Diving in the Arctic: ICE-cruise 2011 blog
The team consists of four experienced Arctic divers: Peter Leopold and Ireen Vieweg from Germany, Sanna Markkula from Finland, and Haakon Hop, Dive Master at the Norwegian Polar Institute. Diving in the Arctic for scientific purposes requires special gear for diving in very cold water with temperatures below zero.
Saltwater freezes at -1.9°C, and it is often close to freezing temperatures below the ice. We therefore need to use dry suits with warm underwear, full face masks and regulators with frost protection to prevent freezing. If a regulator freezes in the frigid Arctic waters, the diver will lose all the air in the tank within minutes. This is called free-flow, and even if we take precautions – this still happens. On our dive today, two of the divers had to return to the surface because of free-flowing regulators.
Another challenge, when diving below ice is how to get on the ice and into the water. On our first ice station, the ice was much broken up into smaller floes, which were so densely packed that it was difficult to find an opening to get in. We finally managed to move some ice around so that we could thread ourselves down between some ice floes and get under the ice. We use a line with communication for diving, and it would be very difficult to find our way back to the small hole without this line. The line tender on the ice feeds out line and keeps in contact with the diver. Our first dive was on a floe close to our research vessel Lance, and it was therefore quite noisy from below. We can hear the engine and propeller and also sometimes people talking and music. We also heard seals vocalizing, with sounds that carry a very long distance. So, the silent underwater world is often not that silent to a diver.
During the dive below ice we have different scientific task to perform. We collect samples of ice algae growing on the underside of the ice. This spring cruise in April-May is particularly interesting in that regard since we cover the spring-bloom situation. Ice algae typically start to grow at very low light conditions below the ice during early spring, in April-March, and then the pelagic production with ice-edge blooms of phytoplankton starts around now in early May. During our first dive, the ice was quite thick, about 3.5 m, and with 0.5 m of snow on top. Since the snow blocks out 90% of the light, there was no ice algae and also pretty dark below the ice floes. We need to dive with lights to be able to see anything. There were some sediments entrained in the ice, which indicated that these floes were likely small remnants of multi-year ice, which may have travelled all the way from the Siberian coast to the area north of Svalbard – a journey which may take 3-4 years. There were some ice amphipods of the species Gammarus wilkitzkii and Onisimus nanseni below the ice, but at very low abundance. We use electrical vacuum cleaners and 50x50 cm frame to try and get some quantitative estimate of their abundance, but on this dive there were just too few to even try and get a sample of them. So, our fist dive mainly became a test dive for divers and equipment, and it was then back to the dive-lab to fix gear and modify for future dives.
Today, the ship moved in towards the coast to pick up a helicopter from Longyearbyen, and we took the opportunity to go for a dive near Raudfjorden at 22–25 m depth. The visibility was quite good, 7–8 meters, since the spring algal bloom has not really stated and we had a nice dive to a bottom of rocks and some sandy banks. We used shovels to dig for clams and found some Mya trucata, a type of clam that has a long siphon pointing up at the surface. They typically sit 20–30 cm down into the sediments, but since the sand was quite coarse it was easy to dig them up. We got about 25 clams, which will be used in a study of growth related to climate. When the water is warming up, the clams grow faster, and this can be seen in the annual growth rings on their shells. We also saw a strange stauromedusa, a type of jellyfish that is attached upside down on the bottom. Its scientific name is Lucernia quadricornis, and it has 8 arms with tentacles. The interesting part about diving is that we always see something new on our dives, and there are often some surprises in these unknown waters. Chilly on the hands for sure, and some free-flowing problems, but this is also part of the game for Arctic divers.