scholarly journals BGC‐Argo Floats Observe Nitrate Injection and Spring Phytoplankton Increase in the Surface Layer of Levantine Sea (Eastern Mediterranean)

2021 ◽  
Vol 48 (8) ◽  
Author(s):  
F. D'Ortenzio ◽  
V. Taillandier ◽  
H. Claustre ◽  
L. Coppola ◽  
P. Conan ◽  
...  
Keyword(s):  
Surface Layer ◽  
Eastern Mediterranean ◽  
Argo Floats ◽  
Levantine Sea

scholarly journals Hydrology and circulation in the North Aegean (eastern Mediterranean) throughout 1997 and 1998

2002 ◽  
Vol 3 (1) ◽  
pp. 5 ◽  
Author(s):  
V. ZERVAKIS ◽  
D. GEORGOPOULOS
Keyword(s):  
Surface Layer ◽  
Black Sea ◽  
Sea Water ◽  
Saline Water ◽  
Eastern Mediterranean ◽  
Late Summer ◽  
Cyclonic Circulation ◽  
The Black Sea ◽  
The North ◽  
North Aegean

The combination of two research projects offered us the opportunity to perform a comprehensive study of the seasonal evolution of the hydrological structure and the circulation of the North Aegean Sea, at the northern extremes of the eastern Mediterranean. The combination of brackish water inflow from the Dardanelles and the sea-bottom relief dictate the significant differences between the North and South Aegean water columns. The relatively warm and highly saline South Aegean waters enter the North Aegean through the dominant cyclonic circulation of the basin. In the North Aegean, three layers of distinct water masses of very different properties are observed: The 20-50 m thick surface layer is occupied mainly by Black Sea Water, modified on its way through the Bosphorus, the Sea of Marmara and the Dardanelles. Below the surface layer there is warm and highly saline water originating in the South Aegean and the Levantine, extending down to 350-400 m depth. Below this layer, the deeper-than-400 m basins of the North Aegean contain locally formed, very dense water with different θ /S characteristics at each subbasin. The circulation is characterised by a series of permanent, semi-permanent and transient mesoscale features, overlaid on the general slow cyclonic circulation of the Aegean. The mesoscale activity, while not necessarily important in enhancing isopycnal mixing in the region, in combination with the very high stratification of the upper layers, however, increases the residence time of the water of the upper layers in the general area of the North Aegean. As a result, water having out-flowed from the Black Sea in the winter, forms a separate distinct layer in the region in spring (lying between “younger” BSW and the Levantine origin water), and is still traceable in the water column in late summer.

scholarly journals Forecasting circulation in the Cilician Basin of the Levantine Sea

2006 ◽  
Vol 3 (5) ◽  
pp. 1481-1514 ◽  
Author(s):  
E. Özsoy ◽  
A. Sözer
Keyword(s):  
Boundary Conditions ◽  
Initial Conditions ◽  
Eastern Mediterranean ◽  
Model Performance ◽  
Surface Flux ◽  
Mediterranean Coast ◽  
Open Boundary ◽  
Surface Boundary ◽  
Open Boundary Conditions ◽  
Levantine Sea

Abstract. The Cilician Basin/Shelf Model is adapted for studying the shelf circulation in the Cilician Basin – Gulf of İskenderun region of the Levantine Basin of the Eastern Mediterranean between the Turkish Mediterranean coast, Syria and the island of Cyprus. The model initial conditions and open boundary conditions are supplied by the ALERMO regional model of the Levantine Sea, while interactive surface flux boundary conditions are specified by an atmospheric boundary layer sub-model using calculated water properties and surface atmospheric variables supplied by the Skiron atmospheric model, within the nested modelling approach of the MFSTEP (Mediterranean Forecasting System: Towards Environmental Predictions) project. Sensitivity tests are performed for alternative surface boundary conditions. Model performance for shelf/meso-scale forecasts is demonstrated.

scholarly journals Biomarker evidence for nitrogen-fixing cyanobacterial blooms in a brackish surface layer in the Nile River plume during sapropel deposition

Geology ◽  
2019 ◽  
Vol 47 (11) ◽  
pp. 1088-1092 ◽  
Author(s):  
Nicole J. Bale ◽  
Rick Hennekam ◽  
Ellen C. Hopmans ◽  
Denise Dorhout ◽  
Gert-Jan Reichart ◽  
...  
Keyword(s):  
Surface Layer ◽  
Nile Delta ◽  
Eastern Mediterranean ◽  
Cyanobacterial Blooms ◽  
Nile River ◽  
Head Group ◽  
Free Living ◽  
Heterocystous Cyanobacteria ◽  
Primary Core ◽  
Sediment Layers

Abstract Sapropels are organic-rich sediment layers deposited in the eastern Mediterranean Sea during precession minima, resulting from an increase in export productivity and/or preservation. Increased freshwater delivery from the African continent resulted in stratification, causing deepwater anoxia, while nutrient input stimulated productivity, presumably at the deep chlorophyll maximum. Previous studies have suggested that during sapropel deposition, nitrogen fixation was widespread in the highly stratified surface waters, and that cyanobacteria symbiotic with diatoms (diatom-diazotroph associations, DDAs) were responsible. Here we analyzed sapropel S5 sediments for heterocyst glycolipids (HGs) from three locations in the eastern Mediterranean. HG biomarkers can differentiate between those heterocystous cyanobacteria that are free living (found predominately in freshwater or brackish environments) and those that are from DDAs (found in marine settings). In our primary core, from a location which would have been influenced by the Nile River outflow, we detected a HG with a pentose (C5) head group specific for DDAs. However, HGs with a hexose (C6) head group, specific to free-living cyanobacteria, were present in substantially (up to 60×) higher concentration. These data suggest that at our study location, free-living cyanobacteria were the dominant diazotrophs, rather than DDAs. The C6 HGs increased substantially at the onset of sapropel S5 deposition, suggesting that substantial seasonal cyanobacterial blooms were associated with a brackish surface layer flowing from the Nile into the eastern Mediterranean. Two additional S5 sapropels were analyzed, one also from the Nile delta region and one from the region between Libya and southwestern Crete. Overall, comparison of the HG distribution in the three S5 sapropels provides evidence that all three locations were initially influenced by surface salinities that were sufficiently low to support free-living heterocystous cyanobacteria. While free-living heterocystous cyanobacteria continued to outnumber DDAs during sapropel deposition at the two Nile-influenced sites, DDAs, indicators of persistent marine salinities, were the dominant diazotrophs in the upper part of the sapropel at the more westerly site. These results indicate that N2 fixation by free-living cyanobacteria offers an important additional mechanism to stimulate productivity in regions with strong river discharge during sapropel deposition.

Species of the subgenus Minuspio (Polychaeta: Spionidae: Prionospio) from the southern coast of Turkey (Levantine Sea, eastern Mediterranean), with the description of two new species

Zootaxa ◽  
2011 ◽  
Vol 3043 (1) ◽  
pp. 35 ◽  
Author(s):  
ERTAN DAGLI ◽  
MELIH ERTAN ÇINAR
Keyword(s):  
Invasive Species ◽  
Pacific Coast ◽  
Eastern Mediterranean ◽  
Alien Invasive Species ◽  
Valid Species ◽  
Tyrrhenian Sea ◽  
Southern Coast ◽  
Marine Fauna ◽  
Levantine Sea ◽  
Two New Species

Three species belonging to the subgenus Minuspio are described from the southern coast of Turkey. Prionospio (Minuspio) anatolica sp. nov., and Prionospio (Minuspio) maciolekae sp. nov. are new to science and P. (M.) pulchra is a new report for the marine fauna of the Levantine and Black Sea coasts of Turkey. Prionospio (M.) anatolica sp. nov., differs from all other Prionospio (M.) species by the shape of the prostomium, branchiae, and the absence of eyes. This species has 7 pairs of long, apinnate branchiae on chaetigers 2 to 8. Prionospio (M.) maciolekae sp. nov., differs from other Prionospio (M.) species in having short, densely ciliated branchiae and distinct dorsal crests on chaetigers 10–28. The examination of older materials deposited at the Museum of Ege University (ESFM) revealed that Prionospio (M.) pulchra, an alien invasive species, also occurred in the Aegean and Black Seas since 2000. In the Mediterranean, this species seems to be first noticed from the Italian waters (Tyrrhenian Sea, Lago di Sabaudia) and misidentified as Prionospio cirrifera. These species were encountered on a variety of biotopes in the region. In addition, two specimens of P. (M.) multibranchiata collected near the type locality (Bazan Bay, Pacific coast of Canada) were examined and a redescription of this species was made. The morphology, ecology and distribution of these species are given together with a taxonomic key to all valid species of the subgenus Minuspio.

First evidence of a distal early Holocene ash layer in Eastern Mediterranean deep-sea sediments derived from the anatolian volcanic province

2010 ◽  
Vol 73 (3) ◽  
pp. 497-506 ◽  
Author(s):  
Y. Hamann ◽  
S. Wulf ◽  
O. Ersoy ◽  
W. Ehrmann ◽  
E. Aydar ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Volcanic Glass ◽  
Volcanic Field ◽  
Early Holocene ◽  
The South ◽  
Volcanic Province ◽  
Levantine Sea ◽  
Ash Layer

A hitherto unknown distal volcanic ash layer has been detected in a sediment core recovered from the southeastern Levantine Sea (Eastern Mediterranean Sea). Radiometric, stratigraphic and sedimentological data show that the tephra, here termed as S1 tephra, was deposited between 8970 and 8690 cal yr BP. The high-silica rhyolitic composition excludes an origin from any known eruptions of the Italian, Aegean or Arabian volcanic provinces but suggests a prevailing Central Anatolian provenance. We compare the S1 tephra with proximal to medial-distal tephra deposits from well-known Mediterranean ash layers and ash fall deposits from the Central Anatolian volcanic field using electron probe microanalyses on volcanic glass shards and morphological analyses on ash particles. We postulate a correlation with the Early Holocene "Dikkartın" dome eruption of Erciyes Dağ volcano (Cappadocia, Turkey). So far, no tephra of the Central Anatolian volcanic province has been detected in marine sediment archives in the Eastern Mediterranean region. The occurrence of the S1 tephra in the south-eastern part of the Levantine Sea indicates a wide dispersal of pyroclastic material from Erciyes Da? more than 600 km to the south and is therefore an important tephrostratigraphical marker in sediments of the easternmost Mediterranean Sea and the adjacent hinterland.

Microphytoplankton and ciliate communities’ structure and distribution in a stressed area of the south coast of Sfax, Tunisia (eastern Mediterranean Sea)

2016 ◽  
Vol 67 (10) ◽  
pp. 1445 ◽  
Author(s):  
Amira Rekik ◽  
Jannet Elloumi ◽  
Dorra Chaari ◽  
Habib Ayadi
Keyword(s):  
Surface Layer ◽  
Coastal Waters ◽  
Eastern Mediterranean ◽  
Environmental Parameters ◽  
Numerical Density ◽  
Eastern Mediterranean Sea ◽  
Ciliate Abundance ◽  
Ciliate Species ◽  
High Nutrient ◽  
Sediment Interface

The environmental parameters, microphytoplankton and ciliate communities in the area were studied in spring and autumn at 20 stations along the coast south of Sfax over two seasons during 2011. The results showed that the environmental parameters indicated high nutrient levels and their concentrations ranges reported as criteria of eutrophication in coastal waters. A total of 78 microphytoplankton species were identified, belonging to Diatoms, Dinoflagellates, Cyanobacteriae, Euglenophyceae, Dictyochophyceae and Chlorophyceae. The numerical density of phytoplankton was high over the whole area, with season averages between 44.10×102 ±41.93×102 and 103.55×102 ± 107.33×102 cells L–1. A total of 58 ciliate species were identified at all of the stations. Tintinnids abundance was generally higher than naked ciliate abundance reported for autumn and spring seasons, both at the surface layer and water–sediment interface. One striking point was that ciliate abundance was unchanged in autumn (4×102 cells L–1) but was still higher in spring (6×102 cells L–1). Some species reported in this study are commonly found in the stressed coastal waters.

Phytoplankton response to a Lagrangian phosphate addition in the Levantine Sea (Eastern Mediterranean)

2005 ◽  
Vol 52 (22-23) ◽  
pp. 2944-2960 ◽  
Author(s):  
Stella Psarra ◽  
Tamar Zohary ◽  
Michael D. Krom ◽  
R. Fauzi C. Mantoura ◽  
Thalia Polychronaki ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Levantine Sea ◽  
Phosphate Addition

The occurrence of the Atlantic penaeid prawn Farfantepenaeus aztecus (Ives, 1891) in the Thermaikos Gulf (Aegean Sea, eastern Mediterranean): considerations on the potential establishment and impact on the autochthonous Melicertus kerathurus (Forskål, 1775)

Crustaceana ◽  
2014 ◽  
Vol 87 (14) ◽  
pp. 1606-1619 ◽  
Author(s):  
Kosmas Kevrekidis
Keyword(s):  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Western Atlantic ◽  
The North ◽  
Levantine Sea ◽  
Farfantepenaeus Aztecus ◽  
Penaeid Prawn ◽  
North Aegean ◽  
Abiotic And Biotic Factors ◽  
North Aegean Sea

The penaeid prawn Farfantepenaeus aztecus (Ives, 1891), of western Atlantic origin, has been recently recorded in a lagoonal environment in the Thermaikos Gulf (North Aegean Sea) increasing the number of alien decapods in the Aegean Sea to 29. The present work reports the finding of F. aztecus in offshore waters on the trawling ground of the Thermaikos Gulf. The presence of this alien species in the area is probably due to ships’ ballast water or to expansion northward from the Levantine Sea where it was recently reported. The life cycle characteristics and several properties of the Atlantic species along with the abiotic and biotic factors of the Thermaikos indicate that the species will eventually be established successfully in the gulf. However, the potential establishment of F. aztecus in the Thermaikos Gulf raises concerns over the fate of the autochthonous penaeid prawn Melicertus kerathurus (Forskål, 1775) in the North Aegean Sea.

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