<p style="text-align:justify">The main objective of the observing system MOOSE is to monitor the long-term evolution of the north-western Mediterranean Sea (over more than 10 years) in the context of climate change and anthropogenic pressure in order to detect and identify the trend and environmental anomalies of the marine ecosystem. The MOOSE network aims to establish an integrated and multidisciplinary system in the Mediterranean Sea in accordance with the objectives of the national MISTRALS program (HyMeX, MeRMEX and ChARMeX). The MOOSE system is supported by national institutes (CNRS-INSU, French Ministry of Higher Education and Research) and involved different partners (Universities, IFREMER, Meteo France).</p> <p style="text-align:justify">The MOOSE network includes "multi-scale" measurement capabilities to accurately document the broad spectrum of hydrodynamic processes already identified (large scale eddies, mesoscale eddies, biogeochemical provinces). High temporal resolution measurements are obtained from fixed observatories (moorings, buoys) but their spatial distribution remains insufficient. Spatial variability is of the same order as temporal variability and understanding the evolution of this basin as a whole implies being able to dissociate both. Synergy with other strategies (ships, floats, gliders) is essential for the establishment of an observation network in such a system. To address the issues identified by MOOSE, two key areas of the north-western basin have been identified:</p> <ul> <li style="text-align:justify">The central and western part of the Ligurian Sea, which constitutes a homogeneous system isolated from direct coastal inputs by rivers and where atmospheric inputs are predominant (DYFAMED and ANTARES). It is also one of the entrance passages of the Intermediate Levantine Water (LIW) in the north-western Mediterranean basin.</li> <li style="text-align:justify">The central area of the Gulf of Lion where winter cooling leads to vertical mixing over 2000 m and sometimes to the bottom. The LION site (42°N 5°E) is ideal for studying the variability of winter convection to better understand mixing processes and dense water formation. It also characterizes the variability of the deep particle flow.</li> </ul> <p style="text-align:justify">Currently, fixed observation at these sites is carried out by six moorings:</p> <ul> <li style="text-align:justify">The Planier and Lacaze-Duthiers moorings composed of sediment traps and T/S sensors and current meters, for dense water cascading and particle export studies. These moorings have been set up since 1994 and managed by CEFREM.</li> <li style="text-align:justify">The LION mooring, consisting of a large number of T/S sensors, current meters, and two oxygen sensors, is in the Gulf of Lion convection zone. It has been deployed since 2007, and is managed by CEFREM and LOCEAN. A sediment trap near the bottom has also been present for 2 years in this area (LIONCEAU mooring). The latter will be integrated into the LION mooring in 2019.</li> <li style="text-align:justify">The ANTARES mooring is located in the North Current off Toulon and equipped with T/S sensors, current meters and oxygen sensors to quantify the bacteria activity and organic matter remineralization process in a deep marine environment. It exists since 2004, it is managed by the M.I.O. and the CPPM (Marseille). This mooring is part of the ERIC EMSO since 2017.</li> <li style="text-align:justify">The DYFAMED mooring, in the Ligurian Sea, equipped with sediment traps, T/S sensors, current meters and oxygen sensors to monitor the evolution of the water column, the impact of atmospheric dust deposition and marine particles export to deep waters. It exists since 1988, it is currently managed by the Oceanological Observatory of Villefranche-sur-Mer. This mooring is part of the ERIC EMSO since 2017.

Small pelagic fish are both the keystone species of the ecosystem because of the central position they hold in the food chain and represent highly significant economic stakes for fisheries since they make up the majority of landings in the French Mediterranean (approximately 50% of catches for sardines and anchovies; Demaneche et al. 2009). So, to assess stocks and propose appropriate management methods, it is important to have both good knowledge about these species and independent fisheries data. Ifremer's fisheries science laboratory in Sète has monitored these populations since the 1990s. In 2002, the EU asked Member States to formalize certain operations by contract, in this context, the PELMED cruise was part of the extended contractual programme for biomass assessment (DCF). Therefore, each year France is obliged to assess the biomass of small pelagic species in the Mediterranean, in order to determine the stocks' status and propose management measures. These assessments are carried out in the framework of the general fisheries commission for the Mediterranean (CGPM). Since numerous countries had begun monitoring these species using acoustic methods, the MEDIAS (MEDIterannean Acoustic Surveys) scientific group was created in 2008 with the objective of standardizing the protocols. Finally, national management plans for Gulf of Lion fisheries were set up in 2014 (particularly for pelagic trawlers and purse seines) with scientific objectives touching on the biomass of small pelagics. The PELMED cruise, whose main aim is to directly assess the small pelagics biomass, is conducted therefore in a clearly institutional framework (national, European and Mediterranean). However, the scientific stakes remain just as important. Since 2008, a special situation has been observed in the Gulf of Lion, where the biomasses of sardines and anchovies (and even mackerel) have decreased synchronously. Even more unexpectedly, although the recruitment rates observed over the past few years in the species are particularly high, the populations don't seem to be growing back and their biomass is continuing to drop. This is particularly surprising in a marine ecosystem where recruitment is generally considered to be the determining factor of population dynamics for species with a short life span. The collection of biological parameters on species of small pelagics done during the previous PELMED cruises made it possible to highlight significant demographic changes (loss of large age classes, decrease in size, poorer body condition) which seem to suggest "bottom-up" population control. Therefore, the ecosystem-based nature of the PELMED cruises (from physical parameters to top predators, not to mention phyto- and zooplankton and fodder fish) appears to be crucial in understanding the dynamics of these populations. It was decided this year to stop prospecting the Catalan Sea, in order to extend the spatial coverage to the east of the Gulf in the PACA region (from Marseille to Nice). Since the narrowness of the shelf in this zone does not allow for prospecting along "classic" legs, the objective will be to validate a prospection method which is adapted to the area.

Investigations at the dumpsite for low-level radioactive waste at the Iberian Deep Sea Plain

This cruise was completed as part of the United Kingdom Natural Environment Research Council (NERC) funded RAPID Programme to monitor the Atlantic Meridional Overturning Circulation at 26.5ºN. The primary purpose was to service the Eastern Boundary and Mid-Atlantic ridge sections of the 26.5ºN mooring array. The Rapid-MOC array of moorings was deployed across the Atlantic to set up a pre-operational prototype system to continuously observe the Atlantic Meridional Overturning Circulation (MOC). This array will be further refined and refurbished during subsequent years as part of the Rapid-WATCH programme. The instrumentation deployed on the array consists of a variety of CTD loggers, current meters, bottom pressure recorders, and Inverted Echo-sounders, which, combined with time series measurements of the Florida Current and wind stress estimates, can be used to determine the strength and structure of the MOC.

Hydrography and physical oceanography cruise for the French Navy's hydrographic and oceanographic service (SHOM).

Studying the role played by formation of deep water in the chemical composition and budgets of matter in the Mediterranean. Understanding the relationships between the way plankton food webs are organized and the hydrodynamic structures. The related project is MISTRALS - MerMEX.

Charter cruise with the objective of validating the performance of SERCEL equipment, i.e. evaluation of different seismic devices and validating this equipment.

<p style="text-align:justify">SHOM cruise with implementation of the MVP.</p>

SHOM cruise between Falmouth and Brest

The cruise D361 forms part of a study entitled 'Physical and chemical forcing of diazotrophy in the (sub)-tropical Atlantic Ocean'. The study is investigating the potential influence of iron and phosphorus availability on nitrogen fixation in regions of the tropical Atlantic Ocean. The cruise also undertakes deep trace metal clean CTD casts as part of the International GEOTRACES programme. The purpose of the cruise therefore is to undertake measurements of dissolved and particulate iron and phosporpus availability, their spatial and temporal variations, and their impact on diazotrophy in the surface ocean. Aim: To quantify the supply and determine the biogeochemical cycling of Fe and other nutrients, and relate this to N2 fixation, diazotroph species distribution and N* fields. 1. Quantify the distribution of nutrients and trace metals: Quantify surface water and water column distributions of dissolved inorganic/organic N, P, Fe, and DAl, DMn and particulate P, N, Fe, Al, Mn. 2. Quantify the rate of Fe, Al, Mn, P and N supply to surface waters: Assess the source fluxes of the key elements for diazotrophs and source tracers to the surface ocean from atmospheric deposition and internal transport via diapycnal mixing and lateral advection. 3. Identify the source of subsurface Fe enrichment: Identify whether Fe-rich subsurface waters of the tropical North Atlantic thermocline originate from the atmosphere or the shelf using Fe distributions and Al, Mn, and O2 source tracers. 4. Quantify the diazotrophic response to Fe, phosphate, DOP supply: Relate the spatial distributions of inorganic Fe and organically complexed Fe, and phosphate and DOP to diazotrophy. The specific uptake of Fe, phosphate and DOP by the whole microbial community and Trichodesmium will be assessed by shipboard incubations, radiotracer techniques and enzyme bioassays. In addition, we will identify the connection between N2 fixation rates and diazotroph community structure, by comparing size fractionated 15N2-derived rates of N2 fixation (Fig. 1) with abundance and diversity of diazotrophs using nifH phylogeny. Objective 5: Investigate how the large scale transport pathways of Fe and P influence the N* distribution: Use fine-scale isopycnic model to reveal the large-scale transport pathways of Fe and P in the (S)-T Atlantic, and their effect on the N* distribution.