The MoMARSAT series of campaigns (https://doi.org/10.18142/130) ensures the annual maintenance of the EMSO-Azores observatory on the Lucky Strike hydrothermal field. This seafloor observatory has been in operation since 2010 and aims to acquire time series ¿10 years on the hydrothermal, tectonic, volcanic processes and ecosystems of an active hydrothermal site of the Mid-Atlantic Ridge. It is part of the European EMSO ERIC network (European Multidisciplinary Seafloor and water column Observatory - http://emso.eu/), supported in France by the EMSO-FR Research Infrastructure (MESR), which is managed by an Ifremer/CNRS collaboration.
The study area is part of Portugal's EEZ and a "Marine Protected Area" (OSPAR).
The LuckyDivMic campaign is this year integrated into the MoMARSAT campaign.

COVID procedure: because of the pandemic, a specific procedure has been put in place for all shippers. The teams were confined to a hotel for one week in Digne, with two PCR tests. Boarding took place in Toulon. During one week, the barrier gestures were applied (no positive). A doctor was embarked exceptionally. Disembarkation also took place in Toulon.

The LuckyDivMic cruise (PI Anne Godfroy, https://doi.org/10.17600/18001345)

Active hydrothermal chimneys are porous mineral structures subjected to a steep physico-chemical gradient that shape their microbial communities. The diversity of microbial communities in hydrothermal vents is well documented but some questions concerning colonization and dynamics of theses microbial communities remain. The objective of the LuckyDivMic project is to carry out sampling of active chimneys at the different sites of the Lucky Strike hydrothermal field to study their microbial diversity (using high throughput sequencing of 16S rRNAs encoding genes and  metagenomes) in order to determine 1)Who are the first colonizers of hydrothermal chimneys, 2) how the microbial populations succeed each to other as the hydrothermal chimney is growing (3) are changes in the structure of these communities directly related to the mineral composition of the chimney and the hydrothermal fluid?

The EMSO-Azores deep sea observatory

EMSO-Açores comprises an observatory infrastructure in the strict sense: a buoy (BOREL) ensuring data transfer to a server on land and communication with the connected instruments, and two sea monitoring nodes (SEAMON) at the bottom, which communicate acoustically with the surface buoy and to which the instruments are connected. The BOREL buoy is also instrumented with a meteorological station, a geodetic GPS, an OTN sensor (2019), and, at a depth of 25 m, a pH/CTD sensor in test phase (2019). Following a break in its mooring line in February 2020, the BOREL buoy was recovered by the Portuguese vessel Archipelago and stored in Horta from February to September. The vessel diverted during the transit between Toulon and Lucky Strike to retrieve the buoy.

The first station (SEAMON West) is deployed in the center of the fossil lava lake characteristic of the hydrothermal field Lucky Strike. It is dedicated to geophysical studies. An OBS (Ocean Bottom Seismometer) and a permanent pressure gauge (JPP) are connected to this station. The second station (SEAMON EAST ) is deployed at the base of the active Eiffel Tower building and allows us to study the interactions between the hydrothermal circulation, the physico-chemical factors and the dynamics of the fauna at the scale of a building. On this station are connected a biological observation module (TEMPO- with an HDTV camera and 4 projectors, temperature, oxygen, dissolved iron sensors), a hydrothermal fluid sampler equipped with a microbial colonizer module (CISICS - not deployed in 2020), a chlorinity/temperature sensor (BARS - not deployed in 2020), a turbidimeter and a dissolved oxygen and temperature sensor. A new chain of thermistors (70m, 100 temperature sensors) was deployed to characterize the Eiffel Tower habitat over one year.

The scientific and technical data acquired by the infrastructure are transmitted 4 times a day to the Ifremer Data Centre in Brest and are available online (http://www.emso-fr.org/fr/EMSO-Azores).

The observing device also includes autonomous instruments, which store the data internally: an autonomous sequential hydrothermal fluid sampler (DEAFS), an array of 4 hydrophones (HYDROCTOPUS) and 4 OBS, 2 permanent pressure gauges (JPP), 36 autonomous hydrothermal fluid and mixing zone temperature probes, 7 autonomous current meters arranged on the bottom, 6 biological and microbiological colonizers, and an oceanographic mooring.
Maintenance operations include the replacement of the BOREL-SEAMON infrastructure and connected instruments, their reconditioning on board, then their redeployment. The backup and redeployment of the autonomous instruments are carried out either during the submarine's inter-dives for the oceanographic mooring, or by dedicated submarine dives for the other sensors and samples.
The geomicrobiological colonizers deployed in 2018 on the Aisics and Capelinhos sites have been recovered and replaced. The Biolucky colonizer associated with DEAFS, deployed on the Montségur site, was also recovered. Iron oxide-rich mats were collected from the North Eiffel Tower and Capelinhos sites to complete the time series initiated in 2016, and new iron-rich mats were collected from the South Isabel, Lac de Lave, Y3 and West Sintra sites to initiate inter-site comparisons. These samples were conditioned on board to perform 16S rRNA screening, metagenomics and metatranscriptomics, identification of iron oxidation proteins, FISH imaging.
Within the framework of the study of the spatial arrangement of faunal assemblages, three 3D reconstructions of active buildings (Eiffel Tower, Capelinhos and Sintra) and various OTUS mosaics were carried out. In parallel, 7 current meters and a chain of thermistors were deployed to characterize the habitat of the Eiffel Tower over one year. The deployment of temperature chains and the Tempo camera module will make it possible to monitor variations in this microenvironment on an infra-annual scale for another year. The numerous Chemini measurements made it possible to characterize the habitat filmed by Tempo, to link the temperature values measured by the thermistor chain with values of sulfur and iron concentrations, and to monitor the evolution of the quadrats set up for the MERCES project. A test of the ELFES prototype (fauna sampler) was carried out and various biological samples were taken (Peltospira smaragdina, small modioles Bathymodiolus azoricus).

Associated projects
In 2019, a specific acquisition program (TUSIG, Financement ISBLUE, B. Ferron et al.) was initiated to characterize small-scale turbulence, map the internal tide and begin geochemical mapping of the hydrothermal plume. This program continued in 2020 with the first deployment of the new MicroRiYo@Sea 3D turbulence observation platform. The 'MicroRiYo' mooring should eventually allow to obtain 200 to 300 vertical profiles of ocean turbulence intensity and water mass mixing. The mooring was launched for the first time on the Momarsat campaign. Complementary CTD/LADCP profiles were carried out nearby to better understand the influence of currents on the mooring.
MoMARSAT missions contribute to WP1, WP2, WP3 and WP4 of the European iAtlantic project. The sampling of shrimp and hydrothermal gastropods will contribute to characterize the contemporary gene flow along the Mid-Atlantic Ridge (WP1). Repeated field visits will allow the acquisition of a large dataset of underwater images and environmental measurements used for spatio-temporal mapping of habitats and communities at building and field scales (WP2, WP3). The data acquired by the observatory will contribute to identify the environmental factors structuring hydrothermal biodiversity, but also to calibrate high-resolution hydrodynamic models.
The FORAVENT project (funding ISBLUE, P.A. Dessandier) aims to characterize the microhabitat of benthic foraminifera faunas through the analysis of the geochemistry of sediments (organic carbon, nitrogen, stable isotopes of organic matter) and pore water (sulphates, sulphides, metals) and to analyze the distribution (density and diversity) of living (phloxine stained) and dead surface faunas in order to determine the ecology of the species in active, peripheral and reference zones. Finally, the measurement of stable isotopes and trace elements on the shells of living benthic foraminifera will allow the calibration of the bio-indicator potential of fluid emissions, potentially applicable to paleo-environmental records. 15 core samples were taken from 7 stations to the east and west of the Eiffel Tower, to the north, south and periphery of Montsegur, near Capelinhos and South Crystal.
Part of the sampling and experimentation program is part of the MERCES project (WP4 leaded by Telmo Morato -IMAR- Pt and Andrew Sweetman -HWU-UK) and ECOREF project (PI M. Matabos, Funding by Equinor) with the specific objective to evaluate the resilience of a modiole assembly and to understand the recolonization processes.
The development of a new observatory for the observation of a cold coral ecosystem in the Bay of Biscay has started in the framework of the MarHa project (LIFE16 IPE FR001). Two deployment tests of this new structure using no lost ballast were carried out during the campaign.
Samples of the crab Segonzacia mesatlantica and the shrimp Mirocaris fortunata are taken every year and supplied to Océanopolis (Brest) as part of the permanent exhibition "Abyssbox".

The MoMARSAT campaign and the EMSO-Azores observatory are thus integrated in the following projects:  
- EMSO ERIC (European Multidisciplinary Seafloor and water column Observatory, www.emso-eu.org/, DG J. Danobeitia) and EMSO link (PI P. Favalli, H2020 Grant agreement No. 731036).
- MERCES (Marine Ecosystem Restoration in Changing European Seas, www.merces-project.eu/, Coordinator Roberto Danovaro Università Politecnica delle Marche, Italy, H2020 grant agreement No. 689518).
- ECOREF (Ecological COnnectivity between active and inactive sites: REcolonization dynamics and Functional links. PI M. Matabos, Funding from EQUINOR).
- iAtlantic (Integrated assessment of the Atlantic Marine Ecosystems in space and time, http://www.iatlantic.eu/, coordinator M. Roberts University of Edinburgh, grant agreement No 818123).
- Abyssbox: Pressurized aquarium presenting to the general public since 2012 crabs and shrimps taken from the Lucky Strike hydrothermal field at Océanopolis Brest. PI D. Barthélémy.
- ISBLUE Interdisciplinary graduate school for the blue planet (ANR-17-EURE-0015). PI A.M. Tréguier https://www.isblue.fr/
- MarHa - Marine Habitat project - PI J. Delavenne OFB, LIFE16 IPE FR001. PI Julie Tourolle for the Ifremer contribution.

The data acquired during the campaign are available online :
- data acquired by the infrastructure via the portal - http://www.emso-fr.org/fr/EMSO-Azores.
- the video data acquired by the ROV Victor on the Video Marine Sciences portal - http://video.ifremer.fr/.
- campaign and dive reports on the campaign catalog portal https://www.flotteoceanographique.fr.