NW Mediterranean Basin Research Articles

The cold-water coral province of the eastern Ligurian Sea (NW Mediterranean Sea): historical and novel evidences

Several bathyal cold-water coral provinces, characterized by a lush growth of habitat-forming scleractinians, have been recognized in the Mediterranean Sea. However, the search for this biogenic habitat only marginally targeted the Italian coast of the Ligurian Sea (NW Mediterranean basin) despite historical and a few recent local studies in the region reporting the presence of corals. This study used bathymetry maps, side-scan sonar profiles, historical charts, and trawling routes to identify sites that could potentially host coral habitats in the eastern sector of the Ligurian Sea. Remotely operated vehicle video footage from various projects (2015-2021, 20 dives) was then used to characterize four sub-areas (Genoa Plateau, Portofino, Deiva Marina, and Monterosso) where corals were detected between 450 m and 750 m depth. Radiocarbon dating was used to trace back the geological history of the coral structures. A small coral mound, impacted by trawling activities, was found on the Genoa Plateau, while four massive coral structures were found in the other sub-areas, mainly located in a morphologically complex and highly energetic canyon region. High levels of megafaunal biodiversity, including rarely reported alcyonaceans as Placogorgia coronata, were observed together with moderate fishing impact. Overall, the identified coral areas potentially account for 9 km2 of both subfossil mounds (as old as 13300 years BP), dominated by Desmophyllum pertusum, and living reefs, dominated by Madrepora oculata, the latter representing up to 23% of the substrate coverage. The few living colonies of D. pertusum in the area represent the first documented records for the Ligurian Sea. These data support the presence of a distinct eastern Ligurian cold-water coral province.

Particulate organic carbon dynamics in the Gulf of Lion shelf (NW Mediterranean) using a coupled hydrodynamic–biogeochemical model

Abstract. The Gulf of Lion shelf (GoL, NW Mediterranean) is one of the most productive areas in the Mediterranean Sea. A 3D coupled hydrodynamic–biogeochemical model is used to study the mechanisms that drive the particulate organic carbon (POC) dynamics over the shelf. A set of observations, including temporal series from a coastal station, remote sensing of surface chlorophyll a, and a glider deployment, is used to validate the distribution of physical and biogeochemical variables from the model. The model reproduces the time and spatial evolution of temperature, chlorophyll a, and nitrate concentrations well and shows a clear annual cycle of gross primary production and respiration. We estimate an annual net primary production of ∼ 200 × 104 t C yr−1 at the scale of the shelf. The primary production is marked by a coast-slope increase with maximal values in the eastern region. Our results show that the primary production is favoured by the inputs of nutrients imported from offshore waters, representing 3 and 15 times the inputs of the Rhône in terms of nitrate and phosphate. In addition, the empirical orthogonal function (EOF) decomposition highlights the role of solar radiation anomalies and continental winds that favour upwellings, and inputs of the Rhône River, in annual changes in the net primary production. Annual POC deposition (27 × 104 t C yr−1) represents 13 % of the net primary production. The delivery of terrestrial POC favours the deposition in front of the Rhône mouth, and the mean cyclonic circulation increases the deposition between 30 and 50 m depth from the Rhône prodelta to the west. Mechanisms responsible for POC export (24 × 104 t C yr−1) to the open sea are discussed. The export off the shelf in the western part, from the Cap de Creus to the Lacaze-Duthiers canyon, represents 37 % of the total POC export. Maximum values are obtained during shelf dense water cascading events and marine winds. Considering surface waters only, the POC is mainly exported in the eastern part of the shelf through shelf waters and Rhône inputs, which spread to the Northern Current during favourable continental wind conditions. The GoL shelf appears as an autotrophic ecosystem with a positive net ecosystem production and as a source of POC for the adjacent NW Mediterranean basin. The undergoing and future increase in temperature and stratification induced by climate change could impact the trophic status of the GoL shelf and the carbon export towards the deep basin. It is crucial to develop models to predict and assess these future evolutions.

Genetic diversity and structure of the narrow endemic Seseli farrenyi (Apiaceae): implications for translocation.

Seseli farrenyi (Apiaceae) is an extremely narrow endemic plant, which is considered as one of the species of most conservation concern in Catalonia (NW Mediterranean Basin). Given the accelerated fragmentation and reduction of population size (of over 90%), the environmental agency of Catalonia is currently preparing a recovery plan that includes reinforcements of the extant populations. The present study is aimed at providing the necessary knowledge to carry out genetically-informed translocations, by using microsatellites as genetic markers. Fourteen microsatellites have been specifically developed for S. farrenyi, of which nine have been used. Besides the extant natural populations, the three ex situ collections that are known to exist of this species have also been studied, as they would be the donor sources for translocation activities. Our main finding is that levels of genetic diversity in the natural populations of S. farrenyi are still high (He = 0.605), most likely as a result of a predominantly outcrossing mating system in combination with the limited time elapsed since the population decline. However, population fragmentation is showing the first genetic signs, as the values of genetic differentiation are relatively high, and two well-differentiated genetic lineages have been found even in such a narrow geographic range. These genetic results provide important information when designing conservation management measures.

River Deltas as hotspots of microplastic accumulation: The case study of the Ebro River (NW Mediterranean)

Microplastics (MPs) are considered pollutants that are ubiquitously distributed in aquatic environments. One of the key hotspot areas to understand fluxes of MPs entering into the oceans are transitional systems, between fresh and marine waters, where river estuaries in particular play an important role. In this study we analyzed MPs occurrence in the Ebro River Delta, Northeastern Iberian Peninsula, one of the largest wetland areas in the NW Mediterranean Basin. Microplastic profile, abundance, distribution, and characteristics were screened across different environmental matrices. MPs were collected in sandy beaches on the northern edge of the delta, in estuarine benthic sediments, and in surface waters of the Ebro River, with a mean abundance of 422 ± 119 MPs·kg−1 DW, 2052 ± 746 MPs·kg−1 DW and 3.5 ± 1.4 MPs·m−3, respectively. Fibers were found to be the largest class (70 ± 22%) of the three different environmental matrices investigated. We estimated that the Ebro surface water represents an input of 2.14 × 109 MPs·yr−1 to the Mediterranean Sea. The main contribution of this study is a new insight on the distribution of MPs across different environmental matrices in river estuaries, where estuarine benthic sediments were identified as a potential important sink for MPs.

Holocene paleoecological changes and agro-pastoral impact on the La Narce du Béage mire (Massif Central, France)

A paleoecological study (macrofossils, pollen, cryptogam spores, non-pollen palynomorphs) was performed to investigate environmental changes recorded on the peat deposits of the La Narce du Béage mire (Massif Central, France). We reconstructed the development of a limnogenous mire ecosystem during the Holocene, consequently to the infilling of a small Late Glacial lake. Successions from aquatic flora ( Isoëtes, Nitella opaca/ syncarpa, Botryococcus, Alisma plantago-aquatica, Potamogeton, Sparganium) to mire plant species ( Alnus glutinosa, Betula nana, Betula pubescens, Cyperaceae, Ericaceae, Sphagnum) underlined a gradual eutrophication and acidification during the lowering of the water table. We demonstrated a clear link between these local hydro-ecological changes and the early Holocene climatic warming. Also dealing with archeology, we provided key issues for the identification of human-induced environmental changes. Three phases of ecological disturbances with clearings of the mixed-oak forest and agro-pastoral activities were evidenced at 7700–7300, 6800–6420, and 5500–4250 cal. BP. Our results confirmed early Neolithic (Cardial influences), middle Neolithic (Chassean), and late Neolithic (Ferrières group) frequentations of the Béage Plateau, probably included in large-scale socio-cultural changes (SE France, NW Mediterranean Basin). Later, forest clearings (beech and fir), cultivation, and pastoralism were outlined since the Iron Age (after 2300 cal. BP, that is, 350 BC). Increasing human pressure was especially recorded during the last 1700 years, with rye ( Secale cereale) cultivation and extensive livestock grazing around and on the mire, which is nowadays a protected ‘Natura 2000’ area.

Geodynamical framework and hydrocarbon plays of a salt giant: the NW Mediterranean Basin

The NW Mediterranean Basin developed during the Oligocene–Miocene rifting of the Eastern Iberian–European magma-poor continental margin. The margin developed as a result of back-arc extension associated with the rollback of the retreating Calabrian–Tethys subduction zone. Reinterpretation of 2D regional seismic reflection data suggests that rifting took place by hyperextension of the Iberian–European lithosphere. This process led to the seawards arrangement of distinct crustal domains: namely, proximal, necking and distal. The late post-rift Messinian salinity crisis (MSC) gave rise to significant margin erosion and canyon incision, the lowstand sedimentary by-products of which were largely deposited prior to the Messinian evaporitic sequences. Mesozoic–Cenozoic and Messinian–Recent salt tectonics events have been recognized. A regional hydrocarbon play concept is proposed here for shelf–deep-water settings, including pre-salt, Messinian and post-salt plays.

Is long range transport of pollen in the NW Mediterranean basin influenced by Northern Hemisphere teleconnection patterns?

Climatic oscillations triggered by the atmospheric modes of the Northern Hemisphere teleconnection patterns have an important influence on the atmospheric circulation at synoptic scale in Western Mediterranean Basin. Simultaneously, this climate variability could affect a variety of ecological processes. This work provides a first assessment of the effect of North Atlantic Oscillation (NAO), Arctic Oscillation (AO) and Western Mediterranean Oscillation (WeMO) on the atmospheric long-range pollen transport episodes in the North-Eastern Iberian Peninsula for the period 1994–2011. Alnus, Ambrosia, Betula, Corylus and Fagus have been selected as allergenic pollen taxa with potential long-range transport associated to the Northern Hemisphere teleconnection patterns in the Western Mediterranean Basin. The results showed an increase of long range pollen transport episodes of: (1) Alnus, Corylus and Fagus from Western and Central Europe during the negative phase of annual NAO and AO; (2) Ambrosia, Betula and Fagus from Europe during the negative phase of winter WeMO; (3) Corylus and Fagus from Mediterranean area during the positive phase of the annual AO; and (4) Ambrosia from France and Northern Europe during the positive phase of winter WeMO. Conversely, the positive phase of annual NAO and AO are linked with the regional transport of Alnus, Betula and Corylus from Western Iberian Peninsula. The positive phase of annual WeMO was also positively correlated with regional transport of Corylus from this area.

Open sea hydrographic forcing of nutrient and phytoplankton dynamics in a Mediterranean coastal ecosystem

The dynamics of inorganic nutrients and phytoplankton was studied along two transects located in the coastal area of Barcelona (NW Mediterranean), from March 2002 to March 2006. Similar seasonal variability patterns were observed in the four annual cycles and in general, the nutrient concentrations were highest in winter and lowest in summer. Two phytoplankton peaks, composed mainly by diatoms and nanoflagellates, were generally detected during the year with the main peak during winter-early spring, linked to different fertilization mechanisms, and a secondary peak generally found in autumn, probably related both to the new availability of nutrients due to the disruption of the thermocline and to freshwater inputs. During the rest of the year, with a stratified water column and low nutrient concentrations, phytoplankton remained at a low abundance and comprised mainly small dinoflagellates, although there was smaller scale variability conditioned by rainfall events and subsequent freshwater discharges. Despite the similarity of the seasonal patterns, there were interannual changes in origin of new nutrient inputs into the coastal zone and in the taxonomic composition of the winter-early spring phytoplankton maxima. The main source of nutrients for the winter-early spring maxima of 2003 and 2004 was river runoff, while fertilization events in the two following winters were mainly due to the intrusion, onto the Barcelona shelf, of intermediate waters in 2005, and of surface offshore waters, which also carried a different phytoplankton community, in 2006. These changes were linked to unusually cold and dry weather in the winters of 2005 and 2006, which resulted in strong vertical mixing and deep water formation events in the NW Mediterranean basin. The overall amount of nutrients provided to the coastal zone by offshore water fertilization was higher (2005) or equal (2006) than that provided by freshwater inputs in 2003 and 2004. Our findings highlight the importance of identifying the different sources of nutrients in understanding the dynamics of phytoplankton and for devising management strategies of the coastal environment.

Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin

MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean Basin (WMB). The measurements were performed at a semidesertic area (Monegros), at a coastal Mediterranean shrubland area (Garraf), at a typical Mediterranean holm oak forest area (Prades) and at a wet temperate beech forest (Montseny) during spring (April 2010) under optimal plant physiological conditions in driest-warmest sites and during summer (July 2010) with drought and heat stresses in the driest–warmest sites and optimal conditions in the wettest–coolest site. The objective of this campaign was to study the differences in gas, water and energy exchange occurring at different vegetation coverages and biomasses. Particular attention was devoted to quantitatively understand the exchange of biogenic volatile organic compounds (BVOCs) because of their biological and environmental effects in the WMB. A wide range of instruments (GC–MS, PTR-MS, meteorological sensors, O3 monitors,…) and vertical platforms such as masts, tethered balloons and aircraft were used to characterize the gas, water and energy exchange at increasing footprint areas by measuring vertical profiles. In this paper we provide an overview of the MONTES campaign: the objectives, the characterization of the biomass and gas, water and energy exchange in the 4 sites-areas using satellite data, the estimation of isoprene and monoterpene emissions using MEGAN model, the measurements performed and the first results. The isoprene and monoterpene emission rates estimated with MEGAN and emission factors measured at the foliar level for the dominant species ranged from about 0 to 0.2 mg m−2 h−1 in April. The warmer temperature in July resulted in higher model estimates from about 0 to ca. 1.6 mg m−2 h−1 for isoprene and ca. 4.5 mg m−2 h−1 for monoterpenes, depending on the site vegetation and footprint area considered. There were clear daily and seasonal patterns with higher emission rates and mixing ratios at midday and summer relative to early morning and early spring. There was a significant trend in CO2 fixation (from 1 to 10 mg C m−2 d−1), transpiration (from 1–5 kg C m−2 d−1), and sensible and latent heat from the warmest–driest to the coolest–wettest site. The results showed the strong land-cover-specific influence on emissions of BVOCs, gas, energy and water exchange, and therefore demonstrate the potential for feed-back to atmospheric chemistry and climate.

Interaction of dense shelf water cascading and open‐sea convection in the northwestern Mediterranean during winter 2012

AbstractThe 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.

MBAS (Methylene Blue Active Substances) and LAS (Linear Alkylbenzene Sulphonates) in Mediterranean coastal aerosols: Sources and transport processes

Abstract Methylene Blue Active Substances (MBAS) and Linear Alkylbenzene Sulphonates (LAS) concentrations, together with organic carbon and ions were measured in atmospheric coastal aerosols in the NW Mediterranean Basin. Previous studies have suggested that the presence of surfactants in coastal aerosols may result in vegetation damage without specifically detecting or quantifying these surfactants. Coastal aerosols were collected at a remote site (Porquerolles Island-Var, France) and at a more anthropised site (San Rossore National Park-Tuscany, Italy). The chemical data were interpreted according to a comprehensive local meteorological analysis aiming to decipher the airborne source and transport processes of these classes of compounds. The LAS concentration (anthropogenic surfactants) was measured in the samples using LC-MS/MS, a specific analytical method. The values were compared with the MBAS concentration, determined by a non-specific analytical method. At Porquerolles, the MBAS concentration (103 ± 93 ng m −3 ) in the summer samples was significantly higher than in the winter samples. In contrast, LAS concentrations were rarely greater than in the blank filters. At San Rossore, the mean annual MBAS concentration (887 ± 473 ng m −3 in PM10) contributed about 10% to the total atmospheric particulate organic matter. LAS mean concentration in these same aerosol samples was 11.5 ± 10.5 ng m −3 . A similar MBAS (529 ± 454 ng m −3 ) – LAS (7.1 ± 4.1 ng m −3 LAS) ratio of ∼75 was measured in the fine (PM2.5) aerosol fraction. No linear correlation was found between MBAS and LAS concentrations. At San Rossore site the variation of LAS concentrations was studied on a daily basis over a year. The LAS concentrations in the coarse fraction (PM10–2.5) were higher during strong sea storm conditions, characterized by strong air flow coming from the sea sector. These events, occurring with more intensity in winter, promoted the formation of primary marine aerosols containing LAS from the sea surface microlayer. In contrast to LAS, MBAS concentrations in the coarse fraction peaked in summer. Therefore, different sources are suggested for the two classes of compounds. In summer, increased MBAS concentration could be an indicator of phytoplanktonic blows enriching the sea surface microlayer with biogenic surfactants. In winter, some spikes in MBAS concentrations in the coarse fraction could be related to LAS concentrations and sea storm events. Moreover, in the fine fraction MBAS have a large concentration maxima in winter, corresponding to air masses coming from polluted continental areas. It is concluded that MBAS concentration in the fine or the coarse fraction is not an appropriate surrogate measurement of LAS concentration in aerosols because of the significant contribution from other sources to the MBAS concentration.

Transient erosion in the Valencia Trough turbidite systems, NW Mediterranean Basin

Submarine canyons can efficiently drain sediments from continental margins just as river systems do in subaerial catchments. Like in river systems, submarine canyons are often arranged as complex drainage networks that evolve from patterns of erosion and deposition. In the present paper we use a morphometric analysis of submarine canyon-channel long-profiles to study the recent sedimentary history of the Valencia Trough turbidite system (VTTS) in the NW Mediterranean Sea. The VTTS is unique in that it drains sediment from margins with contrasting morphologies through a single “trunk” conduit, the Valencia Channel. The Valencia Channel has been active since the late Miocene, evolving in response to Plio-Quaternary episodes of erosion and deposition. The integrated analysis of long-profiles obtained from high-resolution bathymetric data across the entire turbidite system shows evidence for transient canyon incision in the form of knickpoints and hanging tributaries. Multiple factors appear to have triggered these periods of incision. These include a large debris flow at 11,500yrBP that disrupted the upper reaches of the VTTS and glacio-eustatic lowstands that forced shifting of sediment input to the VTTS. Based on these inferences, long-term time-averaged incision rates for the Valencia Channel have been estimated. The evidence we present strongly suggests that Foix Canyon has played a key role in the drainage dynamics of the VTTS in the past.This study builds conceptually on a recent modeling study that provides a morphodynamic explanation for the long-term evolution of submarine canyon thalweg profiles. The procedure and results from this work are of potential application to other submarine sediment drainage systems, past and present, including those containing mid-ocean type valleys like the Valencia Channel.

Crustal structure of a young margin pair: New results across the Liguro–Provencal Basin from wide-angle seismic tomography

Tomographic inversion of two wide-angle seismic profiles acquired during the Sardinia cruise (2006) on the conjugate Gulf of Lions–West Sardinia margins pair offers insight into the deep structure of this young basin. It is the first combined conjugate margins study in this area based on deep seismic data. Modelling of the two conjugate profiles reveals that the conjugate margins are symmetric in term of crustal velocity structure, with a partitioning in three similar regions: (1) a zone of low crustal vertical velocity gradients and a crustal thickness of 18 to 10 km, interpreted to be thinned continental crust, (2) a transitional zone characterised by high lower crustal velocities, non-typical of continental or normal oceanic crust, and (3) a 4- to 5-km-thick crust showing vertical velocity gradients and relative velocity ranges typical of oceanic crust. This latter region is interpreted to be a thin oceanic crust resulting from a tectonic heritage and the possible influence of a cool slab back-arc basin. Although the three regions are found on both sides of the margin, they are asymmetric in terms of the width of these domains, wide and smooth along the Gulf of Lions margin, and narrow and abrupt along its conjugate Sardinia side. The width of Region 2 is larger on the Gulf of Lions side (~ 90 km) than on the Sardinia side (~ 40 km). Crustal thickness in Region 3 is about 1 km thinner on the Sardinia side than on its conjugate. In Region 1 the crustal thickness is lower on the Sardinia side at a given distance from the shelf break. The differences in width of Region 2 and in crustal thickness might be due to the origin as a back-arc basin of the NW-Mediterranean basin, with the final breakup located closer to the Western Sardinia margin, also probably linked to the complex tectonic history of the region. Our results do not support a simple shear mechanism of the opening of the basin along a lithospheric detachment fault.

Morphogenetic mesoscale analysis of the northeastern Iberian margin, NW Mediterranean Basin

The compilation of several multibeam data sets unveils for the first time the seafloor of almost the entire northeastern Iberian margin, in the northwestern Mediterranean Basin. This is achieved thanks to an international effort involving mainly Spanish and French research institutions. Submarine canyons, turbiditic channels, landslides and a mid-oceanic valley are the main sedimentary features observed. The size and shape of these features vary throughout the margin. However, the morphometric analysis performed leads to the subdivision of the margin in three main segments: North Catalan Margin (NCM), South Catalan Margin (SCM) and Ebro Margin (EM). We address a non-frequently used scale to tackle the question of which are the main mechanisms controlling the morphological variability between these margins. This is the mesoscale (from one to several hundred kilometres), which allows a comprehensive, holistic and detailed analysis of the seascaping mechanisms shaping the continental margin of northeastern Iberia. Preliminary results suggest that factors controlling the seascape involve a combination of tectonics, long-term fluvial sediment flux to the margin, sediment grain size, basin depth and slope gradient. Modelling of these morphogenetic relationships will contribute to a better knowledge of the seascape development in mid-latitude siliciclastic margins.

Effects of a nutrient pulse supply on nutrient status of the Mediterranean trees Quercus ilex subsp. ballota and Pinus halepensis on different soils and under different competitive pressure

Nutrient availability is a key factor in Mediterranean ecosystems that affects the primary productivity and the community structure. The great variability of its natural availability is now increasing due to frequent fires, pollution events and changes in rainfall regime associated to climate change. Quercus ilex ssp. ballota and Pinus halepensis are the most abundant tree species in the NW Mediterranean basin. They frequently compete in the early and middle successional stages. We investigated the effects of N and P pulse supplies on nutrient uptake capacity in these two species in an after-fire field area and in nursery conditions on different soil types and competing conditions. In the field, N fertilisation had weak effects on nutrient concentration and mineralomass likely as a consequence of this nutrient not being limiting in this field site whereas P fertilisation increased the P mineralomass and the Mg, S, Fe, K and Ca concentrations and mineralomass in the different biomass fractions of both species 1 and 3 years after fertilisation application. In the nursery experiments, P fertilisation increased the mineralomass and concentrations of P, Mg, S, Fe, K and Ca in all biomass fractions including the roots in both species and in different soils and competition conditions. The increment of nutrient mineralomass was due to both the increase of growth and of nutrient concentrations. Both species were able to absorb significant amounts of the P applied by fertilisation (between 5 and 20%) in short time (18 months). Competing vegetation decreased the positive effects of P fertilisation, and in many cases the negative effect of competing vegetation on nutrient mineralomass was stronger when P availability was increased by fertilisation. Q. ilex subsp ballota showed a greater competitive ability for P than the more pioneer species Pinus halepensis in the field but not in the nursery conditions. Pinus halepensis had greater nutrient mineralomass in calcareous than in siliceous soils. Q. ilex subsp. ballota had a higher root biomass allocation and root nutrient allocation than P. halepensis, but both species showed a high capacity to increase their nutrient uptake when its availability increased by fertilisation, thus assuring a great nutrient reserve for future growth periods and contributing to retain nutrients in the ecosystem.

Carbon isotope composition of fossil charcoal reveals aridity changes in the NW Mediterranean Basin

AbstractAlthough several proxies for the inference of precipitation have been proposed, evidence of changes in aridity during the Holocene is scarce, and most is only qualitative. Moreover, precipitation regimes show relatively poor spatial correlations and can exhibit contrasting responses to global climate trends in different areas. Thus, there is a need to concentrate efforts at the local scale in order to increase the spatial resolution of palaeoclimate records, especially regarding water availability in semiarid zones. We propose the analysis of carbon isotope composition (δ13C) in fossil charcoal (routinely recovered from archaeological sites) to quantify changes in water availability in the past. We applied this approach to reconstruct variations in aridity during the last four millennia in the Ebro Depression (NE Iberian Peninsula). First, we studied the effect of carbonization over a range of temperatures (300–500°C) on the δ13C of Aleppo pine (Pinus halepensis Mill.) wood cores, collected from nine locations in NE Iberian Peninsula with distinct water availability. Despite significant changes in δ13C caused by carbonization, the original climatic signal of wood δ13C was well preserved. Moreover, δ13C shifts induced by this process were successfully corrected by accounting for variation in charcoal carbon concentration (%C). After removing the effect of carbonization, we estimated annual precipitation (P) and the ratio between annual precipitation and evapotranspiration (P/E) from the δ13C of fossil charcoal. In general, estimated water availability in the past was higher than present values, indicating that latter‐day (semiarid) conditions are mostly due to recent climate changes. The good agreement between our findings and other evidence indicates that the analysis of δ13C in charcoal may be useful to expand current palaeoclimate records as it provides a complementary (and quantitative) source of information to assess climate dynamics.

Stratral architectures of late Quaternary regressive–transgressive cycles in the Roussillon Shelf (SW Gulf of Lions, France)

A seismic and sequence stratigraphy scheme of the southwestern area of the Gulf of Lions Shelf (NW Mediterranean Basin) is presented, through the analysis of high-resolution seismic profiles obtained with a Minisparker system and calibrated with published seismic and core data of the adjacent Languedoc area. The observed stratigraphic architecture records the repetition of four regressive–transgressive cycles, which constitute high-frequency depositional sequences (DSs). Regressive intervals dominate the generation of shelf sedimentary architecture. Within regressive intervals, the identification of progressively shallower clinoforms, from proximal to distal in a downdip direction, constitutes a strong indicator of the occurrence of forced regressions. This stratigraphic pattern documents the preservation of potential sand-prone reservoirs encased within widespread regressive wedges and directly connected with organic matter rich muds, as distally there is no sharp basal contact between the two. The unusual preservation of pre-Last Glacial Maximum transgressive deposits is attributed to the combined influence of previous shelf topography and dominant wave regime. The most significant transgressions were recorded by shallow-water deposits in distal, middle and proximal locations. Distal and proximal deposits develop over relatively steep surfaces, which caused slower transgressions and favoured the generation of wave-dominated coastal deposits. In contrast, middle deposits show moderate development over a smooth shelf profile as a consequence of rapid shoreline translation. The analysis of spatial changes of regressive–transgressive cycles provided important information about the nature of shelf processes and about the relative significance of regressive versus transgressive intervals within each individual DS, whose development was led by recent, high-frequency sea-level cycles. Dominance of 120 ka cycles would imply that transgressive deposits represent a partial record of glacial–interglacial transgressions. Dominance of 20 ka cycles is not favoured by the fact that the preservation of Quaternary deposits is apparently limited on the shelf.

Phytodetritus at the sediment-water interface, NW Mediterranean Basin: spatial repartition, living cells signatures, meiofaunal relationships

was low (< 0.2 µg Chl a l-1), with the lowest standing stocks on the eastern part of the Balearic Basin. Two sedimentary entities were identified: 1) the west coast where pigment concentrations were higher, with an average of 0.38 µg Chl a g -1 dry weight and 4.60 Phaeo a g-1 dw on the first half cm of sediments; and 2) the eastern part of the North Balearic basin where pigment concentrations were significantly lower (0.15 µg Chl a g -1 dw). A north to south gradient was observed, with higher pigment amounts on the Rhodanian slope. Differences were found in the different parts of the studied canyons, with a slight increase in the Axis sites. The vertical pigment repartition was a gradual decrease in the Interfluve sites, whereas concentrations decreased sharply below the first cm in the Axis sites, attesting differences in sedimentation, grazing or bioturbation within the different canyon parts. The north to south gradient in the phytoplankton Chl a/Chl b ratio and sedimented phytodetritus attest geographical differences within phytoplankton assemblages (i.e. diatoms are absent in the south). The epifluorescence tests from the interface revealed the presence of living microphytes at the northern sites, associated with aggregates and faeces. No consistent fluff was evidenced anywhere. The revival tests also agree with a north to south trend. The Meiofaunal density was positively related to the quality of the sedimented layer. A PCA, within the major parameters and factors, illustrates these relationships. All results allow two distinct geographical sectors to be discriminated around the frontal zone: the NW and E sides of the NW Mediterranean Basin, following in particular their contrasted hydrodynamics. The results indicated the relationships within phytoplankton input, underlying phytodetritic layer and meiofauna. They confirm the well-documented statement that demonstrates the deep-sea floor chloropigment concentration to be a good proxy for the overlying primary productivity, but also that some pigment ratios representative of plankton assemblages are preserved on surficial deep sediments, even after sedimentation and grazing.

The eastern end of the Pyrenees: Seismic features at the transition to the NW Mediterranean

The deep crustal features at the transition from the Pyrenean range to the NW Mediterranean basin have been investigated by onshore/offshore recording of LIgurian SArdinian (LISA) seismic profiles. The predominance in this area of the Neogene extensional tectonics over the Paleogene compressional one is revealed from the present‐day deep structure sampled by the new wide‐angle data. The existence of a crustal root beneath the Pyrenean Axial Zone and the outstanding differences in Moho depths between the Iberian and European domains, well established from previous seismic studies on central and western Pyrenees, are not observed anymore at the easternmost part of the range. This area is marked by a continued crustal thinning seawards (the Moho rises about 10 km along distances of 60 km) that affects already the mainland. Further evidences on lateral variations and topography of the crust‐mantle boundary are indicative of the extent of the different tectonic episodes.

Xenobiotic metabolising enzymes and antioxidant defences in deep-sea fish:relationship with contaminant body burden

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 192:259-266 (2000) - doi:10.3354/meps192259 Xenobiotic metabolising enzymes and antioxidant defences in deep-sea fish: relationship with contaminant body burden Cinta Porte*, Estefania Escartín, Luz M. García, Montserrat Solé, Joan Albaigés Department of Environmental Chemistry, IIQAB-CSIC, Jordi Girona 18, 08034 Barcelona, Spain *E-mail: cpvqam@cid.csic.es ABSTRACT: Xenobiotic metabolising enzymes, namely the cytochrome P450 monooxygenase system and glutathione S-transferase, as well as antioxidant enzymes were determined in the liver of 3 deep-sea fish species (Lepidion lepidion, Bathypterois mediterraneus and Coryphaenoides guentheri). These organisms were collected from 3 stations along the NW Mediterranean, at depths ranging from 1500 to 1800 m. The enzymatic activities detected in deep-sea fish indicated the ability of these organisms to cope with pollutants and oxidative stress. Differences among the studied species may be related to habitat and diet, viz. the highest monooxygenase and antioxidant enzyme activities were observed in L. lepidion, a typical middle slope species, whereas the lowest activities were recorded for B. mediterraneus, an organism adapted to live at greater depths. Tissue concentration of persistent organochlorinated compounds, like polychlorinated biphenyls, DDTs and hexachlorobenzene, were in the lower range of those reported for coastal fish, and significant differences among sampling stations were not observed. Overall, the obtained results contribute to the knowledge of the NW Mediterranean deep-sea basin and reflect the chronic contamination of the area in terms of organochlorinated compounds, rather than the influence of coastal discharges. KEY WORDS: Deep-sea fish · Cytochrome P450 · EROD · GST · Antioxidant enzymes · PCBs · PAHs in bile Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 192. Publication date: January 31, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.