 170 m deep, with gravel, sand, and sponge covered seafloor. Bubbles in this background are merely a passing shimmer. Patience and a sharp eye are our friends as the robot hovers through the water. The seep must be close, all the signs are there: carbonate crusts and white bacterial mats. Until, yes, we see single bubbles rising through the water. The camera zooms to its source. Our load of measurements can now be deployed. Let the seep-science begin!
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Or so we thought. After having already deployed a couple of instruments on the seafloor, the ROV dove down again, this time with the bubble catcher to collect some bubbles over the seep site. But we’re not alone in the sea. On the descent, the ROV crossed a dense swarm of fish attracted by the lights, unintentionally transforming the bubble catcher into a fishing device… In the transparent gas collector, several of them got trapped. Not being the cleverest creatures, they keep swimming upwards in the opposite direction of the exit. Turning the bubble catcher to the side, shaking it… nothing helps, the fish stay stuck. The ROV has to surface and get rid of them before pursuing the experiment. Finally, the “fishless” catcher got deployed and could collect some seep gas. From now on we had located other good flares and the rest of the measurements could go on. Maybe the ship crew even got fresh fish for dinner that night?