Particulate biogenic barium tracer of mesopelagic carbon remineralization in the Mediterranean Sea (PEACETIME project)

Abstract. We report on the sub-basin variability in particulate organic carbon (POC) remineralization in the western and central Mediterranean Sea in late spring during the PEACETIME (ProcEss studies at the Air–sEa Interface after dust deposition in the MEditerranean sea) cruise. POC remineralization rates were estimated using the excess biogenic particulate barium (Baxs) inventories in the mesopelagic layers (100–1000 m depth) and compared with prokaryotic heterotrophic production (PHP). Baxs-based mesopelagic remineralization rates (MRs) ranged from 25±2 to 306±70 mgCm-2d-1. MRs were larger in the Algero-Provençal (ALG) Basin than in the Tyrrhenian (TYR) and Ionian (ION) basins. Our Baxs inventories and integrated PHP data also indicated that significant mesopelagic remineralization occurred down to 1000 m depth in the ALG Basin in contrast to the ION and TYR basins, where remineralization was mainly located above 500 m depth. We propose that the higher and deeper MRs in the ALG Basin were sustained by an additional particle export event driven by deep convection. The TYR Basin (in contrast to the ALG and ION basins) presented the impact of a previous dust event, as reflected by our particulate Al water column concentrations. The ION and TYR basins showed small-scale heterogeneity in remineralization processes, reflected by our Baxs inventories and integrated PHP data at the Tyrr long-duration station. This heterogeneity was linked to the mosaic of blooming and non-blooming patches reported in this area during the cruise. In contrast to the western Mediterranean Sea (ALG Basin), the central Mediterranean Sea (ION and TYR basins) showed lower remineralization rates restricted to the upper mesopelagic layer during the late spring PEACETIME cruise.

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Summertime surface PM<sub>1</sub> aerosol composition and size by source region at the Lampedusa island in the central Mediterranean Sea

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11123-2019 ◽

2019 ◽

Vol 19 (17) ◽

pp. 11123-11142 ◽

Cited By ~ 3

Author(s):

Marc D. Mallet ◽

Barbara D'Anna ◽

Aurélie Même ◽

Maria Chiara Bove ◽

Federico Cassola ◽

...

Keyword(s):

Mediterranean Sea ◽

Ammonium Sulfate ◽

Organic Aerosol ◽

Western Mediterranean ◽

Central Mediterranean ◽

Aerosol Composition ◽

Air Masses ◽

Westerly Winds ◽

Central Mediterranean Sea ◽

The Mediterranean

Abstract. Measurements of aerosol composition and size distributions were taken during the summer of 2013 at the remote island of Lampedusa in the southern central Mediterranean Sea. These measurements were part of the ChArMEx/ADRIMED (Chemistry and Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate) framework and took place during Special Observation Period 1a (SOP-1a) from 11 June to 5 July 2013. From compact time-of-flight aerosol mass spectrometer (cToF-AMS) measurements in the size range below 1 µm in aerodynamic diameter (PM1), particles were predominately comprised of ammonium and sulfate. On average, ammonium sulfate contributed 63 % to the non-refractory PM1 mass, followed by organics (33 %). The organic aerosol was generally very highly oxidized (f44 values were typically between 0.25 and 0.26). The contribution of ammonium sulfate was generally higher than organic aerosol in comparison to measurements taken in the western Mediterranean but is consistent with studies undertaken in the eastern basin. Source apportionment of organics using a statistical (positive matrix factorization) model revealed four factors: a hydrocarbon-like organic aerosol (HOA), a methanesulfonic-acid-related oxygenated organic aerosol (MSA-OOA), a more oxidized oxygenated organic aerosol (MO-OOA) and a less oxidized oxygenated organic aerosol (LO-OOA). The MO-OOA was the dominant factor for most of the campaign (53 % of the PM1 OA mass). It was well correlated with SO42-, highly oxidized and generally more dominant during easterly air masses originating from the eastern Mediterranean and central Europe. The LO-OOA factor had a very similar composition to the MO-OOA factor but was more prevalent during westerly winds, with air masses originating from the Atlantic Ocean, the western Mediterranean and at high altitudes over France and Spain from mistral winds. The MSA-OOA factor contributed an average 12 % to the PM1 OA and was more dominant during the mistral winds. The HOA, representing observed primary organic aerosol, only contributed 8 % of the average PM1 OA during the campaign. Even though Lampedusa is one of the most remote sites in the Mediterranean, PM1 concentrations (10 ± 5 µg m−3) were comparable to those observed in coastal cities and sites closer to continental Europe. Cleaner conditions corresponded to higher wind speeds. Nucleation and growth of new aerosol particles was observed during periods of north-westerly winds. From a climatology analysis from 1999 to 2012, these periods were much more prevalent during the measurement campaign than during the preceding 13 years. These results support previous findings that highlight the importance of different large-scale synoptic conditions in determining the regional and local aerosol composition and oxidation and also suggest that a non-polluted surface atmosphere over the Mediterranean is rare.

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Summertime surface PM<sub>1</sub> aerosol composition and size by source region at the Lampedusa island in the central Mediterranean Sea

10.5194/acp-2019-192 ◽

2019 ◽

Author(s):

Marc D. Mallet ◽

Barbara D'Anna ◽

Aurélie Même ◽

Maria Chiara Bove ◽

Federico Cassola ◽

...

Keyword(s):

Mediterranean Sea ◽

Ammonium Sulphate ◽

Organic Aerosol ◽

Western Mediterranean ◽

Dominant Factor ◽

Central Mediterranean ◽

Aerosol Composition ◽

Air Masses ◽

Central Mediterranean Sea ◽

The Mediterranean

Abstract. Measurements of aerosol composition and size distributions were taken during the summer of 2013 at the remote island of Lampedusa in the southern central Mediterranean Sea. These measurements were part of the ChArMEx/ADRIMED (Chemistry and Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate) framework and took place during the Special Observation Period 1a (SOP-1a) from 11 June until 5 July 2013. From compact time-of-flight aerosol mass spectrometer (cToF-AMS) measurements in the size range below 1 μm in aerodynamic diameter (PM1), particles were predominately comprised of ammonium and sulphate. On average, ammonium sulphate contributed 63 % to the non-refractory PM1 mass, followed by organics (33 %). The organic aerosol was generally very highly oxidised (f44 values were typically between 0.25 and 0.26). The contribution of ammonium sulphate was generally higher than organic aerosol in comparison to measurements taken in the western Mediterranean but is consistent with studies undertaken in the eastern basin. Source apportionment of organics using a statistical (positive matrix factorisation) model revealed four factors; a hydrocarbon-like organic aerosol (HOA), a methanesulfonic acid related oxygenated organic aerosol (MSA-OOA), a more oxidised oxygenated organic aerosol (MO-OOA) and a less oxidised oxygenated organic aerosol we label (LO-OOA). The MO-OOA was the dominant factor for most of the campaign (53 % of the PM1 OA mass). It was well correlated with SO42−, highly oxidised, and generally more dominant during easterly air masses originating from the eastern Mediterranean and central Europe. The LO-OOA factor had a very similar composition to the MO-OOA factor, but was more prevalent during westerly winds with air masses originating from the Atlantic Ocean, the western Mediterranean, and in high altitudes over France and Spain from mistral winds. The MSA-OOA factor contributed an average 12 % to the PM1 OA and was more dominant during the mistral winds. The HOA, representing observed primary organic aerosol only contributed 8 % of the average PM1 OA during the campaign. Even though Lampedusa is one of the most remote sites in the Mediterranean, PM1 concentrations (10 ± 5 μg m−3) were comparable to those observed in coastal cities and sites closer to continental Europe. Cleaner conditions corresponded to higher wind speeds. Nucleation and growth of new aerosol particles was observed during periods of northwesterly winds. From a climatology analysis from 1999 until 2012, these periods were much more prevalent during the measurement campaign than during the preceding 13 years. These results support previous findings that highlight the importance of different large-scale synoptic conditions in determining the regional and local aerosol composition and oxidation and also suggest that a non-polluted surface atmosphere over the Mediterranean is rare.

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The impact of marine litter from fish aggregation devices on vulnerable marine benthic habitats of the central Mediterranean Sea

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2020.110928 ◽

2020 ◽

Vol 152 ◽

pp. 110928 ◽

Cited By ~ 3

Author(s):

Pierpaolo Consoli ◽

Mauro Sinopoli ◽

Alan Deidun ◽

Simonepietro Canese ◽

Claudio Berti ◽

...

Keyword(s):

Mediterranean Sea ◽

Central Mediterranean ◽

Benthic Habitats ◽

Marine Litter ◽

Central Mediterranean Sea ◽

Fish Aggregation ◽

The Impact

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Trade and stowaways: molecular evidence for human-mediated translocation of eastern skinks into the western Mediterranean

Amphibia-Reptilia ◽

10.1163/15685381-20191249 ◽

2020 ◽

Vol 41 (1) ◽

pp. 49-62

Author(s):

Josep Francesc Bisbal-Chinesta ◽

Karin Tamar ◽

Ángel Gálvez ◽

Luís Albero ◽

Pablo Vicent-Castelló ◽

...

Keyword(s):

Iberian Peninsula ◽

Mediterranean Sea ◽

Western Mediterranean ◽

Molecular Evidence ◽

Long Distance ◽

Human Movements ◽

Allochthonous Species ◽

The Mediterranean ◽

Chalcides Ocellatus ◽

The Impact

Abstract Human movements in the regions surrounding the Mediterranean Sea have caused a great impact in the composition of terrestrial fauna due to the introductions of several allochthonous species, intentionally or not. Reptiles are one of the groups where this anthropic impact is most evident, owing to the extensive intra-Mediterranean dispersals of recent chronologies. Chalcides ocellatus is a widespread skink with a natural distribution that covers almost the entire Mediterranean Basin. Two hypotheses have been proposed to explain its origin: natural dispersions and human translocations. Previous molecular data suggest the occurrence of a recent dispersal phenomenon across the Mediterranean Sea. In this study we present the first record of this species in the Iberian Peninsula, in Serra del Molar (South-east Spain). We combined molecular analyses and archaeological records to study the origin of this population. The molecular results indicate that the population is phylogenetically closely related to specimens from north-eastern Egypt and southern Red Sea. We suggest that the species arrived at the Iberian Peninsula most likely through human-mediated dispersal by using the trade routes. Between the Iron to Middle Ages, even now, the region surrounding Serra del Molar has been the destination of human groups and commercial goods of Egyptian origins, in which Chalcides ocellatus could have arrived as stowaways. The regional geomorphological evolution would have restricted its expansion out of Serra del Molar. These findings provide new data about the impact of human movements on faunal introductions and present new information relating to mechanisms of long-distance translocations.

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The impact of fisheries on vulnerable habitats: the case of trawling on circa-littoral grounds in the Strait of Sicily (central Mediterranean Sea)

Marine Biology Research ◽

10.1080/17451000.2017.1348010 ◽

2017 ◽

Vol 13 (10) ◽

pp. 1084-1094 ◽

Cited By ~ 2

Author(s):

Pierpaolo Consoli ◽

Valentina Esposito ◽

Manuela Falautano ◽

Pietro Battaglia ◽

Luca Castriota ◽

...

Keyword(s):

Mediterranean Sea ◽

Central Mediterranean ◽

Strait Of Sicily ◽

Central Mediterranean Sea ◽

Vulnerable Habitats ◽

The Impact

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Interannual variability of the Mediterranean trophic regimes from ocean color satellites

Biogeosciences Discussions ◽

10.5194/bgd-12-14941-2015 ◽

2015 ◽

Vol 12 (17) ◽

pp. 14941-14980 ◽

Cited By ~ 4

Author(s):

N. Mayot ◽

F. D'Ortenzio ◽

M. Ribera d'Alcalà ◽

H. Lavigne ◽

H. Claustre

Keyword(s):

Spatial Distribution ◽

Mediterranean Sea ◽

Interannual Variability ◽

Deep Convection ◽

Regional Scale ◽

Ocean Color ◽

Run Off ◽

The Mediterranean ◽

The One ◽

The Impact

Abstract. D'Ortenzio and Ribera d'Alcalà (2009, DR09 hereafter) divided the Mediterranean Sea into "bioregions" based on the climatological seasonality (phenology) of phytoplankton. Here we investigate the interannual variability of this bioregionalization. Using 16 years of available ocean color observations (i.e. SeaWiFS and MODIS), we analyzed the spatial distribution of the DR09 trophic regimes on an annual basis. Additionally, we identified new trophic regimes, with seasonal cycles of phytoplankton biomass different from the DR09 climatological description and named "Anomalous". Overall, the classification of the Mediterranean phytoplankton phenology proposed by DR09 (i.e. "No Bloom", "Intermittently", "Bloom" and "Coastal"), is confirmed to be representative of most of the Mediterranean phytoplankton phenologies. The mean spatial distribution of these trophic regimes (i.e. bioregions) over the 16 years studied is also similar to the one proposed by DR09. But at regional scale some annual differences, in their spatial distribution and in the emergence of "Anomalous" trophic regimes, were observed compared to the DR09 description. These dissimilarities with the DR09 study were related to interannual variability in the sub-basin forcing: winter deep convection events, frontal instabilities, inflow of Atlantic or Black Sea Waters and river run-off. The large assortment of phytoplankton phenologies identified in the Mediterranean Sea is thus verified at interannual level, confirming the "sentinel" role of this basin to detect the impact of climate changes on the pelagic environment.

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Remarks on Echinodermata from the South Central Mediterranean Sea based upon collections made during the MARCOS cruise (10 to 20th April, 2007)

Mediterranean Marine Science ◽

10.12681/mms.109 ◽

2009 ◽

Vol 10 (2) ◽

pp. 63 ◽

Cited By ~ 5

Author(s):

C. MIFSUD ◽

M. TAVIANI ◽

S. STOHR

Keyword(s):

Mediterranean Sea ◽

The South ◽

Central Mediterranean ◽

Management Zone ◽

Maltese Islands ◽

South Central ◽

Central Mediterranean Sea ◽

The Mediterranean ◽

First Time ◽

The Mediterranean Basin

The MARCOS cruise, which took place in the South Central Mediterranean Sea on board the RV ‘Urania’, resulted in the collection of 27 species of Echinodermata from shallow to bathyal depths, many from around Malta (the Fisheries Management Zone). The fauna is represented by common to rare taxa already reported from the Mediterranean with the exception of the amphi-Atlantic ophiuroid Ophiotreta valenciennesi rufescens (Koehler, 1896), recorded from the Mediterranean Basin for the first time. Odontaster mediterraneus (von Marenzeller, 1893) and Luidia sarsi Lutken, 1858 are also first records for the Maltese Islands.

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Oxygen budget of the north-western Mediterranean deep- convection region

Biogeosciences ◽

10.5194/bg-18-937-2021 ◽

2021 ◽

Vol 18 (3) ◽

pp. 937-960

Author(s):

Caroline Ulses ◽

Claude Estournel ◽

Marine Fourrier ◽

Laurent Coppola ◽

Fayçal Kessouri ◽

...

Keyword(s):

Dissolved Oxygen ◽

Mediterranean Sea ◽

Atmospheric Oxygen ◽

Deep Convection ◽

Western Mediterranean ◽

Biogeochemical Model ◽

The North ◽

Oxygen Budget ◽

The Mediterranean ◽

North Western

Abstract. The north-western Mediterranean deep convection plays a crucial role in the general circulation and biogeochemical cycles of the Mediterranean Sea. The DEWEX (DEnse Water EXperiment) project aimed to better understand this role through an intensive observation platform combined with a modelling framework. We developed a three-dimensional coupled physical and biogeochemical model to estimate the cycling and budget of dissolved oxygen in the entire north-western Mediterranean deep-convection area over the period September 2012 to September 2013. After showing that the simulated dissolved oxygen concentrations are in a good agreement with the in situ data collected from research cruises and Argo floats, we analyse the seasonal cycle of the air–sea oxygen exchanges, as well as physical and biogeochemical oxygen fluxes, and we estimate an annual oxygen budget. Our study indicates that the annual air-to-sea fluxes in the deep-convection area amounted to 20 molm-2yr-1. A total of 88 % of the annual uptake of atmospheric oxygen, i.e. 18 mol m−2, occurred during the intense vertical mixing period. The model shows that an amount of 27 mol m−2 of oxygen, injected at the sea surface and produced through photosynthesis, was transferred under the euphotic layer, mainly during deep convection. An amount of 20 mol m−2 of oxygen was then gradually exported in the aphotic layers to the south and west of the western basin, notably, through the spreading of dense waters recently formed. The decline in the deep-convection intensity in this region predicted by the end of the century in recent projections may have important consequences on the overall uptake of atmospheric oxygen in the Mediterranean Sea and on the oxygen exchanges with the Atlantic Ocean, which appear necessary to better quantify in the context of the expansion of low-oxygen zones.

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Subsurface iron accumulation and rapid aluminum removal in the Mediterranean following African dust deposition

Biogeosciences ◽

10.5194/bg-18-6435-2021 ◽

2021 ◽

Vol 18 (24) ◽

pp. 6435-6453

Author(s):

Matthieu Bressac ◽

Thibaut Wagener ◽

Nathalie Leblond ◽

Antonio Tovar-Sánchez ◽

Céline Ridame ◽

...

Keyword(s):

Mediterranean Sea ◽

Comprehensive Evaluation ◽

Vertical Mixing ◽

Western Mediterranean ◽

Surface Mixed Layer ◽

Dust Deposition ◽

Near Surface ◽

Surface Ocean ◽

Basin Scale ◽

The Mediterranean

Abstract. Mineral dust deposition is an important supply mechanism for trace elements in the low-latitude ocean. Our understanding of the controls of such inputs has been mostly built on laboratory and surface ocean studies. The lack of direct observations and the tendency to focus on near-surface waters prevent a comprehensive evaluation of the role of dust in oceanic biogeochemical cycles. In the frame of the PEACETIME project (ProcEss studies at the Air-sEa Interface after dust deposition in the MEditerranean sea), the responses of the aluminum (Al) and iron (Fe) cycles to two dust wet deposition events over the central and western Mediterranean Sea were investigated at a timescale of hours to days using a comprehensive dataset gathering dissolved and suspended particulate concentrations, along with sinking fluxes. Dissolved Al (dAl) removal was dominant over dAl released from dust. The Fe / Al ratio of suspended and sinking particles revealed that biogenic particles, and in particular diatoms, were key in accumulating and exporting Al relative to Fe. By combining these observations with published Al / Si ratios of diatoms, we show that adsorption onto biogenic particles, rather than active uptake, represents the main sink for dAl in Mediterranean waters. In contrast, systematic dissolved Fe (dFe) accumulation occurred in subsurface waters (∼ 100–1000 m), while dFe input from dust was only transient in the surface mixed layer. The rapid transfer of dust to depth, the Fe-binding ligand pool in excess to dFe in subsurface (while nearly saturated in surface), and low scavenging rates in this particle-poor depth horizon are all important drivers of this subsurface dFe enrichment. At the annual scale, this previously overlooked mechanism may represent an additional pathway of dFe supply for the surface ocean through diapycnal diffusion and vertical mixing. However, low subsurface dFe concentrations observed at the basin scale (

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Intriguing diversity among diazotrophic picoplankton along a Mediterranean transect: from the origin of plastids to the dominance of rhizobia

Biogeosciences Discussions ◽

10.5194/bgd-7-8779-2010 ◽

2010 ◽

Vol 7 (6) ◽

pp. 8779-8816 ◽

Cited By ~ 2

Author(s):

M. Le Moal ◽

H. Collin ◽

I. C. Biegala

Keyword(s):

Mediterranean Sea ◽

Nifh Gene ◽

Western Mediterranean ◽

Central Mediterranean ◽

Plastid Evolution ◽

Surface Distribution ◽

Western Mediterranean Sea ◽

Diazotrophic Cyanobacteria ◽

The Mediterranean ◽

Marine Areas

Abstract. The Mediterranean Sea is one of the most oligotrophic marine areas on earth where nitrogen fixation has been formally believed to play an important role in carbon and nitrogen fluxes. Although this view is under debate, the diazotrophs responsible for this activity have still not been investigated in the open sea. In this study we characterised the surface distribution and species richness of unicellular and filamentous diazotrophs across the Mediterranean Sea by combining microscopic counts with size fractionated in situ hybridization (TSA-FISH), and 16S rDNA and nifH phylogenies. These genetic analyses were possible owning to the development of a new PCR protocol adapted for scarce microorganisms (0.2 cell ml−1). Low concentrations of diazotrophic cyanobacteria were detected and this community was dominated at 99.9% by picoplankton hybridized with Nitro821 probe, specific for unicellular diazotrophic cyanobacteria (UCYN). Among filamentous cyanobacteria only 0.02 filament ml−1 of Richelia were detected in the eastern basin, while small (0.7–1.5 μm) and large (2.5–3.2 μm) Nitro821-targeted cells were recovered at all stations and averaged 3.5 cell ml−1. The affiliation of the small Nitro821-targeted cells to UCYN-A was confirmed by 16S and nifH phylogenies in the western Mediterranean Sea. Surprisingly, the larger hybridized cells were not belonging to UCYN-B and C but to plastids of picoeukaryote. NifH gene was not recovered among picoeukaryotes, when rhizobia sequences, including the ones of Bradyrhizobia, were dominating nifH clone libraries from picoplanktonic size fractions. Few sequences of γ-proteobacteria were also detected in central Mediterranean Sea. While low phosphate and iron concentrations could explain the absence of Trichodesmium sp., the factors that prevent the development of UCYN-B and C remain unknown. We also propose that the dominating picoplankters probably developed specific strategies, such as associations with protists or particles and photosynthetic activity to acquire carbon for sustaining diazotrophy. Among UCYN further work will be necessary to understand their suggested role in plastid evolution.

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