The EMSO-LO site is a certified instrumented site dedicated to long-term observation of the deep ocean. EMSO-LO has a number of specific features that make it a unique deep-sea site, suitable for monitoring long-term environmental and oceanographic changes. It is located in the Mediterranean, in the Ligurian Basin, which is considered to be a miniature ocean, and an area of interest for the characteristics of its water masses and physical and biogeochemical functioning. This site is part of a regional facility (EMSO-Ligure) of the European infrastructure ERIC-EMSO since 2016.
The multidisciplinary instrumentation deployed on these permanent platforms has enabled the acquisition of long-term environmental and biogeochemical data (> 10 years for pressure, temperature, oxygen and currents). The site comprises 3 permanent platforms (an Instrumented Interface Module (MII), a scientific junction box (BJS) and an autonomous instrumented mooring line (ALBATROSS)), dedicated to receiving oceanographic instruments.
In February 2022, a set of innovative instruments were deployed on the site and connected to the BJS platform, enabling the acquisition of environmental and biological data unique at these depths. Unfortunately, in January 2024, a power failure on a node of the LSPM (Provence Méditerranée Submarine Laboratory) suddenly put an end to data acquisition.
In May 2025, we successfully recovered the BJS, BathyBot (remotely operated robot) and its BathyDock.
This operation was carried out in collaboration with Km3NeT and the LSPM from the FOSELEV Marine vessel Castor 02, the SAS (Ship As a Service) research vessel Janus II and its ROV Apache. This operation was funded by CNRS-Ifremer, via theIR EMSO-En. La CNRS-INSU Technical Division (DT INSU) provided essential support for this operation and the intervention of divers from theOSU Pytheas and the MIO has made it possible to secure the recovery of BathyBot. The objects are currently undergoing assessment, maintenance and possible repairs with a view to redeployment in 2026.
At the end of May, the ALBATROSS line recovered last April was successfully redeployed from the NO Tethys II (FOF). It should be noted that the ALBATROSS line has been fitted with new equipment in addition to its 8 microcat (p, T, S, O2) and 6 Aquadopp (Current) dedicated to observing the thermodynamic properties of the north-western Mediterranean, the evolution of the stratification of the water column and the ventilation of waters of Levantine origin and deep waters. At 500m, the line was equipped with a pH sensor, an IODA for measuring oxygen dynamics and a Visu-trap (in collaboration with the LOG and theIMEV) to measure particle flux and acquire images of macroscopic planktonic organisms.
The mooring line consists of 3 stages that can be recovered sequentially. The first stage, comprising the IODA and the Visu-trap, is due to be recovered in a year's time, while the other 2 stages will be recovered in 18-24 months.
Thanks to the DT INSU for this success and to the SAM for their support.
The data are available online.
