MAREANO cruise summary: To Bjørnøya, beyond, and beneath!
This is the first MAREANO cruise of 2019 and will see biologists, geologists and chemists working together onboard to video the seabed and collect samples of the sediments and seabed-dwelling animals between 30 and 2200 m water depths. The data will be used together with multibeam bathymetry and backscatter data recently acquired by our MAREANO partners Kartverket and legacy multibeam data from the University of Tromsø. These data allow us to not only ‘see’ the shape of the underwater terrain, but also to gain an impression of whether the seabed is soft or hard and how rugged it is. The bottom types will be verified by the data acquired on this cruise, together with information on which animals inhabit the sea floor and its environmental status. The new knowledge acquired by this, along with other MAREANO surveys, provides important information that helps facilitate the sustainable management of Norwegian sea areas.
By Sunday evening, after sailing northwards for over 24 hours we arrive at the first station ready to deploy the video rig “Chimaera” for the first dive of the cruise in near perfect weather conditions. The first few days of work are jam packed with video surveys from the shallow waters to the north of Bjørnøya, where we observe many sandy high energy habitats and even a 257 million year old fossil!
Once outside the protected area around Bjørnøya we start supplementing our video observations with physical samples of the seabed. Several grab samples are taken so that MAREANO geologists can verify grain sizes (sand, mud etc.) observed in video footage. At selected stations a full suite of complementary sampling is conducted to contribute to the MAREANO database. The images below give a flavour of some of the equipment used and samples obtained.
As we move further west from Bjørnøya into the deeper water habitats of the Kveithola Trough we see how rapidly the habitats change over a short distance as we move away from high energy, current swept shallow waters where many animals are prominent in video images into a calmer environment where more animals make their home within the sediment, less visible on video but clear to see from physical samples.
As we reach the shelf break and deeper waters below 500 m the remoteness of the seabed hits home as all the equipment takes longer to deploy to and from the seabed. Nevertheless, it’s all systems go as we continue to work 24 hours a day to gather more video and sample material from the slope, including from an underwater landslide. Some areas here have clearly been recently trawled and we can see several fishing boats around us, likely in search of cod.
Whilst we are sampling at just over 1000 m depth, however, the good weather we have enjoyed since arriving in the area almost exactly a week ago, breaks. As the waves grow steadily higher, the white horses roll, and the ship sways, all deck operations are put on hold for around 24 hours. By Monday morning the seas have calmed a little and, although seas are too rough to deploy the video rig, grab sampling can continue allowing geologists to verify which sediment types our multibeam backscatter data correspond to, as well as taking some surface samples for geochemical analysis. After a few more hours with grab sampling the conditions are finally calm enough for the video rig to dive again. Some more stormy weather is forecast which looks to threaten the rest of our sampling programme and send us back to port, but lady luck is on our side and we manage to escape without any major further loss of survey time.
MAREANO has not conducted video and sampling in deep waters since 2012 but we enjoy several video dives to over 2000 m in the last days of the survey, as well as completing our planned geochemical programme with a final multicore sample. One event worthy of particular celebration was MAREANO’s 2000th station at around 2160 m, the video rig was even decorated for the occasion and spirits on board were high.
During the last day of survey operations, we have conducted the final video surveys, albeit with a bit of prioritizing of stations to fit the time available. We also managed to return to complete some important unfinished stations where we were originally unable to deploy certain equipment due to bad weather. Overall, given the time of year we have been very fortunate to have come so far with the survey operations and have gained a good impression of the seabed and its inhabitants across the whole area. Now it is time to set sail for Tromsø and enjoy a well-earned break over the Easter weekend.
MAREANO wishes to thank the Captain and crew of G.O. Sars as well as the IMR instrument technicians. We look forward to more video and sampling surveys later in the year when the MAREANO team will set sail again.
For further details from this cruise please see the following news articles on MAREANO’s Norwegian pages: