ANR-IRONWOMAN
d'après Ryan et al. 2009
MoMARSAT campaigns have taken place every year since 2010 and the installation of the EMSO-Azores deep-sea observatory at the Lucky Strike hydrothermal site on the Mid-Atlantic Ridge located on this map (red star)
Before the cruise
In March, we went to the Ifremer La Seyne site, to bring the material boxes so that they could be taken on board the N.O. Pourquoi Pas?
We will meet them at the boarding in Ponta Delgada at the beginning of June.
@Aina Astorch-Cardona
@Céline Rommevaux
Before boarding the Pourquoi Pas?, we visited the island of São Miguel, and in particular Furnace where there are some iron and sulphur rich smokers; terrestrial equivalents of the hydrothermal vents that we will visit at the Lucky Strike site at 1700m depth using the manned submarine Nautile.
Start of the cruise
@Aina Astorch-Cardona
On the 4th of June, 5 members of our team (Valérie C., Christine D., Céline R., Alain C. and Aina A.-C., from left to right) boarded the NO Pourquoi Pas? in Ponta Delgada.
Everyone takes possession of their cabin, which will be one of our main living spaces during these 24 days on board
The other important living space is the dry laboratory, shared by the MIO microbiologists and the GET fluid geochemists
@Aina Astorch-Cardona
@Aina Astorch-Cardona
Sampling of iron-rich mats and associated fluids with the Nautile
@Aina Astorch-Cardona
Before the dive, we prepare the instruments we will need: the biological sampling box for the iron-rich mats (blue star), the titanium syringes for the high-temperature fluids (light green star) and the cannula for sampling the diffuse fluids above the mats (red star) which are stored, after filtration in situ or not, in the bags that Céline R. and Valérie C. are installing on the front of the Nautile. During this time Alain C., who is on watch, is writing down the events that take place in the watch book.
@Aina Astorch-Cardona
@Céline Rommevaux
The Nautile accommodates three people in its 2.10 m diameter titanium sphere: the pilot and co-pilot (Genavir) and the scientist. Each has a window (photo left). The co-pilot sits in a central seat (middle photo) and will manage all the navigation, data acquisition, safety in the sphere, and assist the pilot in some operations. The pilot and the scientist are lying on benches and have access to the navigation, speed and depth indications on the central panel (right photo). The Pilot has under his bench the joysticks for the control of the propulsion units and the manipulation of the arms.
@Céline Rommevaux
@Céline Rommevaux
@Florent Hodel
The boarding of the scientists in the Nautile, here Aina A.-C. (left photo) and Céline R. (middle left photo), is quite a ceremony. As is the retreat of the Nautile to the back deck (right photos) before launching. The three people embark for a dive lasting about 8 hours, including 7 hours of work on the bottom. They will be working on their own project but also on the projects of the other scientists on board.
@Aina Astorch-Cardona
@Céline Rommevaux
@Aina Astorch-Cardona
@Aina Astorch-Cardona
@Aina Astorch-Cardona
Once at the bottom, at a depth of 1700m, we can see hydrothermal vents (Photo on the left), constructions resulting from the precipitation of particles contained in hydrothermal fluids at more than 300°C in contact with the surrounding sea water at 4°C. These hot fluids are sampled with titanium syringes. On the slopes of these hydrothermal constructions, diffuse fluid of temperature ≤150°C can allow the development of iron-rich, rust-coloured microbial mats (middle photo), the main focus of this project. The surrounding fluid just above the mat is collected in 4 x 2L bags with the sampling cannula (Middle photo), for chemical, microbiological and iron isotope analyses. The mat itself is then collected with the clamp of the Nautile's main arm and stored in a biological sampling box. These mats, which are made up of diverse microbial communities including Fe-oxidising bacteria, organic matter (exopolysaccharides, EPS) and iron oxides, are highly volatile and disperse in the water when they are sampled (Photo on the right).
@Aina Astorch-Cardona
@ Damien Roudeau
@Aina Astorch-Cardona
@Aina Astorch-Cardona
Once the Nautile is on board, the conditioning of the different samples begins in the laboratory, in sterile conditions under or near the laminar flow hood. We take care of sub-sampling, filtering and conditioning the fluids from the different bags according to the analyses to be carried out behind them. Then we take care of the biological sampling box containing the iron-rich mats. The box is filled with bottom water that is pumped and filtered (Photo on the left), the filter is preserved because it contains the microorganisms from the sea water and those from the mats that have been resuspended. Then we sub-sample the mat itself into different tubes according to the analyses (DNA, RNA, Proteins, culture) (Second photo from the left), which are then stored at -80°C, except for the culture which is stored at 4°C (Third photo from the left). Pieces of mat are dried on a blotter and then stored in boxes for porosity and mineralogical analysis to identify iron oxides (Right photo)
End of mission and start of work on land
@ Damien Roudeau
This cruise was an opportunity for Aina A.-C., who is doing her thesis at the MIO under the direction of Céline R., and who is working on the dynamics of iron-rich microbial mats, to participate in the collection of samples for her thesis. Above all, it was a great experience to dive in the manned submarine Nautile, to be baptized (Photo on the left) and to obtain a magnificent diploma (Photo on the right)
@Céline Rommevaux