|This cruise is part of the set MOMARSAT : MONITORING THE MID ATLANTIC RIDGE
|Pourquoi pas ?
|11/06/2019 - 03/07/2019
|SARRADIN Pierre-Marie , LEGRAND Julien
ETUDES DES ECOSYSTEMES PROFONDS
IFREMER Centre de Bretagne
ZI Pointe du diable
+33 (0)2 22.214.171.124
The Momarsat 2019 cruise performs the yearly maintenance of the EMSO-Azores observatory at Lucky Strike (Mid-Atlantic Ridge). EMSO-Azores is a fixed-point buoyed observatory with a multidisciplinary approach (from geophysics and physical oceanography to ecology and microbiology).The observatory focuses on two main questions: What are the feedbacks between volcanism, deformation, seismicity, and hydrothermalism at a slow spreading mid-ocean ridge and how does the hydrothermal ecosystem couple with these sub-seabed processes? The studied area is part of a Marine Protected Area in the Portuguese EEZ.
It is a component of the EMSO European Research Infrastructure Consortium, which coordinates observatory regional facilities in European seas (http://emso.eu).
The uncabled observing system was first deployed in 2010 in the Lucky Strike hydrothermal vent field (Mid Atlantic Ridge) at 1700 m depth. It comprises two Sea Monitoring Nodes (SEAMON) providing the energy, controlling the sensors, archiving and transmitting the data. The first node is deployed on the Lucky Strike fossil lava lake and measures the seismic activity (1 OBS) and the vertical deformation of the sea floor (2 pressure gauges). The second one is deployed at the base of the Tour Eiffel active edifice. It allows the study of the variability of a mussel assemblage and its environment (HD camera and chemical sensors, thermistor string), the microbial colonization and the chlorinity of an active vents (microbial colonization module CISICS and BARS sensor) . The two nodes are acoustically linked to a surface relay instrumented buoy (BOREL), ensuring satellite communication to the land base station in Brest -France. The buoy is also instrumented with a meteorological station, a geodetic GPS, an OTN sensor and a pH/CTD sensor at 25m below the surface.
Data are archived, published with a doi and are available on the EMSO-Azores web page: http://www.emso-fr.org/EMSO-Azores.
In addition, the observatory setup comprises several sets of autonomous instruments, whose data are collected during the yearly maintenance cruises. The autonomous instruments deployed in the area comprises 4 OBS, 2 pressure gauges, a physical oceanography mooring near the vent field, an array of temperature probes distributed in hot and diffuse vents, 6 biological or microbiological colonisation devices, 3 bottom currentmeters, a localized micro seismicity array (HYDROCTOPUS - seabed array of 4 hydrophones) and a prototype of sequential hot fluid sampler (DEAFS).
A complementary site studies program is implemented during the cruises and contributes to increase the set of accessible parameters (fluid sampling, ecological studies, survey of active and inactive areas, in situ experimentations¿) and to extend the spatial coverage of the study. An experiment to study the restoration of the bathymodiolus azoricus modiole assemblages after disturbance was initiated in 2017. Specimens of the Segonzacia mesatlantica crab and the Mirocaris fortunata shrimp are collected, kept alive and transferred to Brest at Océanopolis for the public exhibition "Abyss box" started in 2012 in collaboration between Oceanopolis, Univ. Paris Sorbonne (UPMC), Ifremer.
This year, a specific programm was initiated (TUSIG, Funded by ISBLUE) to characterize the small scale turbulence of the water column, to map the internal tide and the geochemical composition of the hydrothermal plume. CTD casts, associated to water samples and VMP (Vertical Micro^profiler) profiles were done during the cruise,
The observatory is maintained every year during the Momarsat cruises (https://doi.org/10.18142/130). All the components of the system are recovered, serviced on board and redeployed using the HOV Nautile this year.
In addition, this year, the Plouarnautes programwas set up, to create a partnership between elementary school classes and Ifremer, focused on the discovery and study of deep ecosystems, including hydrothermal vents. This new project builds on the existing resources developed in the framework of the citizen science project "Deep Sea Spy", which invites users to annotate the images acquired by sea-bottom observatories. This partnership was concretized by the creation and maintenance of a blog fed by students and scientists on board during the campaign (https://www.deepseaspy.com/Plouarnautes). This first edition of the project involved two schools this year: the school Mouez ar Mor in Ploumoguer with 5 classes corresponding to 120 students from kindergarten to CM2 and Saint Pierre school in Plougastel-Daoulas with 1 class of CP of 24 students.
The MoMARSAT and the EMSO-Azores deep sea observatory are linked to the following projects :
The data acquired during the crusie are available on line :
- data acquired by the EMSO-Azores infrastructure : http://www.emso-fr.org/fr/EMSO-Azores.
- Video sequences recorded during the Nautile's dive : http://video.ifremer.fr/
- The cruise reports : https://campagnes.flotteoceanographique.fr/