scholarly journals Enhanced heterotrophic activity in the surface microlayer of the Mediterranean Sea

2005 ◽  
Vol 39 ◽  
pp. 293-302 ◽  
Author(s):  
I Obernosterer ◽  
P Catala ◽  
T Reinthaler ◽  
GJ Herndl ◽  
P Lebaron
Keyword(s):  
Mediterranean Sea ◽  
Surface Microlayer ◽  
Heterotrophic Activity ◽  
The Mediterranean

scholarly journals A Two-Component Parameterization of Marine Ice Nucleating Particles Based on Seawater Biology and Sea Spray Aerosol Measurements in the Mediterranean Sea

2020 ◽  
Author(s):  
Jonathan V. Trueblood ◽  
Alesia Nicosia ◽  
Anja Engel ◽  
Birthe Zäncker ◽  
Matteo Rinaldi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Biological Properties ◽  
Organic Content ◽  
Water Soluble ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Natural Seawater ◽  
Order Of Magnitude ◽  
The Mediterranean

Abstract. Ice nucleating particles (INP) have a large impact on the climate-relevant properties of clouds over the oceans. Studies have shown that sea spray aerosols (SSA), produced upon bursting of bubbles at the ocean surface, can be an important source of marine INP, particularly during periods of enhanced biological productivity. Recent mesocosm experiments using natural seawater spiked with nutrients have revealed that marine INP are derived from two separate classes of organic matter in SSA. Despite this finding, existing parameterizations for marine INP abundance are based solely on single variables such as total organic carbon (TOC) or SSA surface area, which may mask specific trends in the separate classes of INPs. The goal of this paper is to improve the understanding of the connection between ocean biology and marine INP abundance by reporting results from a field study and proposing a new parameterization of marine INP that accounts for the two associated classes of organic matter. The PEACETIME cruise took place from May 10 to June 10, 2017 in the Mediterranean Sea. Throughout the cruise, INP concentrations in the surface microlayer (SML) and in SSA produced using a plunging aquarium apparatus were continuously monitored while surface seawater (SSW) and SML biological properties were measured in parallel. The organic content of artificially generated SSA was also evaluated. A dust wet deposition event that occurred during the cruise increased the INP concentrations measured in the SML by an order of magnitude, in line with increases of iron in the SML and bacterial abundances. Increases of INPs in marine SSA (INPSSA) were not observed before a delay of three days compared to increases in the SML, and are likely a result of a strong influence of bulk SSW INP for the temperatures investigated (T = −18 °C for SSA, T = −16 °C for SSW). Results confirmed that INPSSA are divided into two classes depending on their associated organic matter. Here we find that warm (T ≥ −22 °C) INPSSA concentrations are correlated with water soluble organic matter in the SSA, but also to SSW parameters (POCSSW INPSSW,−16 °C) while cold INPSSA (T 

scholarly journals Characterising the surface microlayer in the Mediterranean Sea: trace metals concentration and microbial plankton abundance

2019 ◽  
Author(s):  
Antonio Tovar-Sánchez ◽  
Araceli Rodríguez-Romero ◽  
Anja Engel ◽  
Birthe Zäncker ◽  
Franck Fu ◽  
...  
Keyword(s):  
Trace Metals ◽  
Mediterranean Sea ◽  
Surface Waters ◽  
Bacterial Community Composition ◽  
Western Mediterranean ◽  
Surface Microlayer ◽  
Dissolved Metals ◽  
Western Mediterranean Sea ◽  
Sea Surface Microlayer ◽  
The Mediterranean

Abstract. The Sea Surface Microlayer (SML) is known to be enriched in trace metals relative to the underlaying water and to harbor diverse microbial communities (i.e. neuston). However, the processes linking metals and biota in the SML are not yet fully understood. In this study, we analyzed the metal (Cd, Co, Cu, Fe, Ni, Mo, V, Zn and Pb) concentrations in aerosol samples, SML (dissolved and total fractions) and in subsurface waters (SSW; dissolved fraction at ~ 1 m depth) from the Western Mediterranean Sea during a cruise in May–June 2017. The bacterial community composition and abundance in the SML and SSW, and the primary production and Chl-a in the SSW were measured simultaneously at all stations during the cruise. Residence times of particulate metals derived from aerosols deposition ranged from a couple of minutes for Co (2.7 ± 0.9 min; more affected by wind conditions) to a few hours for Cu (3.0 ± 1.9 h). Concentration of most dissolved metals in both, the SML and SSW, were well correlated with the salinity gradient and showed the characteristic eastward increase in surface waters of the Mediterranean Sea (MS). Contrarily, the total fraction of some reactive metals in the SML (i.e. Cu, Fe, Pb and Zn) showed negative trends with salinity, these trends of concentrations seem to be associate to microbial uptake. Our results suggest a toxic effect of Ni on neuston and microbiology community’s abundance of the top meter of the surface waters of the Western Mediterranean Sea.

scholarly journals Eukaryotic community composition in the sea surface microlayer across an east-west transect in the Mediterranean Sea

2020 ◽  
Author(s):  
Birthe Zäncker ◽  
Michael Cunliffe ◽  
Anja Engel
Keyword(s):  
Mediterranean Sea ◽  
Community Composition ◽  
Significant Proportion ◽  
Sea Surface ◽  
Surface Microlayer ◽  
Tyrrhenian Sea ◽  
Ionian Sea ◽  
Western Basin ◽  
Sea Surface Microlayer ◽  
The Mediterranean

Abstract. The sea surface microlayer (SML) represents the boundary layer at the air-sea interface. Microbial eukaryotes in the SML potentially influence air-sea gas exchange directly by taking up and producing gases, and indirectly by excreting and degrading organic matter, which may modify the viscoelastic properties of the SML. However, little is known about the controlling factors that influence microbial eukaryote community composition in the SML. We studied the composition of the microbial community, transparent exopolymer particles and polysaccharides in the SML during the PEACETIME cruise along a west-east transect in the Mediterranean Sea, covering the western basin, Tyrrhenian Sea and Ionian Sea. At the stations located in the Ionian Sea, fungi were found in high relative abundances determined by 18S sequencing efforts, making up a significant proportion of the sequences recovered. At the same time, bacterial and phytoplankton counts were decreasing from west to east, while transparent exopolymer particle (TEP) abundance and total carbohydrate (TCHO) concentrations remained the same between Mediterranean basins. Thus, the presence of substrates for fungi, such as Cladosporium known to take up phytoplankton-derived polysaccharides, in combination with decreased substrate competition by bacteria suggests that fungi could be thriving in the neuston of the Ionian Sea.

scholarly journals Wet deposition in the remote western and central Mediterranean as a source of trace metals to surface seawater

2021 ◽  
Author(s):  
Karine Desboeufs ◽  
Franck Fu ◽  
Matthieu Bressac ◽  
Antonio Tovar-Sánchez ◽  
Sylvain Triquet ◽  
...  
Keyword(s):  
Trace Metals ◽  
Mediterranean Sea ◽  
Wet Deposition ◽  
Saharan Dust ◽  
Surface Microlayer ◽  
Dust Deposition ◽  
Central Mediterranean ◽  
Order Of Magnitude ◽  
The Mediterranean ◽  
Atmospheric Inputs

Abstract. This study reports the only recent characterisation of two contrasted wet deposition events collected during the PEACETIME cruise in the Mediterranean open seawater, and their impact on trace metals (TMS) marine stocks. Rain samples were analysed for Al, 12 trace metals (TMs hereafter, including Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrients (N, P, DOC) concentrations. The first rain sample collected in the Ionian Sea (rain ION) was a wet typical regional background deposition event whereas the second rain collected in the Algerian Basin (rain FAST) was a Saharan dust wet deposition. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, suggesting either less anthropogenic influence in the remote Mediterranean environment, or decreased emissions during the last decades in the Mediterranean Sea. The TMs inventories in the surface microlayer and mixed layer (0–20 m) at ION and FAST stations before and after the events, compared to atmospheric fluxes, showed that the atmospheric inputs were a significant source of particulate TMs for both layers. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as marine stocks within the ML for dissolved Fe, Co and Zn, underlining the role of the atmosphere in their biogeochemical cycle in the stratified Mediterranean Sea. In case of intense wet dust deposition event, the contribution of atmospheric inputs could be critical for dissolved stocks of the majority of TMs.

scholarly journals Characterizing the surface microlayer in the Mediterranean Sea: trace metal concentrations and microbial plankton abundance

2020 ◽  
Vol 17 (8) ◽  
pp. 2349-2364 ◽  
Author(s):  
Antonio Tovar-Sánchez ◽  
Araceli Rodríguez-Romero ◽  
Anja Engel ◽  
Birthe Zäncker ◽  
Franck Fu ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Negative Correlation ◽  
Salinity Gradient ◽  
Western Mediterranean ◽  
Surface Microlayer ◽  
Dissolved Metals ◽  
Strong Negative Correlation ◽  
Chl A ◽  
Sea Surface Microlayer ◽  
The Mediterranean

Abstract. The Sea Surface Microlayer (SML) is known to be enriched by trace metals relative to the underlying water and harbor diverse microbial communities (i.e., neuston). However, the processes linking metals and biota in the SML are not yet fully understood. The metal (Cd, Co, Cu, Fe, Ni, Mo, V, Zn and Pb) concentrations in aerosol samples in the SML (dissolved and total fractions) and in subsurface waters (SSWs; dissolved fraction at ∼1 m depth) from the western Mediterranean Sea were analyzed in this study during a cruise in May–June 2017. The composition and abundance of the bacterial community in the SML and SSW, the primary production, and Chl a in the SSW were measured simultaneously at all stations during the cruise. Residence times in the SML of metals derived from aerosol depositions were highly variable and ranged from minutes for Fe (3.6±6.0 min) to a few hours for Cu (5.8±6.2 h). Concentrations of most of the dissolved metals in both the SML and SSW were positively correlated with the salinity gradient and showed the characteristic eastward increase in the surface waters of the Mediterranean Sea (MS). In contrast, the total fraction of some reactive metals in the SML (i.e., Cu, Fe, Pb and Zn) showed a negative correlation with salinity and a positive correlation with microbial abundance, which might be associated with microbial uptake. Our results show a strong negative correlation between the dissolved and total Ni concentration and heterotrophic bacterial abundance in the SML and SSW, but we cannot ascertain whether this correlation reflects a toxicity effect or is the result of some other process.

scholarly journals Spatial gradients in trace metal concentrations in the surface microlayer of the Mediterranean Sea

2014 ◽  
Vol 1 ◽  
Author(s):  
Antonio Tovar-Sánchez ◽  
Jesús M. Arrieta ◽  
Carlos M. Duarte ◽  
Sergio A. Sañudo-Wilhelmy
Keyword(s):  
Trace Metal ◽  
Mediterranean Sea ◽  
Surface Microlayer ◽  
Metal Concentrations ◽  
Spatial Gradients ◽  
The Mediterranean

scholarly journals Eukaryotic community composition in the sea surface microlayer across an east–west transect in the Mediterranean Sea

2021 ◽  
Vol 18 (6) ◽  
pp. 2107-2118
Author(s):  
Birthe Zäncker ◽  
Michael Cunliffe ◽  
Anja Engel
Keyword(s):  
Mediterranean Sea ◽  
Significant Proportion ◽  
Sea Surface ◽  
Surface Microlayer ◽  
Tyrrhenian Sea ◽  
Ionian Sea ◽  
Western Basin ◽  
Microbial Eukaryotes ◽  
Sea Surface Microlayer ◽  
The Mediterranean

Abstract. The sea surface microlayer (SML) represents the boundary layer at the air–sea interface. Microbial eukaryotes in the SML potentially influence air–sea gas exchange directly by taking up and producing gases and indirectly by excreting and degrading organic matter, which may modify the viscoelastic properties of the SML. However, little is known about the distribution of microbial eukaryotes in the SML. We studied the composition of the microbial community, transparent exopolymer particles and polysaccharides in the SML during the PEACETIME cruise along a west–east transect in the Mediterranean Sea, covering the western basin, Tyrrhenian Sea and Ionian Sea. At the stations located in the Ionian Sea, fungi – likely of continental origin and delivered by atmospheric deposition – were found in high relative abundances, making up a significant proportion of the sequences recovered. Concomitantly, bacterial and picophytoplankton counts decreased from west to east, while transparent exopolymer particle (TEP) abundance and total carbohydrate (TCHO) concentrations remained constant in all basins. Our results suggest that the presence of substrates for fungi, such as Cladosporium, known to take up phytoplankton-derived polysaccharides, in combination with decreased substrate competition by bacteria, might favor fungal dominance in the neuston of the Ionian Sea and other low-nutrient, low-chlorophyll (LNLC) regions.

scholarly journals A two-component parameterization of marine ice-nucleating particles based on seawater biology and sea spray aerosol measurements in the Mediterranean Sea

2021 ◽  
Vol 21 (6) ◽  
pp. 4659-4676
Author(s):  
Jonathan V. Trueblood ◽  
Alessia Nicosia ◽  
Anja Engel ◽  
Birthe Zäncker ◽  
Matteo Rinaldi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Mediterranean Sea ◽  
Water Soluble ◽  
Component Model ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Model Based ◽  
Two Component ◽  
The Mediterranean

Abstract. Ice-nucleating particles (INPs) have a large impact on the climate-relevant properties of clouds over the oceans. Studies have shown that sea spray aerosols (SSAs), produced upon bursting of bubbles at the ocean surface, can be an important source of marine INPs, particularly during periods of enhanced biological productivity. Recent mesocosm experiments using natural seawater spiked with nutrients have revealed that marine INPs are derived from two separate classes of organic matter in SSAs. Despite this finding, existing parameterizations for marine INP abundance are based solely on single variables such as SSA organic carbon (OC) or SSA surface area, which may mask specific trends in the separate classes of INP. The goal of this paper is to improve the understanding of the connection between ocean biology and marine INP abundance by reporting results from a field study and proposing a new parameterization of marine INPs that accounts for the two associated classes of organic matter. The PEACETIME cruise took place from 10 May to 10 June 2017 in the Mediterranean Sea. Throughout the cruise, INP concentrations in the surface microlayer (INPSML) and in SSAs (INPSSA) produced using a plunging aquarium apparatus were continuously monitored while surface seawater (SSW) and SML biological properties were measured in parallel. The organic content of artificially generated SSAs was also evaluated. INPSML concentrations were found to be lower than those reported in the literature, presumably due to the oligotrophic nature of the Mediterranean Sea. A dust wet deposition event that occurred during the cruise increased the INP concentrations measured in the SML by an order of magnitude, in line with increases in iron in the SML and bacterial abundances. Increases in INPSSA were not observed until after a delay of 3 days compared to increases in the SML and are likely a result of a strong influence of bulk SSW INPs for the temperatures investigated (T=-18 ∘C for SSAs, T=-15 ∘C for SSW). Results confirmed that INPSSA are divided into two classes depending on their associated organic matter. Here we find that warm (T≥-22 ∘C) INPSSA concentrations are correlated with water-soluble organic matter (WSOC) in the SSAs, but also with SSW parameters (particulate organic carbon, POCSSW and INPSSW,-16C) while cold INPSSA (T<-22 ∘C) are correlated with SSA water-insoluble organic carbon (WIOC) and SML dissolved organic carbon (DOC) concentrations. A relationship was also found between cold INPSSA and SSW nano- and microphytoplankton cell abundances, indicating that these species might be a source of water-insoluble organic matter with surfactant properties and specific IN activities. Guided by these results, we formulated and tested multiple parameterizations for the abundance of INPs in marine SSAs, including a single-component model based on POCSSW and a two-component model based on SSA WIOC and OC. We also altered a previous model based on OCSSA content to account for oligotrophy of the Mediterranean Sea. We then compared this formulation with the previous models. This new parameterization should improve attempts to incorporate marine INP emissions into numerical models.

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