scholarly journals Seasonal and inter-annual variability of plankton chlorophyll and primary production in the Mediterranean Sea: a modelling approach

2011 ◽  
Vol 8 (3) ◽  
pp. 5379-5422 ◽  
Author(s):  
P. Lazzari ◽  
C. Solidoro ◽  
V. Ibello ◽  
S. Salon ◽  
A. Teruzzi ◽  
...  
Keyword(s):  
Primary Production ◽  
Mediterranean Sea ◽  
Seasonal Variability ◽  
Net Primary Production ◽  
Eastern Mediterranean ◽  
Light Extinction ◽  
Spatial And Temporal Variability ◽  
Nutrient Loads ◽  
Basin Scale ◽  
The Mediterranean

Abstract. This study presents a model of chlorophyll and primary production in the pelagic Mediterranean Sea. A 3-D-ecosystem model (OPATM-BFM) was adopted to explore specific system characteristics and quantify key biogeochemical variables covering a 6-yr period, from 1999 to 2004. We show that, on a basin scale, the Mediterranean Sea is characterised by a high degree of spatial and temporal variability in terms of primary production and chlorophyll concentrations. On a spatial scale, important horizontal and vertical gradients have been observed. In particular, notable differences between surface net primary production variability and the corresponding vertically integrated production rates have been identified, suggesting that care must be taken when inferring productivity in such systems from satellite observations alone. The present study indicates that seasonal variability dominates inter-annual differences. According to the simulations over a 6-yr period, the developed model correctly simulated the climatological features of deep chlorophyll maxima and chlorophyll west-east gradients, as well as the seasonal variability in the primary offshore regions that were studied. The integrated net primary production highlights north-south gradients that differ from surface net primary production gradients and illustrates the importance of adopting a spatial and temporal description to calculate basin-wide budgets and their variabilities. According to the model, the western Mediterranean, in particular the Alboran Sea, can be considered mesotrophic, whereas the eastern Mediterranean is oligotrophic. Finally, specific simulations that were designed to explore the role of ecosystem boundary conditions were performed. The subsequent results show that the effects of atmospheric and terrestrial nutrient loads on the total integrated net primary production account for less than 5 % of the annual budget, whereas an increase of 30 % in the light extinction factor impacts primary production by approximately 10 %.

scholarly journals Seasonal and inter-annual variability of plankton chlorophyll and primary production in the Mediterranean Sea: a modelling approach

2012 ◽  
Vol 9 (1) ◽  
pp. 217-233 ◽  
Author(s):  
P. Lazzari ◽  
C. Solidoro ◽  
V. Ibello ◽  
S. Salon ◽  
A. Teruzzi ◽  
...  
Keyword(s):  
Primary Production ◽  
Mediterranean Sea ◽  
Net Primary Production ◽  
Eastern Mediterranean ◽  
Light Extinction ◽  
Biogeochemical Model ◽  
Spatial And Temporal Variability ◽  
Nutrient Loads ◽  
Basin Scale ◽  
The Mediterranean

Abstract. This study presents a model of chlorophyll and primary production in the pelagic Mediterranean Sea. A 3-D-biogeochemical model (OPATM-BFM) was adopted to explore specific system characteristics and quantify dynamics of key biogeochemical variables over a 6 yr period, from 1999 to 2004. We show that, on a basin scale, the Mediterranean Sea is characterised by a high degree of spatial and temporal variability in terms of primary production and chlorophyll concentrations. On a spatial scale, important horizontal and vertical gradients have been observed. According to the simulations over a 6 yr period, the developed model correctly simulated the climatological features of deep chlorophyll maxima and chlorophyll west-east gradients, as well as the seasonal variability in the main offshore regions that were studied. The integrated net primary production highlights north-south gradients that differ from surface net primary production gradients and illustrates the importance of resolving spatial and temporal variations to calculate basin-wide budgets and their variability. According to the model, the western Mediterranean, in particular the Alboran Sea, can be considered mesotrophic, whereas the eastern Mediterranean is oligotrophic. During summer stratified period, notable differences between surface net primary production variability and the corresponding vertically integrated production rates have been identified, suggesting that care must be taken when inferring productivity in such systems from satellite observations alone. Finally, specific simulations that were designed to explore the role of external fluxes and light penetration were performed. The subsequent results show that the effects of atmospheric and terrestrial nutrient loads on the total integrated net primary production account for less than 5 % of the its annual value, whereas an increase of 30 % in the light extinction factor impacts primary production by approximately 10 %.

scholarly journals Spatiotemporal variability of alkalinity in the Mediterranean Sea

2015 ◽  
Vol 12 (6) ◽  
pp. 1647-1658 ◽  
Author(s):  
G. Cossarini ◽  
P. Lazzari ◽  
C. Solidoro
Keyword(s):  
Mediterranean Sea ◽  
Seasonal Cycle ◽  
Sea Water ◽  
Eastern Mediterranean ◽  
Surface Flux ◽  
Spatiotemporal Variability ◽  
The Black Sea ◽  
Biogeochemical Model ◽  
Basin Scale ◽  
The Mediterranean

Abstract. The paper provides a basin-scale assessment of the spatiotemporal distribution of alkalinity in the Mediterranean Sea. The assessment is made by integrating the available observations into a 3-D transport–biogeochemical model. The results indicate the presence of complex spatial patterns: a marked west-to-east surface gradient of alkalinity is coupled to secondary negative gradients: (1) from marginal seas (Adriatic and Aegean Sea) to the eastern Mediterranean Sea and (2) from north to south in the western region. The west–east gradient is related to the mixing of Atlantic water entering from the Strait of Gibraltar with the high-alkaline water of the eastern sub-basins, which is correlated to the positive surface flux of evaporation minus precipitation. The north-to-south gradients are related to the terrestrial input and to the input of the Black Sea water through the Dardanelles. In the surface layers, alkalinity has a relevant seasonal cycle (up to 40 μmol kg−1) that is driven by physical processes (seasonal cycle of evaporation and vertical mixing) and, to a minor extent, by biological processes. A comparison of alkalinity vs. salinity indicates that different regions present different relationships: in regions of freshwater influence, the two quantities are negatively correlated due to riverine alkalinity input, whereas they are positively correlated in open sea areas of the Mediterranean Sea.

scholarly journals Pelagic primary production in the coastal Mediterranean Sea: variability, trends, and contribution to basin-scale budgets

2022 ◽  
Vol 19 (1) ◽  
pp. 47-69
Author(s):  
Paula Maria Salgado-Hernanz ◽  
Aurore Regaudie-de-Gioux ◽  
David Antoine ◽  
Gotzon Basterretxea
Keyword(s):  
Primary Production ◽  
Mediterranean Sea ◽  
Coastal Waters ◽  
Carbon Fixation ◽  
Total Carbon ◽  
Climate Indices ◽  
Basin Scale ◽  
Long Term Trends ◽  
The Mediterranean

Abstract. We estimated pelagic primary production (PP) in the coastal (<200 m depth) Mediterranean Sea from satellite-borne data, its contribution to basin-scale carbon fixation, its variability, and long-term trends during the period 2002–2016. Annual coastal PP was estimated at 0.041 Gt C, which approximately represents 12 % of total carbon fixation in the Mediterranean Sea. About 51 % of this production occurs in the eastern basin, whereas the western and Adriatic shelves contribute with ∼25 % each of total coastal production. Strong regional variability is revealed in coastal PP, from high-production areas (>300 g C m−2) associated with major river discharges to less productive provinces (<50 g C m−2) located in the southeastern Mediterranean. PP variability in the Mediterranean Sea is dominated by interannual variations, but a notable basin-scale decline (17 %) has been observed since 2012 concurring with a period of increasing sea surface temperatures in the Mediterranean Sea and positive North Atlantic Oscillation and Mediterranean Oscillation climate indices. Long-term trends in PP reveal slight declines in most coastal areas (−0.05 to −0.1 g C m−2 per decade) except in the Adriatic where PP increases at +0.1 g C m−2 per decade. Regionalization of coastal waters based on PP seasonal patterns reveals the importance of river effluents in determining PP in coastal waters that can regionally increase up to 5-fold. Our study provides insight into the contribution of coastal waters to basin-scale carbon balances in the Mediterranean Sea while highlighting the importance of the different temporal and spatial scales of variability.

scholarly journals Springtime contribution of dinitrogen fixation to primary production across the Mediterranean Sea

Ocean Science ◽  
2013 ◽  
Vol 9 (3) ◽  
pp. 489-498 ◽  
Author(s):  
E. Rahav ◽  
B. Herut ◽  
A. Levi ◽  
M. R. Mulholland ◽  
I. Berman-Frank
Keyword(s):  
Primary Production ◽  
Mediterranean Sea ◽  
N2 Fixation ◽  
Eastern Mediterranean ◽  
Dominant Role ◽  
Early Spring ◽  
Western Basin ◽  
Eastern Basin ◽  
The Mediterranean ◽  
Planktonic Communities

Abstract. Dinitrogen (N2) fixation rates were measured during early spring across the different provinces of Mediterranean Sea surface waters. N2 fixation rates, measured using 15N2 enriched seawater, were lowest in the eastern basin and increased westward with a maximum at the Strait of Gibraltar (0.10 to 2.35 nmol N L−1 d−1, respectively). These rates were 3–7 fold higher than N2 fixation rates measured previously in the Mediterranean Sea during summertime and we estimated that methodological differences alone did not account for the seasonal changes we observed. Higher contribution of N2 fixation to primary production (4–8%) was measured in the western basin compared to the eastern basin (∼2%). Our data indicates that these differences between basins may be attributed to changes in N2-fixing planktonic communities and that heterotrophic diazotrophy may play a significant role in the eastern Mediterranean while autotrophic diazotrophy has a more dominant role in the western basin.

scholarly journals CDOM Spatiotemporal Variability in the Mediterranean Sea: A Modelling Study

2021 ◽  
Vol 9 (2) ◽  
pp. 176
Author(s):  
Paolo Lazzari ◽  
Eva Álvarez ◽  
Elena Terzić ◽  
Gianpiero Cossarini ◽  
Ilya Chernov ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Optical Model ◽  
Eastern Mediterranean ◽  
Spatiotemporal Variability ◽  
Radiative Transfer Model ◽  
Biogeochemical Model ◽  
Transfer Model ◽  
Spatial And Temporal Variability ◽  
Limiting Nutrients ◽  
The Mediterranean

This study investigates the spatial and temporal variability of chromophoric-dissolved organic matter (CDOM) in the Mediterranean Sea. The analysis is carried out using a state-of-the-art 3D biogeochemical model. The model describes the plankton dynamics, the cycles of the most important limiting nutrients, and the particulate and dissolved pools of carbon. The source of CDOM is directly correlated to the dynamics of dissolved organic carbon (DOC) by a fixed production quota. Then CDOM degrades by photobleaching and remineralization. The main innovation of the system is the inclusion of a bio-optical radiative transfer model that computes surface upwelling irradiance, and therefore simulates remotely sensed reflectance (Rrs). Simulation results of three model configurations are evaluated using satellite Rrs, particularly at 412 nm, 443 nm, and 490 nm. All simulations show a winter minimum in Rrs for the considered bands. However, different parameterizations of DOC-release induce a different accumulation of CDOM, especially in the eastern Mediterranean, and a different Rrs signature: a more active microbial loop during summer implies a decrease of Rrs at 412 nm. We demonstrate how the usage of a bio-optical model allows us to corroborate hypotheses on CDOM-cycling based on blue–violet Rrs data, supporting the importance of this complementary data stream with respect to satellite-derived chlorophyll.

scholarly journals Dust deposition in an oligotrophic marine environment: impact on the carbon budget

2014 ◽  
Vol 11 (1) ◽  
pp. 1707-1738 ◽  
Author(s):  
C. Guieu ◽  
C. Ridame ◽  
E. Pulido-Villena ◽  
M. Bressac ◽  
K. Desboeufs ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Atmospheric Deposition ◽  
Mediterranean Sea ◽  
Carbon Budget ◽  
Net Primary Production ◽  
Saharan Dust ◽  
Surface Mixed Layer ◽  
Dust Deposition ◽  
The Mediterranean

Abstract. By bringing new nutrients and particles to the surface ocean, atmospheric deposition impacts biogeochemical cycles. The extent to which those changes are modifying the carbon balance in oligotrophic environments such as the Mediterranean Sea that receives important Saharan dust fluxes is unknown. DUNE project provides the first attempt to evaluate the changes induced in the carbon budget of an oligotrophic system after simulated Saharan dust wet and dry deposition events. Here we report the results for the 3 distinct artificial dust seeding experiments in large mesocosms that were conducted in the oligotrophic waters of the Mediterranean Sea in summer 2008 and 2010. Simultaneous measurements of the metabolic rates (C fixation, C respiration) in the water column have shown that the dust deposition did not change drastically the metabolic balance as the tested waters remained net heterotroph (i.e. net primary production to bacteria respiration ratio < 1) and in some cases the net heterotrophy was even enhanced by the dust deposition. Considering the different terms of the carbon budget, we estimate that it was balanced with a dissolved organic carbon (DOC) consumption of at least 10% of the initial stock. This corresponds to a fraction of the DOC stock of the surface mixed layer that consequently will not be exported during the winter mixing. Although heterotrophic bacteria were found to be the key players in the response to dust deposition, net primary production increased about twice in case of simulated wet deposition (that includes anthropogenic nitrogen) and a small fraction of particulate organic carbon was still exported. Our estimated carbon budgets are an important step forward in the way we understand dust deposition and associated impacts on the oceanic cycles. They are providing knowledge about the key processes (i.e. bacteria respiration, aggregation) that need to be considered for an integration of atmospheric deposition in marine biogeochemical modeling.

scholarly journals Acidification, deoxygenation, nutrient and biomasses decline in a warming Mediterranean Sea

2021 ◽  
Author(s):  
Marco Reale ◽  
Gianpiero Cossarini ◽  
Paolo Lazzari ◽  
Tomas Lovato ◽  
Giorgio Bolzon ◽  
...  
Keyword(s):  
Primary Production ◽  
Mediterranean Sea ◽  
Water Column ◽  
21St Century ◽  
Dissolved Inorganic Carbon ◽  
Net Primary Production ◽  
Eastern Mediterranean ◽  
Marine Ecosystems ◽  
Global Ocean ◽  
Co2 Absorption

Abstract. The projected warming, nutrient decline, changes in net primary production, deoxygenation and acidification of the global ocean will dramatically affect marine ecosystems during the 21st century. Here we assess the climate change-related impacts in the marine ecosystems of the Mediterranean Sea in the middle and at the end of the 21st century using high-resolution projections of the physical and biogeochemical state of the basin under the Representative Concentration Pathways (RCPs) 4.5 and 8.5. The analysis shows significant changes in the dissolved nutrient content of the euphotic and intermediate layers of the basin, net primary production, phytoplankton respiration and carbon stock (including phytoplankton, zooplankton, bacterial biomass and particulate organic matter). The projections also show a uniform surface and subsurface reduction in the oxygen concentration driven by the warming of the water column and by the increase in respiration. Moreover, we observe an acidification in the upper water column, linked to the increase in the dissolved inorganic carbon content of the water column due to CO2 absorption from the atmosphere and the increase in respiration. The projected changes are stronger in the eastern Mediterranean due to the limited influence, in that part of the basin, of the exchanges in the Strait of Gibraltar.

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 Bio-optical characterization of the waters of the Bay of La Paz, southern Gulf of California, during late spring 2004

2020 ◽  
Vol 54 (3) ◽  
pp. 343
Author(s):  
Erik Coria-Monter ◽  
María Adela Monreal-Gómez ◽  
David Alberto Salas de León ◽  
Elizabeth Durán-Campos
Keyword(s):  
Primary Production ◽  
Gulf Of California ◽  
Net Primary Production ◽  
Light Extinction ◽  
La Paz ◽  
Light Extinction Coefficient ◽  
Production Values ◽  
Subsequent Calculation ◽  
Natural Fluorescence ◽  
Community Growth

Information on selected bio-optical properties and primary production values of the waters of the Bay of La Paz, southern Gulf of California, is reported during June 2004, a region characterized to have very rich biodiversity, including endemic and endangered species, with high ecological relevance. In-situ measurements of natural fluorescence and photosynthetically available radiation (PAR) enabled the subsequent calculation of the incident irradiance (E0), the light extinction coefficient (k), compensation depth (Zc) and critical depth (Zcr). The results suggest the presence of light propitious conditions for phytoplankton community growth and net primary production, which are highly significant for the potential development of models of light penetration, ocean color, primary productivity, and analyses of organic carbon energy flow.

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