scholarly journals Diversity of cultivated and metabolically active aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

2011 ◽  
Vol 8 (3) ◽  
pp. 4421-4457 ◽  
Author(s):  
C. Jeanthon ◽  
D. Boeuf ◽  
O. Dahan ◽  
F. Le Gall ◽  
L. Garczarek ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Phylogenetic Analyses ◽  
Early Summer ◽  
Molecular Methods ◽  
Anoxygenic Phototrophic Bacteria ◽  
Reaction Centre ◽  
Pufm Gene ◽  
The Mediterranean ◽  
Seawater Samples

Abstract. Aerobic anoxygenic phototrophic (AAP) bacteria play significant roles in the bacterioplankton productivity and biogeochemical cycles of the surface ocean. In this study, we applied both cultivation and mRNA-based molecular methods to explore the diversity of AAP bacteria along an oligotrophic gradient in the Mediterranean Sea in early summer 2008. Colony-forming units obtained on three different agar media were screened for the production of bacteriochlorophyll-a (BChl-a), the light-harvesting pigment of AAP bacteria. BChl-a-containing colonies represented a low part of the cultivable fraction. In total, 52 AAP strains were isolated and the phylogenetic analyses based on their 16S rRNA and pufM genes showed that they were all affiliated to the Alphaproteobacteria. The most frequently isolated strains belonged to Citromicrobium bathyomarinum, and Erythrobacter and Roseovarius species. Most other isolates were related to species not reported to produce BChl-a and/or may represent novel taxa. Direct extraction of RNA from seawater samples enabled the analysis of the expression of pufM, the gene coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis. Clone libraries of pufM gene transcripts revealed that most phylotypes were highly similar to sequences previously recovered from the Mediterranean Sea and a large majority (~94%) was affiliated with the Gammaproteobacteria. The most abundantly detected phylotypes occurred in the western and eastern Mediterranean basins. However, some were exclusively detected in the eastern basin, reflecting the highest diversity of pufM transcripts observed in this ultra-oligotrophic region. To our knowledge, this is the first study to document extensively the diversity of AAP isolates and to unveil the active AAP community in an oligotrophic marine environment. By pointing out the discrepancies between culture-based and molecular methods, this study highlights the existing gaps in the understanding of the AAP bacteria ecology, especially in the Mediterranean Sea and likely globally.

scholarly journals Diversity of cultivated and metabolically active aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

2011 ◽  
Vol 8 (7) ◽  
pp. 1955-1970 ◽  
Author(s):  
C. Jeanthon ◽  
D. Boeuf ◽  
O. Dahan ◽  
F. Le Gall ◽  
L. Garczarek ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Phylogenetic Analyses ◽  
Early Summer ◽  
Molecular Methods ◽  
Anoxygenic Phototrophic Bacteria ◽  
Reaction Centre ◽  
Pufm Gene ◽  
The Mediterranean ◽  
Seawater Samples

Abstract. Aerobic anoxygenic phototrophic (AAP) bacteria play significant roles in the bacterioplankton productivity and biogeochemical cycles of the surface ocean. In this study, we applied both cultivation and mRNA-based molecular methods to explore the diversity of AAP bacteria along an oligotrophic gradient in the Mediterranean Sea in early summer 2008. Colony-forming units obtained on three different agar media were screened for the production of bacteriochlorophyll-a (BChl-a), the light-harvesting pigment of AAP bacteria. BChl-a-containing colonies represented a low part of the cultivable fraction. In total, 54 AAP strains were isolated and the phylogenetic analyses based on their 16S rRNA and pufM genes showed that they were all affiliated to the Alphaproteobacteria. The most frequently isolated strains belonged to Citromicrobium bathyomarinum, and Erythrobacter and Roseovarius species. Most other isolates were related to species not reported to produce BChl-a and/or may represent novel taxa. Direct extraction of RNA from seawater samples enabled the analysis of the expression of pufM, the gene coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis. Clone libraries of pufM gene transcripts revealed that most phylotypes were highly similar to sequences previously recovered from the Mediterranean Sea and a large majority (~94 %) was affiliated to the Gammaproteobacteria. The most abundantly detected phylotypes occurred in the western and eastern Mediterranean basins. However, some were exclusively detected in the eastern basin, reflecting the highest diversity of pufM transcripts observed in this ultra-oligotrophic region. To our knowledge, this is the first study to document extensively the diversity of AAP isolates and to unveil the active AAP community in an oligotrophic marine environment. By pointing out the discrepancies between culture-based and molecular methods, this study highlights the existing gaps in the understanding of the AAP bacteria ecology, especially in the Mediterranean Sea and likely globally.

scholarly journals Ecology of aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

2011 ◽  
Vol 8 (4) ◽  
pp. 973-985 ◽  
Author(s):  
D. Lamy ◽  
C. Jeanthon ◽  
M. T. Cottrell ◽  
D. L. Kirchman ◽  
F. Van Wambeke ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Bacterial Growth ◽  
Growth Response ◽  
Anoxygenic Phototrophic Bacteria ◽  
Carbon Limitation ◽  
Organic Substrates ◽  
Western Basin ◽  
Eastern Basin ◽  
Nutrient Additions ◽  
The Mediterranean

Abstract. Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basin of the Mediterranean Sea and were linked with concentrations of chlorophyll-a, nutrient and dissolved organic carbon. Inorganic nutrient and glucose additions to surface seawater samples along the oligotrophic gradient revealed that AAP bacteria were nitrogen- and carbon-limited in the ultraoligotrophic eastern basin. The intensity of the AAP bacterial growth response generally differed from that of the total bacterial growth response. BChl-a quota of AAP bacterial communities was significantly higher in the eastern basin than in the western basin, suggesting that reliance on phototrophy varied along the oligotrophic gradient and that nutrient and/or carbon limitation favors BChl-a synthesis.

scholarly journals The Conflict Between Greece And Turkey In The Mediterranean Sea (International Maritime Law Study)

Jurnal Hukum ◽  
2020 ◽  
Vol 36 (2) ◽  
pp. 126
Author(s):  
Edanur Yıldız
Keyword(s):  
International Law ◽  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
East Mediterranean ◽  
International Courts ◽  
Maritime Law ◽  
The Mediterranean

Turkey and Greece are again dragged into a new conflict in the East Mediterranean. Turkey and Greece vie for supremacy in the eastern Mediterranean. Turkey, for its part, indicated that Greece's claim to the territory would amount to a siege in the country by giving Greece a disproportionate amount of territory. This study aims to rethink the conflict between Greece and Turkey in the waters of the Mediterranean sea in the view of international maritime law. This study uses an empirical juridical approach. The Result of this research is Turkey does not ignore the Greece rights, Greece ignores the international law with its extended or excessive maritime claims. Greece tries to give full entitlement of the islands in Mediterranean and Agean. Whereas the effect Formula is applied by international courts.

scholarly journals Characterization of Coolia spp. (Gonyaucales, Dinophyceae) from Southern Tunisia: first record of Coolia malayensis in the Mediterranean Sea

ALGAE ◽  
2021 ◽  
Vol 36 (3) ◽  
pp. 175-193
Author(s):  
Moufida Abdennadher ◽  
Amel Bellaaj Zouari ◽  
Walid Medhioub ◽  
Antonella Penna ◽  
Asma Hamza
Keyword(s):  
Electron Microscopy ◽  
Mediterranean Sea ◽  
Phylogenetic Trees ◽  
Eastern Mediterranean ◽  
First Record ◽  
Morphological Characterization ◽  
Mucus Production ◽  
Rdna Sequences ◽  
The Mediterranean ◽  
Morphological Differences

This study provides the first report of the presence of Coolia malayensis in the Mediterranean Sea, co-occurring with C. monotis. Isolated strains from the Gulf of Gabès, Tunisia (South-eastern Mediterranean) were identified by morphological characterization and phylogenetic analysis. Examination by light and scanning electron microscopy revealed no significant morphological differences between the Tunisian isolates and other geographically distant strains of C. monotis and C. malayensis. Phylogenetic trees based on ITS1-5.8S-ITS2 and D1‒D3/28S rDNA sequences showed that C. monotis strains clustered with others from the Mediterranean and Atlantic whereas the C. malayensis isolate branched with isolates from the Pacific and the Atlantic, therefore revealing no geographical trend among C. monotis and C. malayensis populations. Ultrastructural analyses by transmission electron microscopy revealed the presence of numerous vesicles containing spirally coiled fibers in both C. malayensis and C. monotis cells, which we speculate to be involved in mucus production.

scholarly journals High diversified benthic habitats in a tidal Mediterranean sub-tropical environment: the case of the Gulf of Gabès (Tunisia)

2018 ◽  
Author(s):  
Abir Fersi ◽  
Nawfel Mosbahi ◽  
Ali Bakalem ◽  
Jean-Philippe Pezy ◽  
Alexandrine Baffreau ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Tropical Environment ◽  
Gulf Of Gabes ◽  
Annual Cycles ◽  
Gulf Of Gabès ◽  
Zostera Noltei ◽  
Sediment Types ◽  
The Mediterranean ◽  
The Impact

The Gulf of Gabès on the southern coasts of Tunisia in the central part of the Mediterranean is a very shallow basin, characterized by semidiurnal tides, attaining a range of 2.3 m during spring tides. The intertidal zone was covered by extended Zostera (Zosterella) noltei Hornemann, 1832 beds mainly developed around the Kneiss Islands while tidal channels ensured the water circulation in this sub-tropical environment with very low freshwater input and high summer temperature. In spite of protected conventions, the area remained under high human pressures: overfishing, and the impact of the pollution of the phosphate industry. Intensive sampling in both intertidal and shallow subtidal zones during annual cycles permitted to identify a rich macrofauna which increase considerably the species known in this eastern part of the Mediterranean Sea. More than 50 species are added for the Tunisian fauna. Moreover, patterns of diversity are analysed with the sediment types, presence or absence of Zostera noltei seagrass bed, and human pressures. The list of the collected species are compared with those of surrounding areas in both Western and Eastern Mediterranean Sea.

scholarly journals The effect of cyclones crossing the Mediterranean region on sea level anomalies at the Mediterranean Sea coast

2019 ◽  
Author(s):  
Piero Lionello ◽  
Dario Conte ◽  
Marco Reale
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Eastern Mediterranean ◽  
Storm Track ◽  
Western Mediterranean ◽  
Residual Water ◽  
Positive Anomaly ◽  
Western Basin ◽  
Sea Level Anomalies ◽  
The Mediterranean

Abstract. Large positive and negative sea level anomalies at the coast of the Mediterranean Sea are linked to intensity and position of cyclones moving along the Mediterranean storm track, with dynamics involving different factors. This analysis is based on a model hindcast and considers nine coastal stations, which are representative of sea level anomalies with different magnitude and characteristics. When a shallow water fetch is present, the wind around the cyclone center is the main cause of sea level positive and negative anomalies, depending on its onshore or offshore direction. The inverse barometer effect produces a positive anomaly at the coast near the cyclone pressure minimum and a negative anomaly at the opposite side of the Mediterranean Sea, because a cross-basin mean sea level pressure gradient is associated to the presence of a cyclone. Further, at some stations, negative sea level anomalies are reinforced by a residual water mass redistribution within the basin, which is associated with a transient response to the atmospheric pressure forcing. Though the link between presence of a cyclone in the Mediterranean has comparable importance for positive and negative anomalies, the relation between cyclone position and intensity is stronger for the magnitude of positive events. Area of cyclogenesis, track of the central minimum and position at the time of the event differ depending on the location where the sea level anomaly occurs and on its sign. The western Mediterranean is the main cyclogenesis area for both positive and negative anomalies, overall. Atlantic cyclones mainly produce positive sea level anomalies in the western basin. At the easternmost stations, positive anomalies are caused by Cyclogenesis in the Eastern Mediterranean. North Africa cyclogeneses are a major source of positive anomalies at the central African coast and negative anomalies at the eastern Mediterranean and North Aegean coast.

Local adaptation of a Lessepsian invader species to winter conditions in the Mediterranean Sea

2021 ◽  
Author(s):  
Débora Silva Raposo ◽  
Raphaël Morard ◽  
Christiane Schmidt ◽  
Michal Kucera
Keyword(s):  
Quantum Yield ◽  
Mediterranean Sea ◽  
Red Sea ◽  
Photosynthetic Activity ◽  
Eastern Mediterranean ◽  
Effective Quantum Yield ◽  
Mediterranean Populations ◽  
Cold Temperatures ◽  
Invasion Front ◽  
The Mediterranean

<p>In recent decades the “Lessepsian” migration caused a rapid change in the marine community composition due to the invasion of alien species from the Red Sea into the Mediterranean Sea. Among these invaders is the large benthic foraminifera <em>Amphistegina lobifera</em>, a diatom-bearing species that recently reached the invasion front in Sicily. There it copes with colder winters and broader temperature than in its original source, the Red Sea. It is not yet known how (or if) the population from the invasion front has developed adaptation to this new thermal regime. Understanding the modern marine invasive patterns is a crucial tool to predict future invasive successes in marine environments. Therefore, in this study we aim to evaluate the physiological responses to cold temperatures of <em>A. lobifera</em> populations at three different invasive stages: source (Red Sea), early invader (Eastern Mediterranean) and invasion front (Sicily). For this, we conducted a culturing experiment in which we monitored the responses of the foraminifera (growth, motility) to temperatures of 10, 13, 16, 19°C + control (25°C) over four weeks. To address what is the role of their endosymbionts in the adaptation process, we also monitored their photosynthetic activity (Pulse Amplitude Modulation - PAM fluorometer) during the experiment. The growth rate of the foraminifera was reduced for all populations below 19°C as well as the motility, reduced until 16°C and dropping to zero below 13°C. The response of the endosymbionts was however different. There was a reduced photosynthetic activity of the Red Sea and Eastern Mediterranean populations at colder temperatures observed by the lower maximum quantum yield (Fv:Fm) and effective quantum yield (Y(II)), when compared to their initial levels and to the other treatments. In the meantime, the endosymbionts of the Sicily population stood out with the highest photosynthetic activity (Fv:Fm and Y(II)) in the treatments bellow 13 °C (P < 0.05). In conclusion, we observed that while the host responses were similar between the three populations, the endosymbionts from the invasion front population shows the best performance at colder temperatures. This suggests that the photo-symbiosis has an important role in adaptation, most likely being a key factor to the success of past and future migrations.</p>

scholarly journals Characterizing the Evolution of the Container Traffic Share in the Mediterranean Sea Using Hierarchical Clustering

2018 ◽  
Vol 6 (4) ◽  
pp. 121 ◽  
Author(s):  
Manel Grifoll ◽  
Thanassis Karlis ◽  
M. Ortego
Keyword(s):  
Mediterranean Sea ◽  
Hierarchical Clustering ◽  
System Analysis ◽  
Compositional Data ◽  
Eastern Mediterranean ◽  
Compositional Data Analysis ◽  
Mediterranean Countries ◽  
The Mediterranean ◽  
Combination Of Methods ◽  
Port Infrastructure

This research investigates the traffic share evolution of the container throughput in the Mediterranean ports from 2000 to 2015 considering hierarchical clustering and concentration indexes. Compositional Data analysis techniques are used to illustrate periods with similar traffic share composition. Two different regions (East and West) in the Mediterranean Sea (Med) are selected in the function of the long haul services. The standard concentration indexes (i.e., concentration ratio, Gini coefficient, and Normalized Herfindahl-Hirschman) reveal a gentle decreasing of the concentration with relevant fluctuations mainly in the East region. This is due to the investment in port infrastructure in the area resulting from privatization initiatives in many Eastern Mediterranean countries. The periods obtained from the hierarchical clustering show a differentiated pattern in traffic share composition. For these periods, the shift-share results are consistent with traffic fluctuations and in line with the evolution of the concentration indexes. The combination of methods has allowed a good interpretation of the spatial and temporal evolution of the Med ports’ traffic being the methodology applicable elsewhere in the context of port system analysis.

Investigating the amphiatlantic status of Facelina bostoniensis (Couthouy, 1838) (Nudibranchia: Aeolidida)

2020 ◽  
Vol 86 (1) ◽  
pp. 64-71
Author(s):  
Leila Carmona
Keyword(s):  
Mediterranean Sea ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Mitochondrial Cytochrome ◽  
Molecular Systematic ◽  
Dna Sequence Data ◽  
Eastern Atlantic Ocean ◽  
The Mediterranean

ABSTRACT The aeolid species Facelina bostoniensis (Couthouy, 1838) was originally described from Massachusetts and was later reported from the Eastern Atlantic Ocean and the Mediterranean Sea. So far, no molecular systematic study of its amphiatlantic status has been carried out. Phylogenetic analyses (maximum likelihood and Bayesian) of DNA sequence data for the mitochondrial cytochrome c oxidase subunit I and 16S rRNA genes confirm the amphiatlantic status of F. bostoniensis. My findings show that this species is restricted to the Atlantic realm and that the species recorded from the Mediterranean is not F. bostoniensis but F. vicina (Bergh, 1882). It is hypothesized that previous records of F. bostoniensis from the Mediterranean Sea were actually misidentifications of F. vicina.

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