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12 pages, 5 figures, 1 table, supplementary material in https://doi.org/10.3354/meps09333, The Mediterranean deep sea, being isothermal and longitudinally trophic-graded, is an optimal natural benchmark to test for macro-ecological patterns of species distribution. The relevance of environment-biota interactions on deep-sea megafauna in the Mediterranean Sea, a matter still neglected, is addressed here along longitudinal and bathymetric axes. Benthic and nektobenthic megafauna were collected in the 3 basins of the Mediterranean: the western (Catalan Sea and southern Balearic), central (western Ionian) and eastern (south of Crete) basins, with an otter-trawl Maireta system and an Agassiz dredge between 1200 and 4000 m depth. Simultaneously, environmental data were collected on surface production, near-bottom physical parameters, sediment grain size and carbon content. Megafaunal biomass was higher in the Catalan Sea, decreasing eastward and with depth. Species diversity and evenness were relatively constant in the western and central Mediterranean at all depths, whereas these indices decreased with depth in the eastern Mediterranean. β-diversity analyses indicated a high species turnover between areas. The 3 basins presented significantly different environmental conditions. Sediment particulate organic carbon, surface fluorescence and sediment grain size were the 3 environmental variables that best explained the distribution of megabenthos along the longitudinal Mediterranean axis. These results show that the food supply, from either the surface or from the adjacent deepsea floor, is critical in regulating the biodiversity of deep-sea Mediterranean megafauna and that this diversity is pooled region-wide. The heterogeneity of resources may be essential in maintaining these high levels of local and regional diversity, This work was funded through the BIOFUN project (CTM2007-28739-E) by the European Science Foundation, the PROMETEO Spanish national project (CTM2007-66316- C02/MAR) by the CICYT and the European Community’s Seventh Framework Programme under the HERMIONE project (Grant Agreement 226354). Geological analyses were supported by projects GRACCIE-CONSOLIDER (CSD2007-00067), REDECO (CTM2008-04973-E/MAR) and a Generalitat de Catalunya ‘Grups de Recerca Consolidats’ grant (2009 SGR 1305). S.T. was funded by a JAE-PRE-2008 grant, and E.R.L. was funded by a JAE-DOC-2008 grant, both from the Spanish Research Council (CSIC), Spain

The present work analyses the seasonal evolution of planktonic assemblages and particle fluxes through the water column in the Eastern Alboran Sea (Western Mediterranean) at 35o55.47'N/01o30.77'W. A Sediment trap was deployed below the influence of the Almeria-Oran Front (AOF), a semi-permanent geostrophic front, during July 1997 to June 1998. Overall, the temporal variability of coccolithophore, planktonic foraminifer, diatom, benthic and wind-carried biogenic particle fluxes is linked to the seasonal evolution of sea surface hydrological structures. Maximum planktonic fluxes were found during high-productivity periods and wind-induced upwelling, following a trimodal pattern, with maximum fluxes in July 1997, November–December 1997, and April–May 1998. These periods were characterized by vertical mixing and the full development of anticyclonic gyres in the Alboran Sea. The annual flux of coccolithophores was dominated by the “small Gephyrocapsa Group” and Emiliania huxleyi, whereas Turborotalita quinqueloba and Globigerina bulloides dominated the foraminiferal fluxes, and Chaetoceros Resting Spores (RS) were predominant in the diatom assemblage. Benthic specimens were also collected with the sediment trap, suggesting a variable influence of bottom water activity. Wind-driven particles (phytoliths and fresh-water diatoms) were collected along the year, but their fluxes followed the local wind regime. The high Sea Surface Temperature (SST) during fall due to weaker than usual westerly winds, and the pressure anomaly prevailing in the Alboran Sea during early winter, were reflected in the planktonic assemblages by the proliferation of warm, lower photic layer inhabitants and/or oligotrophic taxa of coccolithophores (Florisphaera profunda), planktonic foraminifers (Globigerinoides ruber and Globorotalia inflata) and diatoms (Leptocylindrus danicus). These unusual climatic conditions in the eastern Alboran Sea must have been caused by the 1997–1998 ENSO event.

With the aim of improving the knowledge of the open ocean carbon cycle, we present a budget of particulate organic carbon (POC) fluxes carried out in the deep central part of the Algero-Balearic Basin (ABB) at 2850 m water depth based on a single mooring equipped with five automated sediment traps deployed from April 2001 to May 2002 at depths of 250, 845, 1440, 2145 and 2820 m. Suspended particulate matter (SPM) and superficial sediments were also used as indicators of hydrodynamics and carbon burial, respectively. The data reveal that the fraction of primary production buried in the sediment, which finally leads to the sequestration of carbon dioxide from the atmosphere, is 0.16%, lower than the values found in the nearby continental margin regions such as the Alboran Sea (0.48–0.89%) but of the same order as recorded at other Mediterranean sites at similar depths, such as the Ionian Sea (0.11%). As they sink through the water column, the particles exhibit decreases in flux that are similar to those observed elsewhere, but also show variations that appear to correlate with hydrological features of the water masses present in the basin, as revealed by SPM concentrations and compositions. The input of the tyrrhenian deep water (TDW) into the ABB at 800–1500 m of water depth exhibits low suspended POC concentrations and low sinking POC fluxes were also observed in this depth range. Gulf of Lions water mass formation appears to also contribute to elevated suspended POC concentrations and perhaps POC accumulation in the traps and sediments by spreading of dense cold water along the whole ABB that supplied POC at depths higher than 2000 m.

The carbon cycle of the Arctic Ocean is tightly regulated by land-atmosphere-cryosphere-ocean interactions. Characterizing these environmental exchanges and feedbacks is critical to facilitate projections of the carbon cycle under changing climate conditions. The environmental drivers of sinking particles including organic carbon (OC) to the deep-sea floor are investigated with four moorings including sediment traps and currentmeters at the Arctic gateway in the eastern Fram Strait, which is the area where warm anomalies are transported northwards to the Arctic. Particles fluxes were collected over one year (July 2010-July 2011) and have been analysed to obtain the content of the lithogenic fraction, calcium carbonate, OC and its stable isotopes, opal, and the grain size. Records of near bottom current speed and temperature along with satellite observations of sea ice extent and chlorophyll-a concentration have been used for evaluation of the environmental conditions.We found increased lithogenic fluxes (up to 9872mgm-2d-1) and coarsening grain size of settling particles in late winter-early spring. At the same time, intensifications of the northward flowing west Spitsbergen current (WSC) were recorded. The WSC was able to resuspend and transport northwards sediments that were deposited at the outlet of Storfjordrenna and on the upper slope west of Spitsbergen. The signal of recurrent winnowing of fine particles was also detected in the top layer of surface sediments. In addition, an increased arrival of sea ice transported ice rafted detritus (>414 detrital carbonate mineral grains larger than 1mm per m2) from the southern Spitsbergen coast along with terrestrial organic matter was observed beyond 1000m of water depth during winter months. Finally, the downward particle fluxes showed typical temporal variability of high latitudes, with high percentages of the biogenic compounds (opal, organic carbon and calcium carbonate) linked to the phytoplankton bloom in spring-summer. However, on an annual basis local planktonic production was a secondary source for the downward OC, since most of the OC was advected laterally by the WSC. Overall, these observations demonstrated the sensitivity of the downward flux of particles to environmental conditions such as hydrodynamics, sea ice rafting, and pelagic primary production. Future alteration of the patterns of natural drivers due to climate change is thus expected to cause major shifts in the downward flux of particles, including carbon, to the deep sea ecosystems. © 2015 Elsevier Ltd., This research has been supported by the projects HERMIONE (FP7-ENV-2008-1-226354) and GRACCIE-CONSOLIDER (CSD2007-00067), and a Catalan Government Grups de Recerca Consolidats grant (2009 SGR 1305). LL was partly supported by the CNR-DTA project SNOW (Sensor Network for Oceanography in shallow Water - Kongsfjord experiment), and AS by a “Ramon y Cajal” contract from MICINN. BF is affiliated with the Centre of Excellence: Arctic Gas hydrate, Environment and Climate (CAGE) funded by the Norwegian Research Council (grant no. 223259). We are grateful to S. Buenz and the crew of RV Helmer Hansen (University of Tromsø) for their valuable support during the cruises, and R. Duran, S. Kunesch, J. Carbonne, A. Rumin, S. Aliani, and X. Rayo who assisted with the field and laboratory work. This is contribution N. XXXX of the CNR-ISMAR of Bologna.

Surface sediments collected from deep slopes and basins (1018–4087 m depth) of the oligotrophic eastern Mediterranean Sea have been analysed for bulk elemental and isotopic composition of organic carbon, total nitrogen and selected lipid biomarkers, jointly with grain size distribution and other geochemical proxies. The distribution and sources of sedimentary organic matter (OM) have been subsequently assessed and general environmental variables, such as water column depth and physical circulation patterns, have been examined as causative factors of deep-sea sediment characteristics. Lithogenic and biogenic carbonates are the dominant sedimentary fractions, accounting for up to 85.4 and 66.5 % of the total weight respectively. The low OC and TN contents in the surface sediments of the study area, which ranged from 0.15 to 1.15 % and 0.06 to 0.11 % respectively, reflect the oligotrophic character of the eastern Mediterranean Sea. Both bulk and molecular organic tracers reflect a mixed contribution from autochthonous and allochthonous sources for the sedimentary OM, as indicated by relatively degraded marine OM, terrestrial plant waxes and anthropogenic OM (e.g. degraded petroleum by-products) respectively. Wide regional variations have been observed amongst the studied proxies, which reflect the multiple factors controlling sedimentation in the deep eastern Mediterranean Sea. Our findings highlight the role of deep eastern Mediterranean basins as depocentres of organic-rich fine-grained sediments (mean 5.4 ± 2.4 μm), with OM accumulation and burial being attributed to aggregation mechanisms and hydrodynamic sorting. A multi-proxy approach is applied aiming to investigate the biogeochemical composition of sediment samples, which sheds new light on the sources and transport mechanisms along with the impact of preservation vs. diagenetic processes on the composition of sedimentary OM in the deep basins of the oligotrophic eastern Mediterranean Sea.

8 pages, 3 figures, 2 tables, The finding of perfluoroalkyl substances (PFASs) in particles sinking to the deep northwestern Mediterranean Sea confirms the role of the latter as ballast for the transfer of pollutants to the deep sea. The transfer of particulate matter down to the deep is enhanced during atmosphere-driven, high-energy physical oceanographic processes like dense shelf water cascading (DSWC), which is caused by winter surface heat losses and evaporation. Here we present data from samples collected during winter 2012, when dense shelf water formation and subsequent cascading triggered the flushing of large amounts of PFASs through a submarine canyon to depths in excess of 1000. m. The finding of quantifiable concentrations of long-chain PFOA, PFOS and PFNA substances and significantly high concentrations of the short-chain substances PFHxA and PFBA indicates that these compounds, sorbed onto particulate matter, are quickly and directly transferred to the ocean's interior, thus highlighting the role of DSWC in removing those pollutants from the coastal ocean. Eventually, uncertainties about our results arising from the limited number of samples available are counterbalanced by their intrinsic value as intense DSWC events, like the one in 2012, occur only every 5-7. years in the study area, which seriously restricts sampling opportunities. Our results add PFASs to the list of persistent organic pollutants like polychlorinated biphenyls, chlorobenzenes or polycyclic aromatic hydrocarbons known to be conveyed to the deep marine environment. © 2015 Elsevier B.V., This research has been supported by PERSEUS (FP7-OCEAN-2011-3-287600), DOSMARES (CTM2010-21810-C03), and NUREIEV (CTM2013-44598-R) research projects, and the Generalitat de Catalunya (Consolidated Research Groups grants 2014 SGR 291, 2014 SGR 418 and 2014 SGR 1068). [...] AS is supported by a “Ramon y Cajal” contract from MICINN

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license., peer-reviewed

As part of the “Mediterranean Targeted Project II—MAss Transfer and Ecosystem Response” (MTPII-MATER) EU-funded research project, particle flux data was obtained from three instrumented arrays moored along the 1°30′ W meridian in the Eastern Alboran Sea. The mooring lines were deployed over 11 months, from July 1997 to May 1998, and were equipped with sediment trap-current metre pairs at 500–700, 1000–1200 and 2000–2200 m of water depth. The settling material was analysed to obtain total mass, lithogenic, calcium carbonate, organic carbon and opal fluxes. Integrated analysis of sediment trap and current meter data with sea-surface satellite images reveals that particle flux distribution is a function of primary production, mid-water lateral advection and near bottom nepheloid input. The spreading to the east and to the south of phytoplankton-rich water from the upwelling off the Spanish coast is controlled by the position and size of the Western and Eastern Alboran gyres, and drives the seasonal arrival of biogenic material down to the sea floor. Discrete lateral advection events unrelated to vertical entries of material can also supply particulate matter at 1000–1200 and 2000–2200 m of water depth as noted at the northern and southern stations. To achieve a better understanding of the carbon cycle in the area we have attempted to constrain the production, transfer and burial of particulate organic carbon, providing the first estimates of particulate organic carbon export in the Alboran Sea. Results suggest that sea surface circulation and associated productivity signal control the efficiency of the biological pump in the area. The export production in the Eastern Alboran Sea is higher than in other Mediterranean sites, with 0.5–0.9% of the carbon fixed during photosynthesis transferred down the water column and buried in the deep sediments. In addition, a large portion is supplied by lateral advection and through a benthic nepheloid layer, which represent a significant source of organic carbon to the deep Eastern Alboran Sea.

Particulate biogenic barium (bio-Ba) fluxes obtained from three instrumented arrays moored in the Alboran Sea, the westernmost basin in the Mediterranean Sea, are presented in this study. The mooring lines were deployed over almost 1 year, from July 1997 to May 1998, and were equipped with sediment traps at ∼500–700 m depth, ∼1000–1200 m depth and 30 m above the seafloor (∼1000–2200 m). The results obtained support the growing body of evidence that the relationship between particulate bio-Ba and Corg throughout the water column in margin systems is clearly different from this relation in the open ocean. In the Alboran Sea, the annual averaged bio-Ba fluxes range from 0.39 to 1.07 μmol m−2 day−1, with mean concentrations of 1.31–1.69 μmol g−1 and bio-Ba/Corg ratios lower than in the open ocean. The low bio-Ba values obtained also indicate that calculating bio-Ba is extremely sensitive to the detrital Ba/Al ratio of each sample. The lithogenic Ba fraction in the Alboran Sea continental margin area contributes between 24% and 85% of the total Ba. Increased bio-Ba export efficiency was observed after periods of high primary productivity and suggests that the processes limiting the bio-Ba formation in the study area relate to settling dynamics of organic matter aggregates. Furthermore, the ballasting effect of the abundant lithogenic and carbonate particles may limit decomposition of organic matter aggregates and enhance the transfer of particles rich in Corg and relatively poor in bio-Ba to the deep seafloor. Lateral input of freshly sedimented biogenic material, including particulate bio-Ba, has been observed on the lower continental slope in the western Alboran Sea. These observations emphasize that the use of the bio-Ba as a proxy of export productivity from the surface ocean must be used cautiously in highly dynamic environments such as those in the Alboran Sea.

Particle flux data were obtained from one instrumented array moored under the direct influence of the Almeria-Oran Front (AOF) in the Eastern Alboran Sea, Western Mediterranean Sea, within the frame of the “Mediterranean Targeted Project II-MAss Transfer and Ecosystem Response” (MTPII-MATER) EU-funded research project. The mooring line was deployed from July 1997 to May 1998, and was equipped with three sequential sampling sediment trap-current meter pairs at 645, 1170 and 2210 m (30 m above the seafloor). The settling material was analysed to obtain total mass, organic carbon, opal, calcium carbonate and lithogenic fluxes. Qualitative analyses of SST and SeaWiFS images allowed monitoring the location and development of the Western and Eastern Alboran Sea gyres and associated frontal systems to determine their influence on particle fluxes. Particle flux time series obtained at the three depths showed a downward decrease of the time-weighed total mass flux annual means, thus illustrating the role of pelagic particle settling. The total mass flux was dominated by the lithogenic fraction followed by calcium carbonate, opal and organic carbon. The time series at the various depths were rather similar, with two strong synchronous biogenic peaks (up to 98 mg m −2 day −1 of organic carbon and 156 mg m −2 day −1 of opal) recorded in July 1997 and May 1998. Through comparing the fluctuations of the lithogenic and calcium carbonate-rich fluxes with the biogenic flux, we observed that the non-biogenic fluxes remained roughly constant, while the biogenic flux responded strongly to seasonal variations throughout the water column. Overall, the temporal variability of particle fluxes appeared to be linked to the evolution of several tens of kilometres in length sea surface hydrological structures and circulation of the Alboran Sea. Periodic southeastward advective displacements of waters from upwelling events off the southern Spanish coast were observed on SST and SeaWiFS images. In between these periods, widespread phytoplankton blooms were observed. The influence of the varying surface structures resulted in changes in the biogenic particle flux. For example, we observed an opal pulse in April 1998 that resulted from a diatom-rich highly productive frontal surface situation above the mooring line. Estimation of the annual organic carbon export and calculation of a seasonality index indicate that the overall dynamics of the carbon reservoir within the Eastern Alboran Sea appears to be strongly influenced by the sea surface hydrological structures.

From October 2005 through October 2006 sediment traps were moored along the Lacaze–Duthiers and Cap de Creus submarine canyons and on the adjacent southern open slope in the Gulf of Lion (Northwestern Mediterranean). During the Winter 2006 (January–March), an intense Dense Shelf Water Cascading (DSWC) event was found to be a major driver of particle transport, increasing lateral advection of material at all stations. In this study, we assessed the sources and degradation of organic matter (OM) advected along canyons during both DSWC and quiescent conditions using specific organic biomarkers, including pigments, lignin phenols and amino acids. Three major events of fresh, marine OM inputs were detected during the study period. The largest one was in spring (March–May), with smaller events also observed in winter (December 2005) and summer (August 2006), suggesting that both spring blooms and sporadic blooms associated with wind-driven mixing affects carbon fluxes in this system. The DSWC event that partially overlapped the spring-bloom enhanced the overall transfer of OM down canyons. The lignin phenol data show no significant, along-canyon dilution and are consistent with constant advection of terrigenous material. In contrast, amino acid and chloropigment compositions indicate that part of the OM is degraded both prior to reaching the canyons and within the canyons themselves. Overall, our results illustrate the importance of both seasonal and sporadic pelagic and continental shelf/lateral events in controlling the exchange of organic matter across this margin.

The accumulation rates of sediment and major constituents in three different geographic areas of the Alboran Sea have been assessed by means of 210Pb and 137Cs concentration profiles. Mixing is present in the top layer of the sedimentary column, with mixing coefficients estimated to range from 0.2 to 15 cm2 yr−1. Overall, apparent sedimentation rates for the last 100 years range from 0.014 to 0.182 g cm−2 yr−1 and show a tendency to decrease with distance to the coast and water column depth. However, specific characteristics of the sea floor for each physiographic environment govern the actual patterns of sediment accumulation. Particularly noticeable are the feeding role of submarine canyons, the trapping effect of slope terraces and the isolation caused by ridges. Sediment accumulation induced by turbiditic flows is also observed north of the Almeria–Oran area. Excess 210Pb inventories and surface concentrations reveal a net effect of sediment focussing and point to the role of bottom nepheloid layers in supplying a significant fraction of sediments to the deep areas. This is also evidenced by comparison of bottom sediment with the sediment trap data available from the Malaga area. We estimate that the particle advective input below 30 m above the bottom accounts for as much as 50–70% of the material that is ultimately deposited onto the sea floor. The greater abundance of lithogenic material in the Malaga zone (∼80%) reflects its larger input in the western Alboran Sea. Conversely, carbonate contents increase from less than 20% in this area to about 30% in the Almeria–Oran zone, reflecting the lesser importance of the dilution by lithogenic components. Biogenic silica was only detected in some surface samples, and no significant preservation was observed below the Eh boundary. Abundance and accumulation rates of organic matter are in accordance with the spatial patterns of primary production in the Alboran Sea: higher in the western part, due to the presence of the Western Alboran Gyre. However, near-bottom redistribution leads to the homogenisation of organic matter concentrations in bottom sediments of any given area. Finally, from comparisons with sediment trap data, the degradation of organic matter has been estimated to be approximately 30–40% of what reaches the bottom.

Total mass and main constituents (carbonate, organic matter, biogenic opal and lithogenic fraction) flux series were obtained in the northern part of the Western Alboran Gyre during an annual cycle from July 1997 to May 1998, at 10 days sampling interval. Two mooring lines equipped with sediment trap–current meter pairs were deployed across the continental slope off Malaga. CTD, SeaWiFS and watershed fluvial discharge data sets were also obtained from several sources to establish their relations with particle flux data. Time-averaged fluxes for the whole period, including fluxes of organic carbon, increased slightly with depth in both locations as the result of the input of particulate matter by near-bottom nepheloid layers. Furthermore, time-averaged fluxes at mid waters were higher in the centre of the gyre than at its periphery, suggesting some kind of particle funnelling from the gyre periphery towards its centre. Temporal evolution of fluxes was highly variable throughout the year. All series showed an overall common evolution with a first peak at the beginning of summer 1997, a second broad composite peak during late autumn/winter and a third one in spring 1998. Composition of settling particles showed that summer and spring peaks were richer in biogenic constituents compared to the late autumn/winter peak. Particle fluxes to mid water depths in the northern part of the Alboran Sea seem to be mainly controlled by fluvial discharge and primary production. Fluvial discharge could be responsible for the higher lithogenic flux during autumn and winter, while high primary production could play a key role in generating biogenic particles during spring and summer. Regarding near-bottom fluxes, the temporal evolution was controlled both by the downward transfer of particulate matter from mid waters and the advective input of mostly lithogenic and carbonate matter. The increased advective input during maximum near-bottom fluxes is tentatively related to intense eddy-like activity recorded in the deep-water masses.

13 pages, 9 figures, We present a 1-yr (2005-2006) record of organic carbon (OC) and total nitrogen (TN) contents and their isotopic ratios (δ13Coc and δ15N) in sinking particles from the western Gulf of Lions. Maximum OC and TN fluxes recorded in January 2006 and March-April 2006 were associated with negative near-bottom temperature anomalies. This reveals large inputs of resuspended organic matter from the shelf basinwards to depths > 1500 m by dense shelf-water cascading. The first pulse of organic matter had low δ13Coc (-25.5%0) and N: C (0.08) and high δ15N (6.6%0) values, indicative of the arrival of organic matter of terrestrial origin. In contrast, the second pulse had high δ13Coc (-21.9%0) and N: C (0.15) and extremely low δ15N (0.0%0) values, indicative of the transfer of organic matter with higher marine contribution. Though downslope export of organic matter from the adjacent shelf predominated, particles escaping from surface waters remained an important source of organic matter during low-energy and low-flux periods and especially during summer conditions, with significant contribution of N2 fixation to organic matter export. Overall, our results suggest the export of organic matter from different sources to the deep Mediterranean basin, which in turn might alter within a couple of months the quality of the sedimentary organic matter deposited on the sea floor and thus the dynamics of the deep ecosystems. © 2009, by the American Society of Limnology and Oceanography, Inc, This research has been supported by a Marie Curie Individual Fellowship (re. MEIF-CT-2006-024068) to A. Sanchez-Vidal, the research projects Hotspot Ecosystem Research on the Margins of European Seas (ref. GOCE-CT-2005-511234-1), Southern European Seas: Assessing and Modelling Ecosystem Changes (ref. GOCE-036949), Estudio Integrado de Cañones y Taludes Profundos del Mediterráneo Occidental: un hábitat esencial (ref. CTM2007-66316-C02-01/MAR), Multidisciplinary Research Consortium on Gradual and Abrupt Climate Changes, and Their Impacts on the Environment (ref. CSD2007-00067, Consolider Ingenio 2010 Program), and a Generalitat de Catalunya ‘‘Grups de Recerca Consolidats’’ grant (2005 SGR-00152)

International audience

Marine debris, mostly consisting of plastic, is a global problem, negatively impacting wildlife, tourism and shipping. However, despite the durability of plastic, and the exponential increase in its production, monitoring data show limited evidence of concomitant increasing concentrations in marine habitats. There appears to be a considerable proportion of the manufactured plastic that is unaccounted for in surveys tracking the fate of environmental plastics. Even the discovery of widespread accumulation of microscopic fragments (microplastics) in oceanic gyres and shallow water sediments is unable to explain the missing fraction. Here, we show that deep-sea sediments are a likely sink for microplastics. Microplastic, in the form of fibres, was up to four orders of magnitude more abundant (per unit volume) in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean than in contaminated sea-surface waters. Our results show evidence for a large and hitherto unknown repository of microplastics. The dominance of microfibres points to a previously underreported and unsampled plastic fraction. Given the vastness of the deep sea and the prevalence of microplastics at all sites we investigated, the deep-sea floor appears to provide an answer to the question— where is all the plastic?

International audience; In this study, we investigate the strength and efficiency of carbon sequestration in the Southern European Seas (SES), by analyzing the export of POC at three deep sites located in the Western Mediterranean Sea (WMED), the Eastern Mediterranean Sea (EMED) and the Black Sea (BS). We combine estimations of satellite and algorithm-generated primary production data, calculated POC fluxes out of the euphotic layer and POC fluxes measured by sediment traps at the mesopelagic and bathypelagic layers during a one year period, with an ultimate goal to obtain a better understanding of the functioning of the biological pump in the SES.Annual particulate primary production based on satellite estimations (SeaWiFS) at the three sites, averages 205, 145 and 225 gC m− 2 y− 1 at the WMED, EMED and BS, respectively. According to our findings, the fraction of primary production that is exported out of the euphotic zone in the SES ranges between 4.2% and 11.4%, while the fraction reaching the mesopelagic layer (1000–1400 m depth) ranges between 0.6% and 1.8%. Finally, the fraction of primary production exported at the bathypelagic layer (2000–2800 m depth) is found to be 0.6%, 0.3% and 1.4% in the WMED, EMED and BS, respectively. The role of various processes responsible for the replenishment of surface waters with nutrients, giving rise to productivity episodes and organic carbon export to depth at the three SES sites is considered.

In the frame of the EU-funded ADIOS project, the aim of this paper is to present the results of the total mass and the major constituent (organic matter, calcium carbonate, opal and lithogenics) fluxes obtained in the central part of the Algero–Balearic Basin (ABB). Two identical mooring lines, named A and B were equipped with three automated sediment traps and three current meters at 250 m, 1440 m and 2820 m of water depth, and another one, named C, was equipped with five sediment trap–current meter pairs at the corresponding depths of 250 m, 845 m, 1440 m, 2145 m and 2820 m. The samples were collected during an annual period, from April 2001 to May 2002 over sampling periods of 15–30 days. The presented particle fluxes data constitute the first one-year experimental study carried out in the open ABB, a region in which the continental inputs are expected to be minimums. This fact explains why the values of the mean annual fluxes were the lowest found in the whole Western Mediterranean Sea, ranging from 11.30 mg·m − 2 day − 1 (2145 m; station C) to 112.75 mg m − 2 day − 1 (250 m; station A). The temporal evolution of the particle fluxes in the upper waters shows the dominance of the atmospherically derived particles during summer and autumn, and a clear biological control during winter related to the primary productivity pathway. Along the whole water column, the calcium carbonate appears as the main relative contributor of the biogenic material (26%–30%), and the opal content presents the lowest values (6%–8%), suggesting that the study area is a carbonate-dominated ecosystem. Otherwise, even if the particles are derived from the atmosphere or internally produced by biological processes, it is clear that their transference from the upper to the deeper ocean is controlled by the stabilization of the water column and the distribution of the water masses in the Western Mediterranean Sea. In this context, the input of the Tyrrhenian Deep Water (TDW) into the AB7B at 800–1500 m of water depth strongly affects the distribution of the particle fluxes in the basin, being responsible of the minimum concentration zone at intermediate depths. Furthermore, current meter and flux data indicate a high influence of the Gulf of Lions water mass formation by spreading of dense cold water along the whole ABB, leading up to a maximum of particulate matter at depths higher than 2000 m.

Special issue Integrated study of a deep submarine canyon and adjacent open slopes in the Western Mediterranean Sea: an essential habitat.-- 13 pages, 7 figures, 2 tables, To characterize the temporal and spatial variability of total mass fluxes in the Blanes submarine canyon and the nearby southern open slope, eight near-bottom sediment traps were deployed at 300, 900, 1200 and 1500m along the canyon axis, and at 900, 1200, 1500 and 1800m of water depth on the southern open slope from November 2008 to November 2009. The results obtained show that mass fluxes were higher into the canyon, ranging from 0.05 to 82.67gm-2d-1, compared with those from the open slope that ranged from 0.01 to 9.91gm2d-1. Both environments were highly influenced by atmospheric forcing and showed increased total mass fluxes during autumn and winter months. The spatial distribution of total mass fluxes and major constituents (organic matter, carbonate, opal and lithogenics) highlights the contrasts amongst the two physiographic domains in the study area (canyons vs. open slope). The temporal evolution of particle fluxes shows three distinct situations succeeding each other along the year. These are determined by: (1) storms in autumn and winter, driving 60% of the annual total mass flux in Blanes Canyon and 44% in the open slope stations, and also 60% and 40% of the annual OC flux in Blanes Canyon and the southern open slope, respectively; (2) open sea convection in late winter and spring, which is accompanied by a phytoplankton bloom and drives 13% of the settling OC in the canyon and 34% in the open slope; and (3) dust inputs and resuspension by bottom trawling in late spring and -summer months, driving 17% of the annual OC flux in the canyon and 18% in the slope. © 2013 Elsevier Ltd., This research has been supported by Spanish and EU funded projects PROMETEO (CTM2007-66316-C02-01/MAR), DOS MARES (CTM2010-21810-C03-01), GRACCIE-CONSOLIDER (CSD2007-00067), PERSEUS (GA 287600) and REDECO (CTM2008-04973-E/MAR) RTD projects. University of Barcelona researchers are supported by grant 2009 SGR 1305 of Generalitat de Catalunya. P.L.F. benefited from a Spanish FPI Grant (BES-2008-009374)

Special issue Integrated study of a deep submarine canyon and adjacent open slopes in the Western Mediterranean Sea: an essential habitat.-- 13 pages, 10 figures, 3 tables, Temporal patterns in deep-sea fish reproduction are presently unknown for the majority of deep continental margins. A series of seasonal trawling surveys between depths of 300 to 1750. m in the Blanes submarine canyon and its adjacent open slope (NW Mediterranean) were conducted. The bathymetric size distributions and reproductive cycles of the most abundant species along the NW Mediterranean margin were analyzed to assess the occurrence of (i) temporal patterns in reproduction (i.e., spawning season) along a bathymetric gradient and (ii) preferential depth strata for recruitment. The fish assemblages were grouped in relation to their bathymetric distribution: upper slope, middle slope and lower slope species. Middle-slope species (i.e., 800-1350. m) showed short (i.e., highly seasonal) reproductive activity compared to the upper (300-800. m) and lower (1350-1750. m) ones. Our results, together with those previously published for megabenthic crustacean decapods in the area, suggest a cross-phyla depth-related trend of seasonality in reproduction. In the middle and lower slope species, the reproductive activity reached a maximum in the autumn-winter months and decreased in the spring. The observed seasonal spawning patterns appear to be ultimately correlated with changes in the downward transport of organic particles and with seasonal changes in the physicochemical characteristics of the surrounding water masses. The distribution of juveniles was associated with the bathymetric stratum where intermediate nepheloid layers interact with the continental margins, indicating that this stratum acts as a deep-sea fish nursery area. © 2013 Elsevier Ltd., This study was conducted within the framework of the RECSII, PROMETEO and DOSMARES projects by the Spanish Science and Innovation Agency (REN02/04556/C02/MAR; CTM2007-66316-C02/MAR; CTM2010-21810-C03-03/MAR respectively, to JBC) and European Community’s Seventh Framework Program under the HERMIONE project (Grant Agreement 226354, to ERLL). UF-A is funded by a Spanish doctoral fellowship FPI-2008. ERLL is funded by a Spanish JAE-CSIC postdoctoral grant with co-funding of the European Social Fund

With the aim of improving the knowledge of the open ocean carbon cycle, we present a budget of particulate organic carbon (POC) fluxes carried out in the deep central part of the Algero-Balearic Basin (ABB) at 2850 m water depth based on a single mooring equipped with five automated sediment traps deployed from April 2001 to May 2002 at depths of 250, 845, 1440, 2145 and 2820 m. Suspended particulate matter (SPM) and superficial sediments were also used as indicators of hydrodynamics and carbon burial, respectively. The data reveal that the fraction of primary production buried in the sediment, which finally leads to the sequestration of carbon dioxide from the atmosphere, is 0.16%, lower than the values found in the nearby continental margin regions such as the Alboran Sea (0.48–0.89%) but of the same order as recorded at other Mediterranean sites at similar depths, such as the Ionian Sea (0.11%). As they sink through the water column, the particles exhibit decreases in flux that are similar to those observed elsewhere, but also show variations that appear to correlate with hydrological features of the water masses present in the basin, as revealed by SPM concentrations and compositions. The input of the tyrrhenian deep water (TDW) into the ABB at 800–1500 m of water depth exhibits low suspended POC concentrations and low sinking POC fluxes were also observed in this depth range. Gulf of Lions water mass formation appears to also contribute to elevated suspended POC concentrations and perhaps POC accumulation in the traps and sediments by spreading of dense cold water along the whole ABB that supplied POC at depths higher than 2000 m.

A large amount of terrestrial organic matter is annually delivered by rivers to the continental shelf, where this material is either buried or transferred to the deep sea by hydrodynamic processes such as storms. The relative amount of terrestrial organic matter in the marine sediments is often determined by analyzing the stable isotopes (δ13C and δ15N) and the C / N ratio of organic matter because the various particulate organic matter (POM) sources have distinct isotopic compositions. With the objective to refine and better interpret POM sources in the marine environment, we have monthly characterized terrestrial POM delivered by eight rivers discharging to the NW Mediterranean Sea: Rhône, Hérault, Orb, Aude, Têt, Fluvià, Ter and Tordera rivers. These rivers were simultaneously sampled from November 2008 to December 2009 and the concentrations of total suspended matter (TSM), particulate organic carbon (POC) and nitrogen (PN), as well as their stable isotopic ratios (δ13C and δ15N) were determined. During the survey, three rainstorm events with winds coming from the E–NE and the S–SE impacted the NW Mediterranean. Depending on the direction of incoming winds, the fluvial response (amount of water discharge and TSM) was different. Rivers draining the Alps (Rhône River) and Central Massif (Hérault, Orb, and Aude rivers) were mostly impacted by rainstorms associated with winds coming from the S–SE, while rivers draining the Pyrenees (Têt, Fluvià, and Ter rivers) and the Montseny Massif (Tordera River) were impacted by rainstorms associated with winds coming from the E–NE. In addition, the spatial evolution of water discharges shows different hydrological regime of the Rhône River, with relatively constant and high water stages and TSM concentrations when compared to coastal rivers, characterized by long periods of low water stages. TSM concentrations are positively correlated to water discharges (high water flows resuspended riverbed sediments) but show an inverse relationship with POC and PN relative contents (mostly due to dilution and by low availability of light in river waters during flood events). TSM in most of the coastal rivers have in average 2.5–3 times higher POC and PN mean contents than the Rhône River (8.5% and 1.5%, respectively for coastal rivers against 3.6% and 0.5%, respectively for the Rhône River). This discrepancy may be caused by the long drought periods in small coastal Mediterranean watersheds that enhance the eutrophication in studied coastal rivers. The δ13C ratios of organic matter reflect also this discrepancy between high and low water stages with values ranging from −33.2‰ to −24.5‰. The enriched 13C values (−26.3 ± 0.4‰ for the Rhône River and −26.9 ± 1.2‰ for coastal rivers), measured during high water stages, express mostly a mixture of terrestrial source (plant remains and soils) whereas depleted 13C values (∼ −30‰) associated with low water stages exhibit a source with predominant freshwater algae. The high δ15N mean values (> 8‰) found in Têt, Ter and Tordera rivers underline the importance of denitrification processes as a consequence of the eutrophication and anthropogenic impact.

International audience; The winter of 2012 experienced peculiar atmospheric conditions that triggered a massive formation of dense water on the continental shelf and in the deep basin of the Gulf of Lions. Multi-platforms observations enabled, with an unprecedented resolution, a synoptic view of dense water formation and spreading at basin scale. Five months after its formation, the dense water of coastal origin created a distinct bottom layer up to few hundreds of meters thick over the central part of the NW Mediterranean basin, which was overlaid by a layer of newly formed deep water produced by open-sea convection. These observations highlight the role of intense episodes of both dense shelf water cascading and open-sea convection to the alteration of the characteristics of the NW Mediterranean deep waters.

Martín, Jacobo ...et al. -- 19 pages, 12 figures, Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of the mild and wet 2010–2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed for the study of the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms (maximum significant wave heights = 4.1–4.6 m). During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of the CCC in an approximate depth range of 150–350 m. The density of this water mass was lighter than the ambient water in the canyon, indicating that it did not cascade off-shelf and that it merely downwelled into the canyon forced by the strong cyclonic circulation induced over the shelf during the storms and by the subsequent accumulation of seawater along the coast. Suspended sediment load in this turbid intrusion recorded along the southern canyon flank oscillated between 10 and 50 mg L−1, and maximum currents speeds reached values up to 90 cm s−1. A rough estimation of 105 tons of sediment was transported through the canyon along its southern wall during a 3-day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down- to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated with eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200–300 m above the bottom. Our paper broadens the understanding of the complex set of atmosphere-driven sediment transport processes acting in this highly dynamic area of the northwestern Mediterranean Sea, We are grateful to the crew and officials of R/V l’Atalante and to all the scientific and technical staff involved in the CASCADE cruise. This work was funded by the HERMIONE Project (FP7-ENV-2008-1-226354) under the European Commission’s Seventh Framework Programme, the French programme MERMEX under the MISTRALS framework, the GRACCIE-CONSOLIDER project (CSD2007-00067) and the Spanish project DOS MARES (CTM2010-21810-C03-01). University of Barcelona researchers benefitted from grant 2009 SGR 1305 by Generalitat de Catalunya to excellence research groups. L. Houpert acknowledges the support of the Direction Générale de l’Armement (supervisor: Elisabeth Gibert-Brunet). J. Martín was funded through a JAE-DOC contract within the programme “Junta para la Ampliación de Estudios”, granted by Consejo Superior de Investigaciones Científicas (Spain) and co-financed by the European Social Fund. We thank the constructive comments of two reviewers who helped to improve the manuscript

International audience; The winter of 2012 experienced peculiar atmospheric conditions that triggered a massive formation of dense water on the continental shelf and in the deep basin of the Gulf of Lions. Multiplatforms observations enabled a synoptic view of dense water formation and spreading at basin scale. Five months after its formation, the dense water of coastal origin created a distinct bottom layer up to a few hundreds of meters thick over the central part of the NW Mediterranean basin, which was overlaid by a layer of newly formed deep water produced by open-sea convection. These new observations highlight the role of intense episodes of both dense shelf water cascading and open-sea convection to the progressive modification of the NW Mediterranean deep waters.

10 pages, 7 figures, 1 table, It is generally assumed that episodic nutrient pulses by cyclonic eddies into surface waters support a significant fraction of the primary production in subtropical low-nutrient environments in the northern hemisphere. However, contradictory results related to the influence of eddies on particulate organic carbon (POC) export have been reported. As a step toward understanding the complex mechanisms that control export of material within eddies, we present here results from a sediment trap mooring deployed within the path of cyclonic eddies generated near the Canary Islands over a 1.5-year period. We find that, during summer and autumn (when surface stratification is stronger, eddies are more intense, and a relative enrichment in CaCO3 forming organisms occurs), POC export to the deep ocean was 2-4 times higher than observed for the rest of the year. On the contrary, during winter and spring (when mixing is strongest and the seasonal phytoplankton bloom occurs), no significant enhancement of POC export associated with eddies was observed. Our biomarker results suggest that a large fraction of the material exported from surface waters during the late-winter bloom is either recycled in the mesopelagic zone or bypassed by migrant zooplankton to the deep scattering layer, where it would disaggregate to smaller particles or be excreted as dissolved organic carbon. Cyclonic eddies, however, would enhance carbon export below 1000 m depth during the summer stratification period, when eddies are more intense and frequent, highlighting the important role of eddies and their different biological communities on the regional carbon cycle. © 2013 Alonso-González et al., This work was funded through the Spanish “Plan Nacional de I+D” under the RODA (CTM2004-06842-C03-03/MAR), PUMP (CMT2012-33355) and HOTMIX (CTM2011-30010-C02-01) projects. A.S-V. and A.C. acknowledge a Generalitat de Catalunya “Grups de Recerca Consolidats” grant (2009 SGR-1305). The ROMS model configuration was developed at UCLA, where ROMS development is supported by the Office of Naval Research (currently grant N00014-08-1-0597). The ROMS work was partially supported by the National Center for Supercomputing Applications under the grant number OCE030007 and utilized the abe system

Submarine canyons are sites of intense energy and material exchange between the shelf and the deep adjacent basins. To test the hypothesis that active submarine canyons represent preferential conduits of available food for the deep-sea benthos, two mooring lines were deployed at 1200 m depth from November 2008 to November 2009 inside the Blanes canyon and on the adjacent open slope (Catalan Margin, NW Mediterranean Sea). We investigated the fluxes, biochemical composition and food quality of sinking organic carbon (OC). OC fluxes in the canyon and the open slope varied among sampling periods, though not onsistently in the two sites. In particular, while in the open slope the highest OC fluxes were observed in August 2009, in the canyon the highest OC fluxes occurred in AprilMay 2009. For almost the entire study period, the OC fluxes in the canyon were significantly higher than those in the open slope, whereas OC contents of sinking particles collected in the open slope were consistently higher than those in the canyon. This result confirms that submarine canyons are effective conveyors of OC to the deep sea. Particles transferred to the deep sea floor through the canyons are predominantly of inorganic origin, significantly higher than that reaching the open slope at a similar water depth. Using multivariate statistical tests, two major clusters of sampling periods were identified: one in the canyon that grouped trap samples collected in December 2008, oncurrently with the occurrence of a major storm at the sea surface, and associated with increased fluxes of nutritionally available particles from the upper shelf. Another cluster grouped samples from both the canyon and the open slope collected in March 2009, concurrently with the occurrence of the seasonal phytoplankton bloom at the sea surface, and associated with increased fluxes of total phytopigments. Our results confirm the key ecological role of submarine canyons for the functioning of deep-sea ecosystems, and highlight the importance of canyons in linking episodic storms and primary production occurring at the sea surface to the deep sea floor.

Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the deep basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of a mild and wet 2010–2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed to study the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms of significant wave heights = 4–4.5 m. During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of CCC in an approximate depth range of 150–350 m. The density of this water mass only reached ~ 28.78 kg m−3, indicating that it did not cascade into the canyon and that merely downwelled into it forced by the accumulation of seawater along the coast during the storms and by the subsequent strong cyclonic circulation induced over the shelf. Suspended sediment load in this turbid intrusion was comparable at three heights above bottom where turbidimeters were installed (10, 75 and 115 m above bottom) on the southern canyon flank and oscillated between 10 and 50 mg L−1. Current speeds were also comparable in the depth range profiled by ADCPs (40 to 150 mab) and reached values up to 90 cm s−1 during the peak of the strongest storm (13 March, Hs = 4.5 m). Sediment transport at 75 mab on the southern canyon flank was estimated at 1–1.5 t m−2 for the entire deployment while very close to the bottom (5 m above) in the canyon head it was less than 0.6 t m−2 during the same period. We provide a rough estimation of 105 t of sediment transported through the canyon along its southern wall during a 3 day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated to eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200–300 m above the bottom. Our paper broadens the understanding of the complex set of atmosphere-driven sediment transport processes acting in this highly dynamic area of the northwestern Mediterranean Sea.

International audience; Surface sediments collected from deep basins (1018-4087 m depth) of the eastern Mediterranean Sea (Ionian Sea, southern Aegean Sea and northwestern Levantine Sea) were analyzed for aliphatic and polycyclic aromatic hydrocarbons as tracers of natural and anthropogenic inputs. Concentrations of total aliphatic hydrocarbons, n-alkanes and the unresolved complex mixture (UCM) of aliphatic hydrocarbons varied significantly, ranging from 1.34 to 49.2 μg g-1, 145 to 4810 ng g-1 and 0.73 to 36.7 μg g-1, respectively, while concentrations of total polycyclic aromatic hydrocarbons (PAHs) ranged between 11.6 and 223 ng g-1. Molecular profiles of determined hydrocarbons reflect a mixed contribution from both natural and anthropogenic sources in deep-sea sediments of the eastern Mediterranean Sea, i.e., terrestrial plant waxes, degraded petroleum products, unburned fossil fuels and combustion of grass, wood and coal. Hydrocarbon mixtures display significant variability amongst sub-regions, reflecting differences in the relative importance of inputs from various sources and phase associations/transport pathways of individual hydrocarbons that impact on their overall distribution and fate. Hydrocarbon concentrations correlated significantly with the organic carbon content of sediments, indicating that the latter exerts an important control on their transport and ultimate accumulation in deep basins. Additionally, water masses' circulation characteristics also seem to influence the regional features and distribution patterns of hydrocarbons. Our findings highlight the role of deep basins/canyons as repositories of both natural and anthropogenic chemical species.

Submarine canyons of several regions of the world are preferential conduits for Dense Shelf Water Cascading (DSWC), which quickly modify physical and chemical conditions while transporting large amounts of material towards the adjacent deep margin. Observations conducted during the last 15 yr in the Cap de Creus Canyon (Gulf of Lion, NW Mediterranean Sea) reported several intense events of DSWC. Their effects on the deep-sea biodiversity and ecosystem functioning are almost unknown. To investigate the effects of these episodic events we analysed changes in the meiofaunal biodiversity inside and outside the canyon. Sediment samples were collected at depths varying from ca. 1000 to > 2100 m in May 2004 (before a major event), April 2005 (during a major cascading event) and in October 2005, August 2006 April 2008 and April 2009. We report here that the late winter-early spring 2005 cascading led to a reduction of the organic matter contents in canyon floor sediments down to 1800 m depth, whereas surface sediments at about 2200 m depth showed an increase. Our findings suggest that the nutritional material removed from the shallower continental shelf open slope and canyon was transported to the deep margin. During the cascading event the meiofaunal abundance and biodiversity in the studied deep-sea sediments dropped down by a factor of 5 to 10. Benthic assemblages in the impacted seafloor recovered to pre-cascading conditions after only six months from the cessation of the cascading. Since the present climate change is expected to increase the intensity and frequency of these episodic events, we anticipate that they will increasingly impact biodiversity and functioning of the benthic bathyal ecosystems, which may eventually challenge their resilience.

One recurrent antecedent of women's discrimination at work is their remaining trade-offs between career and domestic responsibilities. This is directly related to male employees' and managers' limi...

International audience; In the Black Sea, downward fluxes of biogenic elements in the water column were monitored during a 1 yr (2007-2008) sediment trap deployment in the SW basin (at 1000 and 2000 m water depth) aiming at appraising their amplitude, seasonal variability and prime controlling factors, and thus better assessing the biogeochemical functioning of this environment. Particulate organic carbon (POC) and carbonate fluxes display a strong seasonal pattern, with peak values in late autumn (POC) and early summer (carbonates). Mean POC fluxes at 1000 and 2000 m were 11.3 and 6 mg/m2/d, respectively, corresponding to 1.8 and 1 % of the estimated primary production. We used source-specific lipid biomarkers in order to determine the major phytoplankton contributors to the biogenic fluxes, as well as terrestrial organic inputs, and to shed light into the composition and variability of the biological system. These molecular data clearly demonstrate that diatoms (in particular Rhizosolenia species) are foremost drivers of the peak POC flux in late autumn. As expected, diatom productivity is also closely related with the patterns of the export opal fluxes. Furthermore, biomarkers document a major bloom of Emiliania Huxleyi in late spring/early summer, likely sustained by riverine nutrient inputs and/or regenerated nutrients. However, POC export is less strong during the coccolithophorid bloom. In contract, this bloom controls the unique peak value of carbonate flux. Dinoflagellate-specific biomarkers reveal a less prominent seasonal pattern, with higher values in late autumn and summer. In all the aforementioned periods biomarker tracers also evidence that zooplankton (and its fecal pellets) are important constituents of the export POC flux. As for the terrestrial inputs, they are mostly characterized by a high peak in late spring/early summer, when enhanced riverine discharges occur. Our findings demonstrate that the export of biogenic elements is closely linked to the structure of the biological system. The latter is largely controlled by hydrological features (physical forcing). The absence of a "typical" spring bloom, in line with historical data since the mid 90's, reflects the impact of warming and associated limited nutrient supply into surface waters due to weaker mixing during mild winters. Instead, diatoms bloom rather in autumn with a strong phase in November. Increased stratification with a shallow mixing zone and most favorable light and temperature conditions lead to a strong coccolithophorid bloom in early summer (overlooked by satellite Chl assessments). We further compare our findings with available in-situ and satellite data and with a coupled physical-biogeochemical model in order to progress in our understanding of the dynamics of export biogenic fluxes in the Black Sea and its links with the biological community structure, the biogeochemical functioning of the Black Sea system and environmental changes.

I risultati di una ricerca empirica condotta su un campione di 8.937 imprese italiane non quotate e 58.548 osservazioni annue relative al periodo 1996-2005 mostrano che la detenzione di liquidità da parte delle imprese Italiane non quotate supporta sia il modello del trade-off sia la teoria della gerarchia finanziaria. Infatti, la liquidità è detenuta in misura maggiore dalle imprese più rischiose e dalle imprese con maggiori prospettive di crescita. Allo stesso tempo, detengono più liquidità le imprese caratterizzate da cicli finanziari più lunghi e da minori deficit finanziari, come predetto dalla teoria dell’ordine di scelta. L’evidenza raccolta mostra anche che le imprese non quotate che distribuiscono dividendi detengono maggiore liquidità, che la liquidità può essere considerata come un debito negativo e che il capitale circolante netto rappresenta un buon sostituto del debito. Sembra inoltre che le imprese con maggiori riserve di liquidità facciano più investimenti in un orizzonte successivo di diversi anni. Una ripartizione geografica delle imprese italiane nelle tre macroaree, Nord, Centro e Sud, ha inoltre evidenziato qualche differenza significativa circa il livello di liquidità detenuto e l’effetto di alcune variabili.