Bay Of Marseille Research Articles

Occurrence of perfluoroalkyl substances in the Bay of Marseille (NW Mediterranean Sea) and the Rhône River.

Four perfluoroalkyl substances (PFAS) were analyzed in 62 duplicate surface water samples from the Rhône River and Marseille Bay (France; NW Mediterranean Sea). Perfluorooctane sulfonate (PFOS) was detected in all samples and exceeded the European Environmental Quality Standard (EQS) values in over 80% of the cases. The most contaminated samples were from the Rhône River (up to 200 ng L-1 ∑4 PFAS), as well as those collected near a wastewater treatment plant outlet in Marseille Bay (up to 9 ng L-1 ∑4 PFAS). While PFOS was the predominant PFAS in Marseille Bay, remarkably high concentrations of perfluorohexanoic acid (PFHxA) were measured in the Rhône River (8-193 ng L-1). The relative abundances of individual compounds differed thus significantly between the Rhône River and Marseille Bay, indicating different sources. A simulation made with the MARS3D model showed that PFOS inputs from the Rhône River can enter Marseille Bay at levels > EQS.

Seasonal variation in biochemical and energy content of size-fractionated zooplankton in the Bay of Marseille (North-Western Mediterranean Sea)

Zooplankton plays a prominent role in marine pelagic food webs, but its contribution to organic matter transfer from phytoplankton to upper level consumers is modulated by size and specific composition. The biochemical composition (protein, carbohydrate and lipid concentrations) and energy content of size- and group-fractionated zooplankton were analyzed in the North-Western Mediterranean Sea (Marseille) over 18 months. Proteins were the most abundant biochemical compounds in all size classes and zooplankton groups, and provided the largest part of the energy content. The medium (200–1000 μm) size classes, mainly composed of copepods, crustacean larvae and eggs, presented a higher protein and energy content than both the smallest (80–200 μm) size class, mainly composed of phytoplankton, and the largest (>1000 μm) size classes, composed of siphonophores, salps and chaetognaths. Strong and similar seasonal variations in zooplankton biochemical composition were observed in all size classes, with higher energy content associated with cold oxygen- and nutrient-rich waters in spring 2017 and winter 2018. Thus, the biochemical composition of plankton size classes and groups differed and varied seasonally along with environmental parameters. This novel approach for North-Western Mediterranean Sea may be further related with studies on the energy and nutrient transfer into pelagic food webs and contribute to understanding of how zooplanktivorous fish feeding preferences may be related to the quality of zooplankton prey.

From seascape ecology to population genomics and back. Spatial and ecological differentiation among cryptic species of the red algae Lithophyllum stictiforme/L. cabiochiae, main bioconstructors of coralligenous habitats

Ecosystem engineering species alter the physical structure of their environment and can create or modify habitats, having a massive impact on local biodiversity. Coralligenous reefs are highly diverse habitats endemic to the Mediterranean Sea built by calcareous benthic organisms among which Crustose Coralline Algae are the main engineering species. We analyzed the diversity of Lithophyllum stictiforme or L. cabiochiae in coralligenous habitats combining a multiple barcode and a population genomics approach with seascape features. Population genomics allowed disentangling pure spatial effects from environmental effects. We found that these taxa form a complex of eight highly divergent cryptic species that are easily identifiable using classic barcode markers (psbA, LSU, COI). Three factors have a significant effect on the relative abundances of these cryptic species: the location along the French Mediterranean coast, depth and Photosynthetic Active Radiation (PAR). The analysis of around 5000 SNPs for the most abundant species revealed genetic differentiation among localities in the Bay of Marseille but no differentiation between depths within locality. Thus, the effect of depth and PAR on cryptic species communities is not a consequence of restricted connectivity but rather due to differential settlement or survival among cryptic species. This differential is more likely driven by irradiance levels rather than by pressure or temperature. Both the genetic and species diversity patterns are congruent with the main patterns of currents in the Bay. Ecological differentiation among these engineering cryptic species, sensitive to ocean warming and acidification, could have important consequences on the diversity and structure of the coralligenous communities.

The Bay of Marseille, Viewed from L'Estaque, 2010

The fishing village of L'Estaque is a few kilometers northwest of Marseille. At the beginning of the 20th century, L'Estaque was the cradle of modern painting. Artists continued to be drawn there for 6 decades, between 1860 and 1920. Impressionism, Fauvism, and Cubism were all developed by artists who resided in L'Estaque. Paul Cezanne and Georges Braque are the best known—Cezanne for “The Bay of Marseille, Seen from L'Estaque” (c. 1885) (1 …

One-Single Extraction Procedure for the Simultaneous Determination of a Wide Range of Polar and Nonpolar Organic Contaminants in Seawater

A rapid analytical method including one-single solid-phase extraction procedure followed by gas and liquid chromatography coupled with high resolution mass spectrometry detection (GC–MS and LC–HRMS respectively) was developed for the quantification of 40 polar and nonpolar organic compounds (1.6 < log Kow < 9.5) in seawater including both legacy and emerging contaminants, with a focus on the most common plastic organic additives. This new method allowed for the analyses of nine organophosphate esters (OPEs), seven phthalates (PAEs), six bisphenols (BPs), five perfluorinated compounds (PFCs), and thirteen legacy organochorinated compounds (OCs, including polychlorobiphenyles and pesticides) with recoveries in the ranges of 57–124 % for OPEs, 52–163 % for PAEs, 64–118 % for BPs, 63–124 % for PFCs, and 40–95 % for OCs. As a result of i) strict cleanup protocols, ii) material and solvent selection, and iii) the use of an ISO 6 cleanroom for sample treatment, the procedural blank levels were always lower than 5 ng L−1, even for the most abundant and ubiquitous compounds like tris-(2-chloro, 1-methylethyl) phosphate (TCPP) and diethylhexyl phthalate (DEHP). The quantification limits were in the ranges of 0.03–0.75 ng L−1 for OPEs, 0.03–0.25 ng L−1 for PAEs, 0.1–5 ng L−1 for BPs, 0.1–8 ng L−1 for PFCs, and 0.02–1.1 ng L−1 for OCs, matching seawater analysis requirements. Dissolved water phase samples collected in Marseille Bay (NW Mediterranean Sea) were analyzed using the developed method reveling the concentration of PAEs up to 140 ng L−1 (DEHP) and that of OCs up to 70 ng L−1 (α-endosulfan). For the first time, we also provided the concentrations of OPEs (TCPP up to 450 ng L−1), BPs (bisphenol S up to 123 ng L−1), and PFCs (PFOS up to 5 ng L−1) in this area. A sampling station close to the municipal waste water treatment plant outfall exhibited the highest concentration levels for all compounds.

Distribution of phthalates in Marseille Bay (NW Mediterranean Sea)

Phthalic Acid Esters (PAEs) are a group of emerging organic contaminants that have become a serious issue because of their ubiquitous presence and hazardous impact on the marine environment worldwide. Seawater samples were collected monthly from December 2013 to November 2014 in the northwestern Mediterranean Sea (Marseille Bay). The samples were analyzed for dissolved organic carbon (DOC) as well as the molecular distribution of dissolved PAEs by using solid phase extraction followed by gas chromatography and mass spectrometry (GC/MS) analyses. The results demonstrated the occurrence of six PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-isobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), benzylbutyl phthalate (BzBP) and diethylhexyl phthalate (DEHP), with total concentrations ranging from 130 to 1330ngL−1 (av. 522ngL−1). In Marseille Bay, the highest concentrations were detected in the bottom water from June to November 2014 and in the whole water column during the winter mixing period. This result suggests that resuspension of PAE-rich sediment, in relation to the accumulation of plastic debris above the seabed, or the higher degradation rate in the upper layer of the water column, plays a significant role in the PAE dynamics in coastal water. DEHP was the most abundant PAE in all of the surface samples and the summer bottom samples, followed by DiBP and DnBP, which also represent the largest fractions in the other bottom samples.

Occurrence of microplastics in surface waters of the Gulf of Lion (NW Mediterranean Sea)

Between 2014 and 2016 a total of 43 microplastic samples were collected at six sampling stations in the eastern section of the Gulf of Lion (located in the northwestern Mediterranean Sea), as well as upstream of the Rhône River. Microplastics were found in every sample with highly variable concentrations and masses. Concentrations ranged from 6 · 103 items km−2 to 1 · 106 items km−2 (with an average of 112 · 103 items km−2), and mass ranged from 0.30 g km−2 to 1018 g km−2 DW (mean 61.92 ± 178.03 g km−2). The samples with the highest and lowest microplastic count originate both from the Bay of Marseille. For the Bay of Marseille, it is estimated that the total microplastic load consist of 519 · 103 –101 · 106 items weighing 0.07–118 kg. Estimations for daily microplastic transport by the Northern Current and the Rhône River, two important hydrologic features of the northwestern Mediterranean Sea, range from 0.18 to 86.46 t and from 0.20 to 21.32 kg, respectively. Particles < 1 mm2 clearly dominated sampling stations in the Northern Current, the Rhône River and its plume (52, 53 and 61%, respectively), suggesting a long exposure time in the environment. Items between 1 mm2 and 5 mm2 in size were the most abundant microplastics in Marseille Bay (55%), which suggests coastal pollution sources or the removal of smaller particles from surface waters e.g. by ballasting owing to the presence of epibionts.

Occurrence of phthalate acid esters (PAEs) in the northwestern Mediterranean Sea and the Rhone River

Phthalate acid esters (PAEs) which are mainly anthropogenic molecules with endocrine disrupting effects in animals and humans, have been detected in terrestrial and aquatic environments. However, little is known about their distribution in the Mediterranean Sea, mainly because of analytical difficulties and the high possibility of ambient sample contamination. Here, we report the optimization of an existing protocol for the determination of PAEs in seawater and freshwater samples, as well as the first estimation of the source and distribution of phthalates acid esters (PAEs) in coastal waters from the NW Mediterranean Sea. By passing 1L of sample through glass cartridges packed with 200mg of Oasis HLB and eluted with 6mL of ethyl acetate followed by gas chromatography and mass spectrometry (GC/MS) analyses, the recoveries for DMP, DEP, DPP, DiBP, DnBP, BzBP, DEHP and DnOP were 101, 98, 115, 110, 99, 98, 103 and 95%, respectively, with acceptable blank values (below 0.4–4.0% of the masses measured in different seawater samples). By using this method, we detected PAEs in the Marseilles coastal area, offshore (2000m depth) and in the Rhone River with total concentrations ranging from 75.3ng/L offshore in surface water to 1207.1ng/L a few meters above the bottom of the Marseilles Bay. High concentrations were also observed in deep waters offshore (310.2ng/L) as well as in the Rhone River (615.1ng/L). These results suggest that Marseilles urban area, Rhone River and sediment are potential sources of PAEs in the areas studied.In the Rhone River, DEHP was the most abundant PAE (66.1%) followed by DiBP (20.5%) and DnBP (6.6%), whereas a gradual change was observed in the plume of the river with increasing salinity. In the Marseilles Bay, DiBP was the most abundant PAE at the surface (47.3% of total PAEs) followed by DEHP (22.7%) and DnBP (19.1%), whereas DnBP was predominant (38.6%) a few meters above the bottom. By contrast, DEHP was the dominant species in the first 50m (66.9–76.7%) offshore followed by DnBP (10.9–15.2%), whereas DnBP was the most abundant (57.0–72.6%) followed by DEHP (20.1–33.1%) in the deepest waters. This study suggests that in addition to direct PAEs injection in marine waters, different processes regulate PAE distribution in Mediterranean Sea including photochemical oxidation reactions, bacterial degradation and possible diffusion following release from marine litter near the bottom.

Connectivity of Populations of the Seaweed Cystoseira amentacea within the Bay of Marseille (Mediterranean Sea): Genetic Structure and Hydrodynamic Connections

Connectivity of populations of the seaweed Cystoseira amentacea within the Bay of Marseille (Mediterranean Sea): genetic structure and hydrodynamic connections

Pre-Pliocene tectonostratigraphic framework of the Provence continental shelf (eastern Gulf of Lion, SE France)

AbstractThe seaward extension of onshore formations and structures were previously almost unknown in Provence. The interpretation of 2D high-resolution marine seismic profiles together with the integration of sea-bottom rock samples provides new insights into the stratigraphic, structural and paleogeographic framework of pre-Messinian Salinity Crisis (MSC) deposits of the Provence continental shelf. Seven post-Jurassic seismic units have been identified on seismic profiles, mapped throughout the offshore Provence area and correlated with the onshore series. The studied marine surface and sub-surface database provided new insights into the mid and late Cretaceous paleogeography and structural framework as well as into the syn- and post-rift deformation in Provence. Thick (up to 2000 m) Aptian-Albian series whose deposition is controlled by E-W-trending faults are evidenced offshore. The occurrence and location of the Upper Cretaceous South-Provence basin is confirmed by the thick (up to 1500 m) basinal series downlaping the Aptian-Albian unit. This basin was fed in terrigenous sediments by a southern massif (“Massif Méridional”) whose present-day relict is the Paleozoic basement and its sedimentary cover from the Sicié imbricate. In the bay of Marseille, thick syn-rift (Rupelian to Aquitanian) deposition occurred (&amp;gt;1000 m). During the rifting phase, syn-sedimentary deformations consist of dominant N040 to N060 sub-vertical faults with a normal component and N050 drag-synclines and anticlines. The syn-rift and early post-rift units (Rupelian to early Burdigalian) are deformed and form a set of E-W-trending en echelon folds that may result from sinistral strike-slip reactivation of N040 to N060 normal faults during a N-S compressive phase of early-to-mid Burdigalian age (18–20 Ma). Finally, minor fault reactivation and local folding affect post-rift deposits within a N160-trending corridor localized south of La Couronne, and could result from a later, post-Burdigalian and pre-Pliocene compressive phase.

Feeding strategies of co-occurring suspension feeders in an oligotrophic environment

Suspension-feeders predominate in the vast majority of the coastal marine benthic ecosystems, with several species co-occurring at low spatial scale. Understanding how these species cope with competition for trophic resources has been the core of numerous studies, mostly in coastal shallow systems where food supplies are diverse and abundant. Oligotrophic systems have received less attention. The aim of the present study was thus to investigate the trophic relationships established between 9 suspension feeders collected in an oligotrophic zone (Bay of Marseille, French Mediterranean). Species displayed similar isotopic ratios, consistently with the use of one main source, identified as nanophytoplankton and diazotrophic bacteria as the δ15N values were low, in contrast to interspecific differences generally observed. The seasonal variations of the isotopic ratios and isotopic niche indices were explained by differential sorting abilities, higher for bivalves than for ascidians and the polychaete Chaetopterus variopedatus. The present results demonstrate that resource availability in oligotrophic systems is a major driver of trophic competition. It precludes a general conclusion about suspension feeders trophic patterns drawn exclusively from highly productive systems, and stresses the need for an extensive assessment of those patterns in a vast range of ecosystems.

The red coral (Corallium rubrum) transcriptome: a new resource for population genetics and local adaptation studies.

The question of species survival and evolution in heterogeneous environments has long been a subject for study. Indeed, it is often difficult to identify the molecular basis of adaptation to contrasted environments, and nongenetic effects increase the difficulty to disentangle fixed effects, such as genetic adaptation, from variable effects, such as individual phenotypic plasticity, in adaptation. Nevertheless, this question is also of great importance for understanding the evolution of species in a context of climate change. The red coral (Corallium rubrum) lives in the Mediterranean Sea, where at depths ranging from 5 to 600m, it meets very contrasted thermal conditions. The shallowest populations of this species suffered from mortality events linked with thermal anomalies that have highlighted thermotolerance differences between individuals. We provide here a new transcriptomic resource, as well as candidate markers for the study of local adaptation. We sequenced the transcriptome of six individuals from 5m and six individuals from 40m depth at the same site of the Marseilles bay, after a period of common garden acclimatization. We found differential expression maintained between the two depths even after common garden acclimatization, and we analysed the polymorphism pattern of these samples. We highlighted contigs potentially implicated in the response to thermal stress, which could be good candidates for the study of thermal adaptation for the red coral. Some of these genes are also involved in the response to thermal stress in other corals. Our method enables the identification of candidate loci of local adaptation useful for other nonmodel organisms.

Local scale connectivity in the cave-dwelling brooding fish Apogon imberbis

A lower degree of population connectivity is generally expected for species living in a naturally fragmented habitat than for species living in a continuum of suitable environment. Due to clear-cut environmental conditions with the surrounding littoral zone, underwater marine caves of the Mediterranean Sea constitute a good model to explore the effect of habitat discontinuity on the population structure of their inhabitants. With this goal, the genetic population structure of Apogon imberbis, a mouth-brooding teleost, was explored using the mitochondrial cytochrome b gene and 7 nuclear microsatellite loci from 164 fishes sampled at the micro-scale (ca. 40km) of the Marseille area (Bay of Marseille and Calanques coast, in NW Mediterranean). Both marker types indicated a low level of genetic structure within the studied area. We propose that each suitable crack and cavity is used as a stepping-stone habitat between disconnected large cave-habitats. This, together with larval dispersal, ensures enough gene flow between caves to homogenize the genetic pattern at microscale while isolation by distance and by open waters could explain the small structure observed. The present study indicates that the effect of natural fragmentation in connectivity disruption can largely be counter-balanced by life history traits and overlooked details in habitat preferences.

PCB concentrations in plankton size classes, a temporal study in Marseille Bay, Western Mediterranean Sea

PCB levels in plankton were investigated in the Bay of Marseille, Western Mediterranean Sea, between September 2010 and October 2011. Concentrations of PCB congeners (CB 18, CB 52, CB 101, CB 118, CB 138, CB 153, CB 180) were determined in three plankton size-classes (60–200, 200–500 and 500–1000μm) together with different parameters: chlorophyll content, plankton dry-weight biomass, carbon and nitrogen stable isotope ratios and plankton-community structure. The ∑PCB7 concentrations ranged between 14.2 and 88.1ngg−1d.w., for all size classes and all sampling periods. The results do not show the biomass dilution effect and indicate moderate but significant biomagnification with plankton trophic position estimated by δ15N signatures. Equilibrium with water phase may notably contribute in controlling the PCB levels in the plankton. More generally, presented results imply that PCB accumulation in the plankton is an effect of abiotic and trophic complex interactions in the Bay of Marseille.

Intrusion of Rhone River diluted water into the Bay of Marseille: Generation processes and impacts on ecosystem functioning

AbstractThe Rhone River provides the largest inputs of terrestrial freshwater and nutrients into the Mediterranean Sea. The Rhone River diluted water intrusions into the Bay of Marseille were investigated, examining their physical generation processes and associated biogeochemical impact by using in situ observations, remote sensing data, and a three‐dimensional physical/biogeochemical coupled model. During our study period from 2007 to 2011, Rhone River intrusions occurred on average 7.6 times per year and affected more frequently the northern part of the bay. A classification of intrusion events in three categories is proposed (short lived, big, and small) as a function of their duration and spatial extent. The intrusions appeared to be driven by: (i) wind forcing, (ii) the presence of a mesoscale eddy, (iii) the Rhone River discharge volume, and (iv) the variation in thermocline depth. Typically, a combination of these favorable factors was necessary to induce an intrusion. An intrusion strongly impacts the biogeochemical functioning of the Bay of Marseille by bringing large quantities of nutrients into the bay. Mass balances were computed allowing us to quantify this impact on the Bay of Marseille. The results show that the ecological impact depends very much on the type of intrusion, with big intrusions having the highest impact.

An annual survey of bacterial production, respiration and ectoenzyme activity in coastal NW Mediterranean waters: temperature and resource controls.

We simultaneously measured bacterial production (BP), bacterial respiration (BR), alkaline phosphatase activity (phos) and ectoaminopeptidase activity (prot) in relation to biogeochemical parameters, nutritive resources and in situ temperature over a 1-year survey at the long-term observatory the SOLEMIO station (Marseille bay, NW Mediterranean Sea). Despite its proximity to the coast, oligotrophic conditions prevailed at this station (yearly mean of Chl a = 0.43 μg dm(-3), NO3 = 0.55 μmol dm(-3) and PO4 = 0.04 μmol dm(-3)). Episodic meteorological events (dominant winds, inputs from the Rhone River) induced rapid oscillations (within 15 days) in temperature and sometimes salinity that resulted in rapid changes in phytoplankton succession and a high variability in C/P ratios within the particulate and dissolved organic matter. Throughout the year, BP ranged from 0.01 to 0.82 μg C dm-(3) h-(1) and bacterial growth efficiency varied from 1 to 39%, with higher values in summer. Enrichment experiments showed that BP was limited most of the year by phosphorus availability (except in winter). A significant positive correlation was found between in situ temperature, BP, BR and phos. Finally, we found that temperature and phosphate availability were the main factors driving heterotrophic bacterial activity and thus play a fundamental role in carbon fluxes within the marine ecosystem.

Development of a 3D Coupled Physical-Biogeochemical Model for the Marseille Coastal Area (NW Mediterranean Sea): What Complexity Is Required in the Coastal Zone?

Terrestrial inputs (natural and anthropogenic) from rivers, the atmosphere and physical processes strongly impact the functioning of coastal pelagic ecosystems. The objective of this study was to develop a tool for the examination of these impacts on the Marseille coastal area, which experiences inputs from the Rhone River and high rates of atmospheric deposition. Therefore, a new 3D coupled physical/biogeochemical model was developed. Two versions of the biogeochemical model were tested, one model considering only the carbon (C) and nitrogen (N) cycles and a second model that also considers the phosphorus (P) cycle. Realistic simulations were performed for a period of 5 years (2007–2011). The model accuracy assessment showed that both versions of the model were able of capturing the seasonal changes and spatial characteristics of the ecosystem. The model also reproduced upwelling events and the intrusion of Rhone River water into the Bay of Marseille well. Those processes appeared to greatly impact this coastal oligotrophic area because they induced strong increases in chlorophyll-a concentrations in the surface layer. The model with the C, N and P cycles better reproduced the chlorophyll-a concentrations at the surface than did the model without the P cycle, especially for the Rhone River water. Nevertheless, the chlorophyll-a concentrations at depth were better represented by the model without the P cycle. Therefore, the complexity of the biogeochemical model introduced errors into the model results, but it also improved model results during specific events. Finally, this study suggested that in coastal oligotrophic areas, improvements in the description and quantification of the hydrodynamics and the terrestrial inputs should be preferred over increasing the complexity of the biogeochemical model.

Seasonal variation of stable isotope ratios of size-fractionated zooplankton in the Bay of Marseille (NW Mediterranean Sea)

Stable isotope ratios of six size fractions of zooplankton (80 to >2000 µm) were analyzed seasonally in 2009-2010 at the SOMLIT site in the Bay of Marseille. Isotopic ratios generally increased with zooplankton size. The highest δ15N values were observed in the 1000-2000 µm fraction. The largest size class (>2000 µm), dominated by gelatinous plankton, had lower δ15N values due to the low isotopic signatures of most of these organisms. In the larger size fractions (>1000 µm), isotopic ratios were measured at the taxon level. Brachyuran, stomatopod, teleost and cephalopod larvae showed the highest δ15N values, and salps and pteropods the lowest ones. Lower values of both δ13C and δ15N were recorded in winter and spring than in summer and autumn for all fractions. Seasonal variations were consistent with the fluctuations of environmental parameters (temperature, nutrients, Chl a concentration) and were related to phytoplankton and seawater particulate organic matter (POM) composition. Stable isotope and flow cytometry analysis of water POM indicated that sewage wastewater particles were mixed with marine phytoplankton at the SOMLIT site and transferred up into the zooplanktonic food web.

Simulation and preparation of surface EVA in reduced gravity at the Marseilles Bay subsea analogue sites

Extravehicular activity (EVA) of astronauts during space missions is simulated nowadays underwater in neutral buoyancy facilities. Certain aspects of weightlessness can be reproduced underwater by adding buoyancy to a diver-astronaut, therefore exposing the subject to the difficulties of working without gravity. Such tests were done at the COMEX’ test pool in Marseilles in the 1980s to train for a French–Russian mission to the MIR station, for the development of the European HERMES shuttle and the COLUMBUS laboratory. However, space agencies are currently studying missions to other destinations than the International Space Station in orbit, such as the return to the Moon, NEO (near-Earth objects) or Mars. All these objects expose different gravities: Moon has one sixth of Earth’s gravity, Mars has a third of Earth’s gravity and asteroids have virtually no surface gravity; the astronaut “floats” above the ground. The preparation of such missions calls for a new concept in neutral buoyancy training, not on man-made structures, but on natural terrain, underwater, to simulate EVA operations such as sampling, locomotion or even anchoring in low gravity. Underwater sites can be used not only to simulate the reduced gravity that astronauts will experience during their field trips, also human factors like stress are more realistically reproduced in such environment.The Bay of Marseille hosts several underwater sites that can be used to simulate various geologic morphologies, such as sink-holes which can be used to simulate astronaut descends into craters, caves where explorations of lava tubes can be trained or monolithic rock structures that can be used to test anchoring devices (e.g., near Earth objects). Marseilles with its aerospace and maritime/offshore heritage hosts the necessary logistics and expertise that is needed to perform such simulations underwater in a safe manner (training of astronaut-divers in local test pools, research vessels, subsea robots and submarines).COMEX is currently preparing a space mission simulation in the Marseilles Bay (foreseen in June 2012), and the paper will give an overview of the different underwater analogue sites that are available to the scientific community for the simulation of surface EVA or the test of scientific instruments and devices.

Possible bloom of free trichomes in the Bay of Marseille, NW Mediterranean Sea: an anomaly evidenced by flow cytometry

The composition of ultraphytoplankton ( 7 × 104 events mL−1), with both orange and red fluorescence intensities like Synechococcus, but with a size signal larger than that of 2 µm fluorospheres (beads). These unknown particles were sorted out by flow cytometry and then observed by epifluorescence microscopy: they appeared to be chain-forming microorganisms, just like trichomes of some diazotroph cyanobacteria with one heterocyst, but not unambiguously distal. The chains observed after cell sorting were not straight, but rather folded. To our knowledge, this is the first report of a possible bloom of such free trichomes. The small sample volume available for the delayed analysis and the limited resolution of our photomicrography did not allow for species identification. The brief occurrence of free trichomes in the Bay of Marseille with such a high abundance remains to be explained. High temperature in summer, induced stratification of the water column and nitrate depletion may be related to this event. High-frequency surveys of ultraphytoplankton assemblages at the single cell level appear to be necessary to observe such phenomenon more efficiently and document their dynamics.