15. August, 2014
After a short but successful visit to the hydrothermal vent field in the Kolbeinsey area, we hurried to our final destination of this cruise: Loki’s Castle, a large vent field with the world’s northernmost black smoker. After its discovery in 2008 during a Centre for Geobiology cruise, many of us have been involved in research on the geology, geochemistry and biology of this field – but more samples are needed to continue with this. With weather gods being on our side this year (apart from the transit back to Tromsø at the end of leg 1, we have mainly seen a flat Arctic ocean) and the ROV operations running smoothly so far, everything seemed to be ready for a great finish of the cruise. The 38 hour transit was used by most of us to rest a bit, finish the work on samples collected in the previous days at Kolbeinsey and Jan Mayen, or prepare for the new operations at Loki’s Castle.
Work during transit: dividing the microbial mat (the milky-substance in the big bottle) between all the researchers that would like to work with it.
Work during transit: Desiree performing incubations in a glove bag that is filled with nitrogen-gas, to create an anoxic atmosphere
Unfortunately, Murphy’s law kicked in just when we arrived at location. After the ROV had reached the 2500 meter deep seafloor on Saturday afternoon and started its first operations, we were suddenly staring at a pressure gauge that showed what everyone feared: no hydraulic pressure to operate the arms, the chainsaw, the suction sampler (a huge vacuum-cleaner like apparatus that can suck up biological samples from the seafloor), or anything else running on hydraulics. There was no other way but to recover the ROV and hope that Frank and Erik, the Argus pilots, could fix it.
As cruise time is precious, we switched immediately to plan B. Many of us were hoping for small sediment cores from the hydrothermal barite-rich sediments that would be collected by ROV (so-called push cores), but with more hydraulic oil outside than inside the ROV this scenario seemed to get more and more unlikely. Enough reason for some of us to skip sleep and try to get a larger gravity core from this area during the night. However, as the vent field is deep, the sediment pond small and the currents strong, it is difficult to get the core in exactly the right location using only the winch from the ship. Whether it was plain luck, or perhaps the transponder that we mounted on the corer and sent out its approximate location so that we could position the ship exactly in the right spot, by 5:00 am we recovered a beautiful 2.07 m core of reduced hydrothermal sediments. The coring-crew (Desiree and Anne) couldn’t help but to do a little dance of joy in the hangar afterwards (we just hope no-one was watching the camera).
The sediment core from Loki’s Castle.
Still not much luck with the ROV the next day, but as nicely pointed out by Hildegunn – one of the geochemists – the cores had provided everyone with enough work to do. Surely that was true for the microbiologists who nearly sampled the entire core…
Pål Tore sampling the top of the core for nitrogen-cycling experiments.
Håkon sampling nearly the entire core for microbiology 🙂
The last hours of the cruise time were spent keeping our fingers crossed when the repaired ROV went down to deploy Ingeborgs last incubators at Loki’s Castle, and finishing the CTD festival on the Mohns ridge – before setting off to the second CGB pubcrawl in Tromsø.
Although some of our plans may not have worked out as hoped for when boarding the G.O. Sars, there were nothing but happy faces when we left the ship and headed to the airport for our flight back to Bergen. After all, cruise-based research comes with both exciting new discoveries and frustrating failures of equipment, but all of us managed to get hold on new samples that should keep us busy until the preparations for the 2015 cruise start again.