EMSO-Azores: the Momarsat 2021 cruise

The Momarsat 2021 cruise ended on Monday, June 14th, after 21 days on site at the Lucky Strike vent field along the northern mid-Atlantic ridge to carry out the maintenance of the EMSO-Azores observatory.  A team of 20 scientists from Ifremer, CNRS (IPGP, GET, MIO, LPO) and the University of Western Brittany (UBO) sailed onboard the French Research Vessel L’Atalante to the Lucky Strike vent field off the Azores. The French manned submersible Nautile performed 18 dives to ensure work on the seafloor. The scientific team was composed of 5 researchers, a PhD student, a post-doc, and 13 engineers and technicians to ensure the maintenance of the observatory and autonomous sensors.

© MOMARsat 2021

The two stations, SEAMON (Sea Monitoring Nodes) East and West, and the surface buoy BOREL were recovered and redeployed after a week of on deck reconditioning. The observatory is now fully running, and data are flowing in near real time: http://www.emso-fr.org/charts/azores/.

This year, we added an EGIM, EMSO Generic Instrument Module on Seamon West node, located in the fossil lava lake, away from hydrothermal vents. This module will allow the long-term monitoring of background seawater dynamics. On the East node, we connected for the first time the fluid sampler DEAFS that sequentially collects end member fluids from a bell deployed directly on a smoker.

The thermometer chain (H2020 iAtlantic, grant agreement No 818123) deployed in 2020 was damaged over the year as a result of the high temperatures encountered on the structure and was not redeployed this year. Despite this, 66 thermometers out of 100 were able to register temperatures.

In addition, work at sea allowed the repeated in situ collections of fauna, fluid, rocks and the measurements of a number of parameters that complement the temporal monitoring of the vent sites while extending the spatial extent of our studies.

An exploratory experiment in physical oceanography aiming at studying local microstructure turbulence was carried out in between dives. Seventeen VMP (Vertical Microstructure Profiler) and CTD profiles were performed over the cruise.

Sharing our experience at sea and raising awareness is also part of our objectives. A Facebook cruise log for the general public was produced during the cruise (https://www.facebook.com/CampagneMomarsat/). In addition, this year, an outreach project linked two scientists with a radio broadcaster and children from the Kerangoff social center in Brest to learn about the deep-sea and means to produce a radio show. During this adventure, the scientists had numerous exchanges with the children, including videoconferences directly from the cruise. Hopefully, these exchanges will inspire a final radio show to be broadcasted late June on the Brest local radio U.

The EMSO-Azores observatory is now starting its second decade of data acquisition, making it one of the longest multi-disciplinary high resolution monitoring infrastructures of mid-ocean ridge hydrothermal vents!