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 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 New Evidence of Mediterranean Climate Change and Variability from Sea Surface Temperature Observations

2020 ◽  
Vol 12 (1) ◽  
pp. 132 ◽  
Author(s):  
Andrea Pisano ◽  
Salvatore Marullo ◽  
Vincenzo Artale ◽  
Federico Falcini ◽  
Chunxue Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Mediterranean Sea ◽  
Sea Surface ◽  
Western Basin ◽  
Mean Values ◽  
The Mediterranean ◽  
The Impact ◽  
Northeastern Atlantic

Estimating long-term modifications of the sea surface temperature (SST) is crucial for evaluating the current state of the oceans and to correctly assess the impact of climate change at regional scales. In this work, we analyze SST variations within the Mediterranean Sea and the adjacent Northeastern Atlantic box (west of the Strait of Gibraltar) over the last 37 years, by using a satellite-based dataset from the Copernicus Marine Environment Monitoring Service (CMEMS). We found a mean warming trend of 0.041 ± 0.006 ∘ C/year over the whole Mediterranean Sea from 1982 to 2018. The trend has an uneven spatial pattern, with values increasing from 0.036 ± 0.006 ∘ C/year in the western basin to 0.048 ± 0.006 ∘ C/year in the Levantine–Aegean basin. The Northeastern Atlantic box and the Mediterranean show a similar trend until the late 1990s. Afterwards, the Mediterranean SST continues to increase, whereas the Northeastern Atlantic box shows no significant trend, until ~2015. The observed change in the Mediterranean Sea affects not only the mean trend but also the amplitude of the Mediterranean seasonal signal, with consistent relative increase and decrease of summer and winter mean values, respectively, over the period considered. The analysis of SST changes occurred during the “satellite era” is further complemented by reconstructions also based on direct in situ SST measurements, i.e., the Extended Reconstructed SST (ERSST) and the Hadley Centre Sea Ice and Sea Surface Temperature dataset (HadISST), which go back to the 19th century. The analysis of these longer time series, covering the last 165 years, indicates that the increasing Mediterranean trend, observed during the CMEMS operational period, is consistent with the Atlantic Multidecadal Oscillation (AMO), as it closely follows the last increasing period of AMO. This coincidence occurs at least until 2007, when the apparent onset of the decreasing phase of AMO is not seen in the Mediterranean SST evolution.

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.

The Bridge on the Strait of Messina: “Lowering” the Right of Innocent Passage?

2001 ◽  
Vol 50 (2) ◽  
pp. 411-419 ◽  
Author(s):  
Fabio Spadi
Keyword(s):  
Mediterranean Sea ◽  
Tyrrhenian Sea ◽  
Ionian Sea ◽  
The West ◽  
Minimum Depth ◽  
The Mediterranean ◽  
The Right

The Strait of Messina is a body of water in the Mediterranean Sea separating the island of Sicily to the west from mainland Italy to the east, linking the Lower Tyrrhenian Sea with the Ionian Sea. The strait is around 30 miles long and its width ranges from 13/4 miles (between Faro Point and the Rock of Scylla) to 10 miles (between Cape Alì and Cape Pellaro). At its northern end it reaches, at one point, a minimum depth of 70 metres.1

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 Succession of the sea-surface microlayer in the coastal Baltic Sea under natural and experimentally induced low-wind conditions

2010 ◽  
Vol 7 (9) ◽  
pp. 2975-2988 ◽  
Author(s):  
C. Stolle ◽  
K. Nagel ◽  
M. Labrenz ◽  
K. Jürgens
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Baltic Sea ◽  
Community Composition ◽  
Temporal Variability ◽  
Sea Surface ◽  
Surface Microlayer ◽  
Clear Understanding ◽  
Carbon And Nitrogen ◽  
Sea Surface Microlayer

Abstract. The sea-surface microlayer (SML) is located within the boundary between the atmosphere and hydrosphere. The high spatial and temporal variability of the SML's properties, however, have hindered a clear understanding of interactions between biotic and abiotic parameters at or across the air-water interface. Among the factors changing the physical and chemical environment of the SML, wind speed is an important one. In order to examine the temporal effects of minimized wind influence, SML samples were obtained from the coastal zone of the southern Baltic Sea and from mesocosm experiments in a marina to study naturally and artificially calmed sea surfaces. Organic matter concentrations as well as abundance, 3H-thymidine incorporation, and the community composition of bacteria in the SML (bacterioneuston) compared to the underlying bulk water (ULW) were analyzed. In all SML samples, dissolved organic carbon and nitrogen were only slightly enriched and showed low temporal variability, whereas particulate organic carbon and nitrogen were generally greatly enriched and highly variable. This was especially pronounced in a dense surface film (slick) that developed during calm weather conditions as well as in the artificially calmed mesocosms. Overall, bacterioneuston abundance and productivity correlated with changing concentrations of particulate organic matter. Moreover, changes in the community composition in the field study were stronger in the particle-attached than in the non-attached bacterioneuston. This implies that decreasing wind enhances the importance of particle-attached assemblages and finally induces a succession of the bacterial community in the SML. Eventually, under very calm meteorological conditions, there is an uncoupling of the bacterioneuston from the ULW.

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