Éditeur(s) : Université de Bretagne Occidentale
Résumé : This activity report entitled (“Chemical contamination of the marine environment: from measurement to risk assessment”) summarizes the main stages my career at Ifremer from November 1975 to june 2013. The first chapter deals with the seawater chlorination and chlorinated waters released into the sea, the identification and the conditions of the formation of various by-product of these processes. The second chapter concerns PCBs, their nature, their chemical analysis in environmental matrices. PCBs are considered as the best examples of persistant and bioaccumulable compounds and therefore, in all this report they are flagship contaminants to which other groups of studied substances are compared. The third chapter refers to studies performed within marine pollution monitoring programme RNO (Réseau National d’Observation de la qualité de l’environnement marin - National observation network on the quality of the marine environnment) and well as other more limited studies like a first assessement on the presence of dioxins and dioxin-like PCBs in the French coastal marine environment and last, on the use of zebra mussel (Dresseinia polymorpha) as sentinelle species of the chemical contamination in the Seine estuary. The next two chapters are about bioaccumulation and about the distribution of organic contaminants (PCBs, dioxins, PAHs, PBDEs) in marine organisms and in marine foodwebs. These studies aim at a better knowledge of the presence and fate of these compounds in fish and marine organisms eitheir in an environmental perspective (chapter IV) or in order to contribute to the assessment of their health impact, or more precisely to estimate therelative part of fish and seafood to the human exposure to chemical residues (chapter V). To conclude, the chapter VI concerns the PCB and dioxin fingerprints in the various studied marine matrices ; analytical and environmental interpretations of the observed differences are suggested as well as possible applications.
Ce bilan d’activité intitulé « Contamination chimique du milieu marin : de la mesure à l’évaluation des risques » retrace les étapes essentielles de mon parcours à Ifremer entre novembre 1975 et juin 2013. Le premier chapitre traite de la chloration dans l’eau de mer et les rejets chlorés en mer, l’identification des sous-produits formés lors de ces traitements, les conditions de leur formation. Le second chapitre concerne la nature des PCB et leur analyse dans les matrices environnementales. Les PCB considérés comme les meilleurs exemples de composés persistants bioaccumulables constituent les « contaminants phares » de l’ensemble de ce travail et c’est par rapport aux PCB que sont comparés et évalués les autres groupes de contaminants étudiés. Le troisième chapitre se rapporte aux travaux réalisés dans le cadre de la surveillance RNO (Réseau National d’Observation de la qualité de l’environnement marin) ainsi que dans des études ponctuelles comme un premier inventaire sur les niveaux de présence des dioxines (PCDD et PCDF) dans l’environnement marin littoral ou sur l’utilisation de la moule zébrée (Dresseinia polymorpha) comme espèce indicatrice de la contamination de l’estuaire de la Seine. Les deux chapitres suivants sont consacrés aux travaux sur la bioaccumulation et aux contaminants organiques (PCB, dioxines, HAP, PBDE) dans les organismes et les réseaux trophiques marins soit dans une perspective environnementale sur le devenir des contaminants dans le vivant (chapitre IV) soit dans le cadre de l’évaluation des risques sanitaires ou, plus précisément, de l’estimation de la contribution de la consommation des produits de la mer à l’exposition de l’homme aux résidus chimiques (chapitre V). Pour terminer, le chapitre VI concerne les empreintes de PCB et de dioxines dans les différentes matrices étudiées ; une interprétation analytique et environnementale des différences observées est proposée ainsi que de possibles applications.

Droits : 2013 UBO
http://archimer.ifremer.fr/doc/00168/27946/26237.pdf
http://archimer.ifremer.fr/doc/00168/27946/

Éditeur(s) : HAL CCSD Elsevier
Résumé : In this study, we assessed past and present influence of ancient mining activity on metal(loid) enrichment in sediments of a former mining watershed (Gardon River, SE France), that is now industrialized and urbanized. A sedimentary archive and current sediments were characterized combining geochemical analyses, zinc isotopic analyses and sequential extractions. The archive was used to establish local geochemical background and recorded (i) increasing enrichment factors (EFs) for Pb, Zn, Cd, Tl, Hg, As and Sb throughout the industrial era, (ii) a contamination peak in 1976 attributed to a tailings dam failure, and (iii) current levels in 2002 and 2011 similar to those of 1969, except for Sb and Hg, reflecting a persisting contamination pattern. Inter-element relationships and spatial distribution of EF values of current sediments throughout the watershed suggested that both ancient and current contamination had a common origin for Pb, Zn, Cd, Tl and As related to the exploitation of Pb/Zn mineralization while old Sb mines and coal extraction area were the main sources for Sb and Hg respectively. This prevailing mining origin was reflected for Zn by a relatively uniform isotopic composition at δ66Zn = 0.23 ± 0.03‰, although slight decrease from 0.23‰ to 0.18‰ was recorded from upstream to downstream sites along the river course in relation with the contribution of the lighter δ66Zn signature (~ 0.08‰) of acid mine drainage impacted tributaries. Results from sequential extractions revealed that the potential mobility of the studied metal(loid)s varied in the order Sb < Tl ≈ As < Zn < Pb < Cd, with an increase of the mobile pool for Cd, Pb, Zn and to a lesser extent for As and Tl associated to increased enrichment. Altogether, these results tend to demonstrate that ancient mining activity still contributes to metal enrichment in the sediments of the Gardon River and that some of these metals may be mobilized toward the water compartment.
ISSN: 0048-9697

hal-01054163
https://hal.archives-ouvertes.fr/hal-01054163
DOI : 10.1016/j.scitotenv.2014.02.078

Éditeur(s) : HAL CCSD
Résumé : International audience
The most active deep convection area in the western Mediterranean Sea is located in the Gulf of Lions. Recent studies in this area provides some insights on the complexity of the physical dynamics of convective regions, but very little is known about their impacts on the biogeochemical properties. The CASCADE (CAscading, Surge, Convection, Advection and Downwelling Events) cruise, planed in winter 2011, give us the opportunity to compare vertical profiles of properties sampled either during stratified conditions or after/during a convection event. In the present study, we focus on the distributions of the carbonate system properties (mainly total alkalinity, AT; and total dissolved inorganic carbon, CT) because, in the context of the climate change, deep convection areas are suspected to significantly increase the sequestration of anthropogenic CO2 (CANT). Given its limited size, the impact of the Mediterranean Sea on the global carbon budget is probably minor but this marginal sea can be used as a laboratory to better understand carbon sequestration and its transfer to the basin interior by deep convection processes. Distributions of AT and CT, both measured from bottle samples, and that of CANT (estimated with the TrOCA approach) are first analyzed in the light of other key properties (salinity, temperature, and dissolved oxygen). An objective interpolation procedure is then applied to estimate CT and AT from CTD measured properties. With this procedure, the vertical resolution goes from a maximum of 32 samples per station to one property estimate every meter (more detailed distributions are obtained). Results provide arguments to conclude that CANT is rapidly transferred to the deepest layer due to deep convection events. During deep convection events, the increase of CANT in the water column is positively correlated to that of potential density and oxygen content. The challenge of quantifying the amount of sequestered carbon is however not resolved due to the complexity and the highly dynamical nature of the convective regions. Deep convection in the Gulf of Lions, in parallel with cascading along the continental slope, could thus potentially explain the very high levels of both CANT and acidification estimated in the deep layers of the western Mediterranean Sea.
Deep Sea Research Part I: Oceanographic Research Papers

hal-01336725
https://hal-univ-perp.archives-ouvertes.fr/hal-01336725
DOI : 10.1016/j.dsr.2016.04.003

Éditeur(s) : Elsevier Science Inc
Résumé : Based on multi-sensor optical remote sensing techniques, more than 80 medium and high spatial resolution satellite images were used for studying the turbidity patterns of Danube Delta waters. During a selected 4-year temporal coverage (2006 to 2009), the turbidity gradients were simultaneously analyzed in the delta plain lakes and in the Black Sea western-northwestern coastal zone. Two distinct, but complementary, methodologies for retrieving turbidity were employed, one for the lakes and the other for the coastal zone. After comparing the turbidity satellite-derived turbidity products with in-situ measurements, the inter-comparability of the products was independently verified. Then, through an integrative analysis, the initial hypothesis of turbidity control by the Danube River inputs was tested in both areas (Delta plain and coastal zone). Seasonal turbidity patterns were identified together with the mechanisms responsible for its important temporal and spatial variability. Reciprocal contributions derived from the association of multi-scale satellite products were highlighted. (C) 2013 Elsevier Inc. All rights reserved.
Remote Sensing Of Environment (0034-4257) (Elsevier Science Inc), 2013-05 , Vol. 132 , P. 86-101

Droits : 2013 Elsevier Inc. All rights reserved.
http://archimer.ifremer.fr/doc/00135/24622/23607.pdf
DOI:10.1016/j.rse.2013.01.009
http://archimer.ifremer.fr/doc/00135/24622/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The contourite depositional system (CDS) along the southwestern Iberian Margin (SIM), within the Gulf of Cadiz and offshore areas of western Portugal bear the unmistakable signal of Mediterranean Outflow Water (MOW) exiting the Strait of Gibraltar. This locality records key information concerning the effects of tectonic activity on margin sedimentation, the effects of MOW dynamics on Atlantic circulation, and how these factors may have influenced global climate. Over the last four decades, numerous studies have been conducted on the late Miocene, Pliocene and Quaternary sedimentary stacking pattern of Neogene basins along the SIM for both academic and resources exploration purposes. However, understanding of the region rests primarily on basic seismic stratigraphy calibrated with limited data from only a few exploration wells. The Integrated Ocean Drilling Program (IODP) Expedition 339 recently drilled five sites in the Gulf of Cadiz and two sites on the western Iberian margin. The integration of core and borehole data with other geophysical databases leads us to propose a new stratigraphic framework. Interpretation of IODP Exp. 339 data along with that from industry sources and onshore outcrop analysis helps refine our understanding of the SIM's sedimentary evolution.We identify significant changes in sedimentation style and dominant sedimentary processes, coupled with widespread depositional hiatuses along the SIM within the Cadiz, Sanlucar, Doñana, Algarve and Alentejo basins. Following the 4.5 Ma cessation of a previous phase of tectonic activity related to the Miocene–Pliocene boundary, tectonics continued to influence margin development, downslope sediment transport and CDS evolution. Sedimentary features indicate tectonic pulses of about 0.8–0.9 Ma duration with a pronounced overprint of ~ 2–2.5 Ma cycles. These more protracted cycles relate to the westward rollback of subducted lithosphere at the convergent Africa-Eurasia plate boundary as its previous NW–SE compressional regime shifted to a WNW–ESE direction. Two major compressional events affecting to the Neogene basins at 3.2–3 Ma and 2–2.3 Ma help constrain the three main stages of CDS evolution. The stages include: 1) the initial-drift stage (5.33–3.2 Ma) with a weak MOW, 2) a transitional-drift stage (3.2–2 Ma) and 3) a growth-drift stage (2 Ma-present time) with enhanced MOW circulation into the Atlantic and associated contourite development due to greater bottom-current velocity. Two minor Pleistocene discontinuities at 0.7–0.9 Ma and 0.3–0.6 Ma record the effects of renewed tectonic activity on basin evolution, appearing most prominently in the Doñana basin. Several discontinuities bounding major and minor units appear on seismic profiles. Quaternary records offer the clearest example of this, with major units of about 0.8–0.9 Ma and sub-units of 0.4–0.5 Ma. Sedimentation is controlled by a combination of tectonics, sediment supply, sea-level and climate. This research identifies time scales of tectonic controls on deep-marine sedimentation, specifically over periods of 2.5–> 0.4 Ma. Shorter-term climatic (orbital) mechanisms control sedimentation at time scales of ≤ 0.4 Ma. The role of bottom water circulation and associated processes in shaping the seafloor and controlling the sedimentary stacking pattern on continental margins has to be seriously reconsidered in future multidisciplinary studies. This is not only because of the common occurrence of sandy contourite deposits in deep water setting and their economic interest for hydrocarbon exploration, but principally because they archive the heartbeat of the interior Earth and therefore have important sedimentary and paleoceanographic implications.
ISSN: 0025-3227

hal-01356166
https://hal.archives-ouvertes.fr/hal-01356166
DOI : 10.1016/j.margeo.2015.09.013

Éditeur(s) : Blackwell science
Résumé : The co-culture of juvenile sea cucumber Holothuria scabra (Jaeger), or 'sandfish', with juvenile blue shrimp Litopenaeus stylirostris (Stimpson) was tested by growing groups in co-culture and monoculture for 3 weeks in tanks with enriched sand substratum. Feed was supplied on trays, accessible only to shrimp. Survival of shrimp and sandfish was high in all treatments (73-100%). Growth of shrimp did not differ between monoculture and co-culture, but sandfish grew significantly slower in co-culture (P=0.03), although their sand burying and surface foraging were apparently unaffected by shrimp (P=0.76). However, shrimp increased the levels of total ammonia-N in tanks, which related inversely with sandfish growth (P=0.04). Conversely, sandfish did not appear to lower the water quality for shrimp culture. While sandfish bioturbate sediments and eat organic deposits, the juveniles did not significantly reduce the organic content of sand in tanks. Co-culturing juveniles of the two species in earthen ponds appears feasible, with no detriment to shrimp production, presenting a cost-effective method for growing sandfish to larger sizes for restocking. These findings underpin further studies to test the viability of commercial co-culture of sandfish with blue shrimp at later stages in the production cycle of shrimp.
Aquaculture Research (1355-557X) (Blackwell science), 2006-03 , Vol. 37 , N. 5 , P. 515-522

Droits : 2006 Blackwell Publishing, Inc.
http://archimer.ifremer.fr/doc/2006/publication-1356.pdf
DOI:10.1111/j.1365-2109.2006.01458.x
http://archimer.ifremer.fr/doc/00000/1356/

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
Marine ecosystems cover about 70% of the planet surface and are still an underexploited source of useful metabolites. Among microbes, filamentous fungi are captivating organisms used for the production of many chemical classes of secondary metabolites bound to be used in various fields of industrial application. The present study was focused on the collection, isolation, screening and genotyping of pigmented filamentous fungi isolated from tropical marine environments around La Réunion Island, Indian Ocean. About 150 micromycetes were revived and isolated from 14 marine samples (sediments, living corals, coral rubble, sea water and hard substrates) collected in four different locations. Forty-two colored fungal isolates belonging to 16 families, 25 genera and 31 species were further studied depending on their ability to produce pigments and thus subjected to molecular identification. From gene sequence analysis, the most frequently identified colored fungi belong to the widespread Penicillium, Talaromyces and Aspergillus genera in the family Trichocomaceae (11 species), then followed by the family Hypocreaceae (three species). This study demonstrates that marine biotopes in La Réunion Island, Indian Ocean, from coral reefs to underwater slopes of this volcanic island, shelter numerous species of micromycetes, from common or uncommon genera. This unstudied biodiversity comes along with the ability for some fungal marine inhabitants, to produce a range of pigments and hues.
ISSN: 2309-608X

hal-01657071
http://hal.univ-reunion.fr/hal-01657071
http://hal.univ-reunion.fr/hal-01657071/document
http://hal.univ-reunion.fr/hal-01657071/file/14-%20Fouillaud%20et%20al.%2C%20J.%20of%20Fungi%202017.pdf
DOI : 10.3390/jof3030036

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : La Martinique possède 55 km2 de récifs coralliens, 50 d’herbiers et 20 de mangroves. Ces trois écosystèmes produisent des biens et services dont la valeur est estimée à quelque 250 millions d’euros par an. Près de 60 % de cette valeur est issue des usages directs liés aux activités récréatives (plongée, excursion, récréation balnéaire) induites pour l’essentiel par le tourisme et celles liées à la pêche (professionnelle et de plaisancière). Les services écosystémiques (assimilés aux usages indirects) tels que la protection des côtes, l’absorption/séquestration de carbone, la production de biomasse de poissons et l’épuration de l’eau sont conséquents puisque leur valeur annuelle s’élève à 94 millions € soit 38 % de la valeur totale. La valeur de ce qui a trait au non-usage des récifs, herbiers et mangroves (lié à la volonté de transmettre un patrimoine écologique pour l’essentiel ou encore à la satisfaction de savoir que les récifs sont en bon état) se traduit par une création de valeur de l’ordre de 10 millions €/an. Les herbiers et les mangroves contribuent le plus (par km2) à la création de valeur (respectivement 2,16 millions €/km2, 1,87 million €/km2 contre 1,78 million €/km2 pour les récifs). Ils doivent donc bénéficier de mesures de protection et surtout de valorisation au même titre que les récifs coralliens qui font déjà l’objet d’une attention particulière.
Martinique possesses 55 km2 of coral reefs, 50 of sea grass and 20 of mangroves. These three ecosystems produce services for a value estimated at 250 millions € per year. About 60% of this value originates from directs uses such as recreational activities (diving, excursions, beach activities, etc.) induce by tourism and fishery. Ecosystem services (indirect uses) such as coastal protection, carbon sequestration, biomass production and water purification are significant since their sum value reaches annually 94 millions € (38% of the total economic value). Non-use value links to the improvement of the health of coastal ecosystem is estimated to 10 millions € per year. At the ecosystem level, sea grass and mangrove contribute the more (per km2) to the wealth creation (respectively 2,16 millions €/km2, 1,87 million €/km2 against 1,78 million €/km2 for the reefs). They need therefore to benefit from protection and management measures in the same magnitude than the reefs already received.
Martinique

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.4410
http://journals.openedition.org/etudescaribeennes/4410

Éditeur(s) : Elsevier
Résumé : Analysis of new high-resolution seismic-reflection profiles, chirp profiles and previously published sidescan data, together with piston cores on the Danube Fan provide new insight into the recent sedimentation processes in the deep northwestern Black Sea.The latest channel-levee system on the Danube Fan developed probably during the Neoeuxinian lowstand (oxygene isotope stage 2) in a semi-freshwater basin with a water level about 100 m lower than today. Sediment supplied by the Danube was transported to the deep basin through the Viteaz Canyon, which was directly connected to the leveed channel of this system on the middle slope. Channel avulsion was common in the middle fan, as indicated by four main phases of bifurcation. Each phase developed after the same pattern: breaching of the lower and narrower left levee by turbidity currents, building of a unit of High Amplitude Reflection Packets (HARP) by the unchannelized flow while the former channel was abandoned, followed by initiation of a new meandering leveed channel. The northward migration through successive bifurcations is influenced by the asymmetry between levees, hence by the Coriolis effect. In the lower fan where the levees became too low to maintain a stable pathway for the turbiditic flows, channel migration occurred. Locations of HARPs and channels after bifurcation are controlled by the pre-existing bathymetry. Sedimentary deposits are confined between the high levees of unit 0 (the initial phase of the youngest channel-levee system) to the south, and the steep relief of the Dniepr Fan to the north.The HARPs of the most recent phase of avulsion are the most severely constrained by local topography and form a very narrow elongate structure that is at most half as thick as the previous HARPs. Their distal part is not covered by channel-levee systems and is visible both on sidescan mosaics and on chirp profiles and was sampled in core BLKS 98-20.Sea level controlled fan activity but the evolution of the last channel-levee system with several bifurcations during a single sea level lowstand suggests that the primary control of channel avulsion and sand delivery is probably autocyclic.The presence of important HARP sand bodies in the mud-rich Danube Fan is presumed by analogy with a similar seismic facies on the Amazon Fan and indicated by the sands cored in BLKS98-20. However, only drilling of the HARP units could verify this interpretation.
Marine Geology (0025-3227) (Elsevier), 2001-09 , Vol. 179 , N. 1-2 , P. 25-37

Droits : 2001 Elsevier Science B.V. All rights reserved
http://archimer.ifremer.fr/doc/2001/publication-474.pdf
DOI:10.1016/S0025-3227(01)00197-9
http://archimer.ifremer.fr/doc/00000/474/

Éditeur(s) : HAL CCSD
Résumé : Time-series bathymetric data acquired between 1991 and 2011 have been used to evaluate the recent morphological evolution of the Nice upper continental slope (SE France, Ligurian Sea). Small-scale landslides lead to a retrogressive evolution of the continental shelf/upper slope transition but their frequency, size and impact are not well known. Mapping was undertaken to identify the morphology of landslide scarps and the location of the shelfbreak. Map comparisons were performed using ArcGIS “raster calculator”. Sediment remobilization on the upper slope (up to depths of 200 m) is fast and significant; landslide scars with volumes greater than 25,000 m3 can appear with a frequency less than 8 years. Shelfbreak migration toward the coastline can reach rates of 60 m over 7–8 years where the continental shelf is over 200 m wide. Furthermore, this quantitative analysis highlights alternations between periods of strongly erosive events and sedimentation periods. On the upper slope, eroded volumes can be multiplied by 10 during periods of enhanced landslide patterns (1999–2006). Such cycle-like landslide activity raises the issue of the triggering processes. On the Nice continental slope thick poorly consolidated beds rapidly deposited on a steep slope, earthquakes and rainfall leading to fresh water circulation below the shelf were identified as potential triggers. Our 4D bathymetric study suggests that over the last 20 years the greatest impacting factor may be freshwater outflows.
Engineering Geology for Society and Territory - Volume 4

hal-01218436
https://hal.archives-ouvertes.fr/hal-01218436
DOI : 10.1007/978-3-319-08660-6_42

Éditeur(s) : Amer Geophysical Union
Résumé : The freshest surface waters in the tropical Pacific are found at its eastern boundary. Using in situ observations, we depict the quasi-permanent presence of a far eastern Pacific fresh pool with Sea Surface Salinity (SSS) lower than 33, which is confined between Panama's west coast and 85W in December and extends westward to 95W in April. Strong SSS fronts are found at the outer edge of this fresh pool. We investigate the seasonal dynamics of the fresh pool using complementary satellite wind, rain, sea level and in situ oceanic current data at the surface, along with hydrographic profiles. The fresh pool appears off Panama due to the strong summer rains associated with the northward migration of the ITCZ over Central America in June. During the second half of the year, the eastward-flowing North Equatorial Counter Current keeps it trapped to the coast and strengthens the SSS front on its western edge. During winter, as the ITCZ moves southward, the north-easterly Panama gap wind creates a south-westward jet-like current in its path with a dipole of Ekman pumping/eddies on its flanks. As a result, upwelling in the Panama Bight brings to the surface cold and salty waters which erode the fresh pool on its eastern side while both the jet current and the enhanced South Equatorial Current stretch the fresh pool westward until it nearly disappears in May. New SMOS satellite SSS data proves able to capture the main seasonal features of the fresh pool and monitor its spatial extent.
Journal Of Geophysical Research-oceans (0148-0227) (Amer Geophysical Union), 2012-04 , Vol. 117 , P. -

Droits : 2012 AGU
http://archimer.ifremer.fr/doc/00072/18311/16581.pdf
DOI:10.1029/2011JC007802
http://archimer.ifremer.fr/doc/00072/18311/

Éditeur(s) : HAL CCSD Station Biologique
Résumé : International audience
This study deals with temporal variations in eel diet Anguilla anguilla sampled at each of the four seasons in the Languedocian Prévost lagoon (Gulf of Lion) from Autumn 1998 to Summer 1999. The following feeding indices were calculated based on observations of 12 categories of prey found in the contents of full stomachs: coefficient of vacuity CV, degree of fullness DR, occurrence frequency PP, relative abundance N (in %) and relative weight P (in %). The interpretation of results is also based on the Costello's method (1990) which combines PP and N. Anguilla anguilla mainly feeds on benthic organisms, primarily Gammarus gr. locusta, Polychaeta, insect larvae, small fish. Based on variations in eel diet, seasonal influence is illustrated by a decrease in feeding activity in summer which gradually increases during the following seasons. The good trophic quality available to eels in the Prévost lagoon depends on its hydrodynamics which is directly related to the movement of water entering and leaving lagoon by a short communication with the sea. This water movement accelerates the enrichment and production processes of this ecosystem. Changes observed during the four seasons illustrate an opportunistic type of feeding behaviour. Eels consume the most available benthic prey. They favour the importance of the prey at a given moment without using a particular feeding strategy like specialisation or generalisation. Thus, eel adapts its diet in adjusting available energy resources in the ecosystem. Because of this, the lagoon-resident species Anguilla anguilla is an obvious indirect bioindicator of the trophic capacity and present level of confinement in the brackish water lagoon ecosystem of Prévost.
ISSN: 0007-9723

hal-00753021
https://hal.univ-antilles.fr/hal-00753021

Éditeur(s) : Elsevier
Résumé : During the Fanindien 2006 cruise of R/V 'Beautemps-Beaupre', high resolution multibeam bathymetry, sub-bottom profiling and sediment coring was carried out along the East African margin, offshore Tanzania and Mozambique (Indian Ocean). The newly acquired data reveal the presence of a giant deep-sea valley (the Tanzania channel) that is more than 10 km wide at 4000 m water depth, along the continental rise. The valley remains similar to 70 m deep and 7 km wide at 800 km from the Tanzania coast. Morphological comparison with worldwide submarine channels show that the Tanzania channel is one of the largest known submarine valleys. This discovery brings new light on development of submarine valleys that drain sediments originated from the East African Rift System (EARS) highlands (i.e. the Tanzania channel and its neighbor Zambezi channel located similar to 1000 km southward). Both of the systems have a morphology markedly different to the classical sinuous, V-shaped channels located at similar latitudes (e.g. the Zaire or Amazon channels). Their submarine drainage system consists of a downslope converging tributary canyons joining a central trunk channel in the continental rise. The presence of such giant deep-sea drainage systems is probably linked to a strong structural control on the sediment pathway, associated to a massive sediment transfer towards the Indian Ocean in relation with the tectonic activity of the East African Rift System (i.e. the uplift periods trough mid-Miocene and Plio-Pleistocene times) and its interplay with the East African equatorial climate changes. (C) 2008 Elsevier B.V. All rights reserved.
Marine Geology (0025-3227) (Elsevier), 2008-12 , Vol. 255 , N. 3-4 , P. 179-185

Droits : 2008 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2008/publication-6855.pdf
DOI:10.1016/j.margeo.2008.09.002

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Cet article présente une évaluation des bénéfices de la protection par le Conservatoire du littoral et ses partenaires des mangroves de Guyane, Guadeloupe, Martinique, Mayotte et Saint-Martin. Il détaille l’évaluation des services écosystémiques des mangroves sur ces territoires, puis développe des projections pour l’évolution de leurs surfaces en présence ou en absence de protection par le Conservatoire du littoral et ses partenaires. Évaluation et projections ont permis d’estimer les conséquences économiques de cette protection sur 25 ans. Les bénéfices calculés de cette protection sont compris entre 33 000 €/ha et 51 000 €/ha pour les mangroves soumises à des pressions anthropiques importantes. Le maintien des services de régulation correspond à 90 % de cette valeur, surtout pour la capacité des mangroves à épurer les eaux continentales, à protéger et stabiliser la côte et à participer à la régulation du climat global en séquestrant du carbone. Ces résultats objectivent la place des mangroves dans l’économie locale du littoral outre-mer et offrent un plaidoyer pour l’acquisition et la protection des espaces les plus vulnérables par le Conservatoire du littoral et ses partenaires. Les limites inhérentes aux méthodologies utilisées s’appliquent ici : ces évaluations permettent de capter les valeurs d’usage des écosystèmes, mais ne prennent pas en compte la totalité des valeurs de biodiversité, telles que les valeurs de non-usage ou les aspects liés aux espèces remarquables des mangroves. Toutefois, les résultats de ce travail permettent de donner des estimations réalistes à considérer comme des bornes inférieures de la valeur totale des écosystèmes et de leur protection.
This article presents a valuation of the benefits brought by the protection of mangroves from the Conservatoire du littoral and its partners in French Guiana, Guadeloupe, Martinique, Mayotte and Saint Martin. We detail a contextualized mangroves’ ecosystem services valuation, then develop projections regarding the evolution of their surfaces whether they are protected or not. It was then possible to estimate the economic impacts of 25 years of mangroves protection. When human pressure is high, those benefits range from 33 000 €/ha to 51 000 €/ha. About 90% of this value is due to the conservation of regulating services, such as water treatment capacity, coastal protection and global climate mitigation through carbon sequestration. Our results objectify the importance of mangrove ecosystems in oversea coastal territories’ local economy, and provide advocacy and guidance for the protection strategy of the Conservatoire du littoral and its partners. The methodology we used has inherent limitations one should consider: the ecosystem services valuation focuses on use values and excludes most non-use or intrinsic values, which could also be important for mangroves regarding their remarkable biodiversity. However, our results supply a realistic valuation to be understood as a lower boundary for the total value of oversea mangroves and for the benefits of their protection.
Guadeloupe
Guyane française
Martinique
Mayotte
Saint-Martin

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.10485
http://journals.openedition.org/etudescaribeennes/10485

Éditeur(s) : HAL CCSD
Résumé : Manque : organisateur de la manifestation - éléments/proceedings
With the new data on bathymetry, currentology, in this ecosystem and the abiotic variables studied from February to May 2007, a review of the Manche-à-Eau’s biological zonation recently stated from the fishassemblage is proposed. The water volume turnover at each tide (14,8%) twice a day combined with an active and various hydrodynamism contribute to vivify the lagoon andprovide information for a better interpretation of the Well-Being Index values and the populational parameters gradients of the fish assemblage. During the studied period, no gradient is observed with the abiotic variables. The water characteristics are homogene-ous verywhere in the lagoon, in the water column and whatever the period studied (temperature: 30,02°C; salinity: 36,16 ‰; pH:8,29; turbidity: 6,10 mg/L; conductivity: 5,51S/m; dissolved oxygen: 7,18mg/L; dissolved solids: 32,78g/Ll; osmolarity:1021,7milliosmoles). A revised biological zonation of the Manche-à-Eau lagoon is pro-posed. According to the quality observed, it is made of three zones, instead four, from II to IV: the zone II is more spread at South and narrow along the island, the zone III occupies the geater part of the ecosystem and the zone IV centered on the two main depressions at South and West, on the shallows and its North-West border and the end of the sector enclaved at South-West.
Con los nuevos datos sobre batimetría y la corrientología en este ecosistema y las variables abióticas estudiadas de febrero a mayo del 2007, se propone una revisión de la zonación biológica recientemente establecida en cuanto a la agrupación de peces del Manche-à-Eau. El volumen de agua renovada dos veces al día en cada marea (14.8%) combinado a un hidrodinamismo activo y variado contribuyen a verificar la laguna, y aportan elementos para una mejor interpretación de los valores de los índices de buen estado y de los diferentes parámetros poblacionales de la ictiofáuna presente. Durante el período estudiado no se observó ningúngradiente con los parámetros abióticos. Las características del agua son homogéneas a lo largo de toda la laguna. En la columna de agua en cualquiera de los períodos considerados (temperatura: 30,02°C; salinidad: 36,16 ‰; pH: 8,29; turbidez: 6,10 mg/L;conductividad: 5,51 S/m; oxígeno disuelto: 7,18 mg/L; sólidos disueltos: 32,78g/L; osmolaridad: 1021,7miliosmoles). Se propone una zonación biológica rectificada. De acuerdo a la calidad observada, esta, está compuesta por tres zonas en lugar de cuatro: de II a IV, la zona II está mas dispersa al sur y es mas estrecha a lo largo de la isla, la zona III domina la mayor parte del ecosistema y lazona IV está centrada en las dos principales depresiones al sur y al oeste, las zonas someras y en su borde al noroeste al igual que del sector enclavado al suroeste.
Avec les nouvelles données sur la bathymétrie et la courantologie de cet écosystème et les paramètres physicochimiques étudiés entre février et mai 2007, c’est une actualisation de la zonation biologique établie récemment à partir de l’assemblage de poissons y séjournant qui est proposée dans cette étude. En effet, le volume d’eau renouvelé deux fois par jour à chaque marée (14,8%) combiné à un hydrodynamisme actif et varié contribuent à vivifier la lagune, et apportent des éléments pour une meilleure interprétation des valeurs des indices de bien-être et des gradients des paramètres populationnels de l’ichtyofaune présente. Durant la période étudiée, aucun gradient n’est observé avec les paramètres abiotiques. La caractéristique des eaux est homogène partout dans la lagune, sa colonne d’eau et aux différentes périodes considérées (température : 30,02°C ; salinité : 36,16 ‰ ; pH : 8,29 ; turbidité : 6,10 mg/L ; conductivité : 5,51 S/m ; oxygène dissous : 7,18 mg/L ; solides dissous : 32,78g/L ; osmolarité : 1021,7milliosmoles). Une zonation biologique rectifiée est proposée. Plus conforme à la qualité observée, elle est composée de trois zones, au lieu de quatre, allant de II à IV: la zone II un peu plus étendue au Sud et plus étroite le long de l’île, une zone III dominante sur l’ensemble de la lagune, et une zone IV centrée sur les deux principales dépressions au Sud et à l’Ouest, le haut-fond et sa bordure au Nord-Ouest ainsi que le fond du secteur enclavé au Sud-Ouest.
Proceedings of the 61st Gulf and Caribbean Fisheries Institute
Le Gosier, Guadeloupe, France

hal-01600920
https://hal.archives-ouvertes.fr/hal-01600920
PRODINRA : 384820

Éditeur(s) : Elsevier France-editions Scientifiques Medicales Elsevier
Résumé : The essential characteristics of the vegetation dynamics of tropical Africa remain only partially known. This study assesses the succession of vegetation-types over Central Africa during the last two glacial/interglacial cycles. Analysis of core KZai 02, which contains pollen from the Zaire River watershed (latitudes 9°N-13°S), allows the investigation of long-term patterns of plant ecosystem development and their climatic causes. Core KZai 02 (18.20 m long) was recovered from 6°24.20′S/9°54.10′E in the uppermost axial edifice of the Zaire deep sea fan. The chronology of this sedimentary archive was established using nannofossils and correlations of pollen and total organic carbon signals with the nearby core GeoB1008. The pollen record indicates that: (i) glacials (MIS 6, 4, 2) are marked by the development of afromontane (Podocarpus) forest at high altitudes when central basin lowlands were occupied by Cyperaceae marshes and savannah; (ii) during interglacials (MIS 1, 5) lowland forests were developed, marked by the successive expansion of pioneer, warm-temperate, rain forests, and mangrove indicating sea-level rise; (iii) glacial-interglacial transitions (MIS 6/5, 2/1) display similar vegetation dynamics. The strong evidence of afromontane forest and the opening of the vegetation during glacials suggest a reduced latitudinal distribution of rainfall by the strengthening of the trade wind system. West African monsoon systems were enhanced during interglacials, allowing the progressive development of lowland forests. The development of rain and pioneer forests during glacial Heinrich stadials suggests an enhancement of water availability in tropical Africa associated with these high latitude events. However, no augmentation of wind activity, described by previous studies, is evidenced by our pollen record. Similar vegetation successions during glacial/interglacial transitions suggest the diachronous and stepped intervention of CO2 (emphasizing the influence of temperature on plant ecosystems) and water availability.
Geobios (0016-6995) (Elsevier France-editions Scientifiques Medicales Elsevier), 2014-07 , Vol. 47 , N. 4 , P. 183-198

Droits : 2014 Elsevier Masson SAS. All rights reserved.
http://archimer.ifremer.fr/doc/00199/31031/29436.pdf
DOI:10.1016/j.geobios.2014.06.002
http://archimer.ifremer.fr/doc/00199/31031/

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : We report the northernmost and deepest known occurrence of deep-water pycnodontine oysters based on two surveys along the French Atlantic continental margin to the La Chapelle continental slope (2006) and the Guilvinec Canyon (2008) The combined use of multibeam bathymetry seismic profiling CTD casts and a remotely operated vehicle (ROV) made it possible to describe the physical habitat and to assess the oceanographic control for the recently described species Neopycnodonte zibrowii These oysters have been observed in vivo in depths from 540 to 846 m colonizing overhanging banks or escarpments protruding from steep canyon flanks Especially in the Bay of Biscay such physical habitats may only be observed within canyons where they are created by both long-term turbiditic and contouritic processes Frequent observations of sand ripples on the seabed indicate the presence of a steady but enhanced bottom current of about 40 cm/s The occurrence of oysters also coincides with the Interface between the Eastern North Atlantic Water and the Mediterranean Outflow Water A combination of this water mass mixing internal tide generation and a strong primary surface productivity may generate an enhanced nutrient flux which is funnelled through the canyon When the ideal environmental conditions are met up to 100 individuals per m(2) may be observed These deep-water oysters require a vertical habitat which is often incompatible with the requirements of other sessile organisms and are only sparsely distributed along the continental margins The discovery of these giant oyster banks illustrates the rich biodiversity of deep-sea canyons and their underestimation as true ecosystem hotspots (C) 2010 Elsevier Ltd All rights reserved
Deep-sea Research Part I-oceanographic Research Papers (0967-0637) (Pergamon-elsevier Science Ltd), 2010-12 , Vol. 57 , N. 12 , P. 1561-1572

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00023/13419/14034.pdf
DOI:10.1016/j.dsr.2010.09.002
http://archimer.ifremer.fr/doc/00023/13419/

Éditeur(s) : HAL CCSD
Résumé : International audience
The challenge is to implement research that can estimate the consequences ofclimate changes in terms of impact on terrestrial environments and resources.Emphasis should be placed on regions dependent on natural resources and forwhich demographic pressure is strong. Simulations obtained from climate modelprojections (using different Representative Concentration Pathways (RCPs))predict that the Mediterranean basin and its southern periphery are particularlyvulnerable to water resources and environmental impact (IPCC, AR5, 2013).An annual rainfall decrease by 30% is found for the projection period 2070-2099(IPCC, AR5, 2013) associated with a decrease in water resources by 30 to 50%(Milano, 2012). In addition, several studies using regional atmospheric modelsindicate an increase in the precipitation inter-annual variability with extremeevents and a spatial heterogeneous signature, superimposed on a decrease in thetotal precipitation amount (Giorgi and Lionello, 2008; Raible et al. 2010).Currently, regional climate projections are highly sensitive to the climate modelused. In particular, spatial resolution as well as local climate conditions seemto impact significantly on the simulations (Jacob et al. 2014).The Mediterranean region, at the interface between arid and temperate climateswith several mountainous areas, is a complex climate system affected by theinteractions between mid-latitude and sub-tropical processes. In this context,Morocco, located at the transition between a temperate climate to the North anda tropical climate to the south constitutes a key area for an impact and sensitivitystudy to global climate changes. The climate is influenced by the Atlantic Ocean,the Mediterranean Sea and the Sahara, together with a very steep orography inthe Atlas region. The precipitation distribution is therefore characterised by greatspatial variability, and exhibits a marked seasonality, a strong inter-annualvariability (Ouda et al. 2005) and in general a pronounced gradient from northto south and west to east. At a broader scale, Morocco is located on the subtropicalsubsidence path and between the Acores High and the Saharan Low (Agoussine,2003). Several studies have also identified strong links with inter-annualprecipitation variability and NAO index (Knippertz, 2003) as well as remoteclimate modes (Esper et al. 2007).Continental climate variability at a local/regional scale, if it is to be integratedin climate predictions, needs to be supported by long-term observation.Meteorological stations in Morocco provide climatic data mainly for the last40 years with only a few stations located in the mountainous region (Tramblayet al. 2012; 2013; Driouech et al. 2010). This climate database is also supportedby the IAEA network providing stations for which isotope tracers have beenapplied to daily/monthly rain and water vapour samples over 2 to 3 years between2000 and 2004. Besides the poor coverage of instrumented areas, lacustrinesystems can provide a climatic data set that offers access to short and long-termtime series of climate parameters when knowledge of modern lake water balanceis combined with lacustrine sedimentary-climate records. Lake sediment recordsideally provide high resolution climate/environmental information of the last10,000 years (Magny et al. 2013). This time interval (corresponding to theHolocene) is a key period to investigate short and long-term climate variabilityand to improve prediction in a warming climate.In this study we present an integrated approach focusing on a mountainous lake(Aguelmam Azigza). The modern lake system study is based on site monitoring(2012-2016) and available regional hydro-climatic data. These data show thatlake level changes during the instrumented period were mainly driven byprecipitation following the high inter-annual variability. These data are thencompared with accurately dated short sediment cores retrieved in the same lake.Micro-scale geochemical and sedimentological analyses of these sequencesenable us to identify various sedimentary facies that can be linked with periodsof high (low) lake levels over the past decades.
The Mediterranean Region under Climate ChangeLa méditerranée face au changement climatique

insu-01394690
https://hal-insu.archives-ouvertes.fr/insu-01394690
https://hal-insu.archives-ouvertes.fr/insu-01394690/document
https://hal-insu.archives-ouvertes.fr/insu-01394690/file/Vidaletal.2016-COP22-Chap1.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
Cytogenetics provides a unique platform to study in situ structural, functional, and evolutionary aspects of the genome. As such it holds powerful promise in decoding mechanisms and processes of genome architectural changes and their role in organism's diversification and evolution. Since the early 80s, such an approach has been applied to the study of the Antarctic notothenioid fishes. In almost three decades, the cytogenetic information has expanded to cover half of the known species inhabiting the high Antarctic waters. Although started 10 years later, cytogenetic studies of species from the Ross sea region have provided valuable contributions to this bulk of knowledge. Here, we synthesize the currently available cytogenetic information on Antarctic notothenioid fishes from the Ross Sea Region, inclusive of both conventional karyotyping and gene mapping. In addition, new karyotypic data on four species (Lepidonotothen squamifrons, Trematomus scotti, T. loennbergii, and T. lepidorhinus) are provided. In discussing these data, specific focus is made on the patterns and subtleties of cytogenetic diversity at inter- and intra-specific levels aiming at contributing to the refinement of the knowledge of fish diversity in a region, the Ross Sea area, whose primary ecological value is widely recognized.
Hydrobiologia

hal-01544905
https://hal.archives-ouvertes.fr/hal-01544905
DOI : 10.1007/s10750-015-2355-5

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Almost all Red Sea deeps contain metal-rich sediments covered by brine pools. It is generally agreed that these metal-rich deposits precipitated from overlying metal-rich brines that originated from migrating hydrothermal fluids. No brine pool has ever been reported in Thetis Deep, inciting us to evaluate if such a brine layer ever occurred in the deep during the past. In order to address that questioning, a study combining mineralogical, geochemical (major-, minor-, rare-earth elements) and isotopic (Sr. Nd. Pb) approaches was completed on cored sediments and extracted interstitial waters from inside and outside the deep.;The sediments have an overall hydrothermal origin, as shown by the REE concentrations and patterns, metal contents, and Pb-Nd isotopic data, all pointing to a mantle signature. The intensity of the hydrothermal activity varied with time in the deep; the most intense episode resulting in an almost pure Fe-oxi-hydroxide layer. Varied chemical arguments, especially the Zr and REE data of the sediments, favor the fact that the whole sedimentation in Thetis Deep occurred in the absence of a stable, salt-rich and mineralized brine pool, and that no brine layer ever existed. This conclusion is supported by the constant Sr isotope composition of the sediment and its interstitial waters that are almost identical to that of the Red Sea seawater. The study also suggests that hydrothermal activity monitored fluid supplies that interacted differently with seawater in the different Red Sea deeps, resulting in an overall formation of metal-rich sediments, but along varied local conditions. (C) 2009 Elsevier B.V. All rights reserved.
ISSN: 0375-6742

hal-00475646
https://hal.archives-ouvertes.fr/hal-00475646
DOI : 10.1016/j.gexplo.2009.10.001