scholarly journals Role of fish herbivory in structuring the vertical distribution of canopy algae Cystoseira spp. in the Mediterranean Sea

2009 ◽  
Vol 375 ◽  
pp. 1-11 ◽  
Author(s):  
A Vergés ◽  
T Alcoverro ◽  
E Ballesteros
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Fish Herbivory ◽  
The Mediterranean ◽  
The Vertical Distribution ◽  
Canopy Algae

scholarly journals Sinking microplastics in the water column: simulations in the Mediterranean Sea

Ocean Science ◽  
2021 ◽  
Vol 17 (2) ◽  
pp. 431-453
Author(s):  
Rebeca de la Fuente ◽  
Gábor Drótos ◽  
Emilio Hernández-García ◽  
Cristóbal López ◽  
Erik van Sebille
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Water Column ◽  
Large Scale ◽  
Circulation Model ◽  
Small Scale ◽  
The Mediterranean ◽  
Scale Turbulence ◽  
Non Gaussian ◽  
The Vertical Distribution

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects (inertia, Coriolis force, small-scale turbulence and variable seawater density), and we bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

scholarly journals On the vertical distribution of the chlorophyll <i>a</i> concentration in the Mediterranean Sea: a basin scale and seasonal approach

2015 ◽  
Vol 12 (5) ◽  
pp. 4139-4181 ◽  
Author(s):  
H. Lavigne ◽  
F. D'Ortenzio ◽  
M. Ribera D'Alcalà ◽  
H. Claustre ◽  
R. Sauzède ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Global Ocean ◽  
Control Procedure ◽  
Chl A ◽  
Basin Scale ◽  
In Situ Experiments ◽  
The Mediterranean ◽  
The Vertical Distribution ◽  
Surface Observations

Abstract. The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, which is mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles calibrated into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a dedicated quality control procedure. To ensure homogeneity between the different data sources, 65% of fluorescence profiles have been inter-calibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profile in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings on the range of [Chl a] values and on the main Mediterranean trophic regimes. It also provides new insights on the seasonal variability of the shape of the vertical [Chl a] profile, inaccessible from remote sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, suggesting thus that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] distribution in the Mediterranean Sea mimics, at smaller scales, what is observed in the Global Ocean. As already evidenced by analyzing satellite surface observations, mid-latitude and subtropical like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears characterized by patterns already observed at global scale.

scholarly journals Sinking microplastics in the water column: simulations in the Mediterranean Sea

2020 ◽  
Author(s):  
Rebeca de la Fuente ◽  
Gábor Drótos ◽  
Emilio Hernández García ◽  
Cristóbal López ◽  
Erik van Sebille
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Water Column ◽  
Large Scale ◽  
Circulation Model ◽  
Small Scale ◽  
The Mediterranean ◽  
Scale Turbulence ◽  
Non Gaussian ◽  
The Vertical Distribution

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects: inertia, Coriolis force, small-scale turbulence and variable seawater density, and bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

scholarly journals Sinking microplastics in the water column: simulations in the Mediterranean Sea

2021 ◽  
Author(s):  
Rebeca de la Fuente ◽  
Gábor Drótos ◽  
Emilio Hernández ◽  
Cristóbal López ◽  
Erik van Sebille
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Water Column ◽  
Large Scale ◽  
Circulation Model ◽  
Small Scale ◽  
The Mediterranean ◽  
Scale Turbulence ◽  
Non Gaussian ◽  
The Vertical Distribution

&lt;p&gt;We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects: inertia, Coriolis force, small-scale turbulence and variable seawater density, and bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.&lt;/p&gt;

scholarly journals Metazooplankton diversity, community structure and spatial distribution across the Mediterranean Sea in summer: evidence of ecoregions

2011 ◽  
Vol 8 (2) ◽  
pp. 3081-3119 ◽  
Author(s):  
A. Nowaczyk ◽  
F. Carlotti ◽  
D. Thibault-Botha ◽  
M. Pagano
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Mesh Size ◽  
Specific Pattern ◽  
Strongly Correlated ◽  
Western Basin ◽  
Order Of Magnitude ◽  
The Mediterranean ◽  
Abundance And Diversity ◽  
The Vertical Distribution

Abstract. The diversity and distribution of metazooplankton across the Mediterranean Sea was studied along a 3000 km long transect from the eastern to the western basins during the BOUM cruise in summer 2008. Metazooplankton were sampled using both a 120 μm mesh size bongo net and Niskin bottles at 17 stations. Here we report on the stock, the composition and the structure of the metazooplankton community. The abundance was 4 to 8 times higher than in several previously published studies, whereas the biomass remained within the same order of magnitude. An eastward decrease in abundance was evident, although biomass was variable. Spatial (horizontal and vertical) distribution of metazooplankton abundance and biomass was strongly correlated to chlorophyll-a concentration. In addition, a clear association was observed between the vertical distribution of nauplii and small copepods and the depth of the deep chlorophyll maximum. The role of environmental factors is also discussed. Cluster analysis allowed us to define a regionalization of the Mediterranean Sea based on the abundance and diversity of metazooplankton. We found a north-south distinction in the western basin and a longitudinal homogeneity in the eastern basin. The Sicily Channel appeared as an intermediate region. The specific pattern of distribution of remarkable species was also described.

scholarly journals Distribution of epipelagic metazooplankton across the Mediterranean Sea during the summer BOUM cruise

2011 ◽  
Vol 8 (8) ◽  
pp. 2159-2177 ◽  
Author(s):  
A. Nowaczyk ◽  
F. Carlotti ◽  
D. Thibault-Botha ◽  
M. Pagano
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Mesh Size ◽  
Strongly Correlated ◽  
Deep Chlorophyll Maximum ◽  
Specific Distribution ◽  
Order Of Magnitude ◽  
The Mediterranean ◽  
The Vertical Distribution ◽  
Horizontal And Vertical Distribution

Abstract. The diversity and distribution of epipelagic metazooplankton across the Mediterranean Sea was studied along a 3000 km long transect from the eastern to the western basins during the BOUM cruise in summer 2008. Metazooplankton were sampled using both a 120 μm mesh size bongo net and Niskin bottles in the upper 200 m layer at 17 stations. Here we report on the stock, the composition and the structure of the metazooplankton community. The abundance was 4 to 8 times higher than in several previously published studies, whereas the biomass remained within the same order of magnitude. An eastward decrease in abundance was evident, although biomass was variable. Spatial (horizontal and vertical) distribution of metazooplankton abundance and biomass was strongly correlated to chlorophyll-a concentration. In addition, a clear association was observed between the vertical distribution of nauplii and small copepods and the depth of the deep chlorophyll maximum. The distinction between the communities of the eastern and western basins was clearly explained by the environmental factors. The specific distribution pattern of remarkable species was also described.

scholarly journals On the vertical distribution of the chlorophyll <i>a</i> concentration in the Mediterranean Sea: a basin-scale and seasonal approach

2015 ◽  
Vol 12 (16) ◽  
pp. 5021-5039 ◽  
Author(s):  
H. Lavigne ◽  
F. D'Ortenzio ◽  
M. Ribera D'Alcalà ◽  
H. Claustre ◽  
R. Sauzède ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Global Ocean ◽  
Control Procedure ◽  
Chl A ◽  
Basin Scale ◽  
In Situ Experiments ◽  
The Mediterranean ◽  
The Vertical Distribution ◽  
Surface Observations

Abstract. The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles converted into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a specific quality control procedure. To ensure homogeneity between the different data sources, 65 % of fluorescence profiles have been intercalibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profiles in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings over the range of existing [Chl a] values and throughout the principal Mediterranean trophic regimes. They also provide new insights into the seasonal variability in the shape of the vertical [Chl a] profile, inaccessible through remote-sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, thus suggesting that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] spatial distribution in the Mediterranean Sea mimics, on smaller scales, what is observed in the global ocean. As already evidenced by analyzing satellite surface observations, midlatitude- and subtropical-like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears to be characterized by patterns already observed on the global scale.

Migration and ‘pull factor’ traps

2020 ◽  
Author(s):  
Glenda Garelli ◽  
Martina Tazzioli
Keyword(s):  
Mediterranean Sea ◽  
Migration Studies ◽  
Pull Factors ◽  
The Past ◽  
Critical Knowledge ◽  
Political Outcomes ◽  
History Of ◽  
The Mediterranean ◽  
History Books

Abstract This article engages with the centrality that the push–pull theory regained in the context of border deaths in the Mediterranean Sea and particularly as part of the debate against the criminalization of nongovernment organizations (NGOs’) rescue missions at sea. The article opens by illustrating the context in which the push–pull theory re-emerged—after having been part of migration studies’ history books for over a decade—as part of an effort to defend non-state actors engaged in rescue missions in the Mediterranean Sea against an aggressive campaign of illegalilzation conducted by European states. We then take a step back to trace the history of the push–pull theory and its role as a foil for critical migration studies in the past 20 years. Building on this history, the article then turns to interrogating the epistemic and political outcomes that result from bringing evidence against the NGOs’ role as pull factors for migrants. The article closes by advocating for a transformative, rather than evidencing, role of critical knowledge in the current political context where migrants and actors who fight against border deaths are increasingly criminalized.

scholarly journals The role of atmospheric deposition in the biogeochemistry of the Mediterranean Sea

1999 ◽  
Vol 44 (1-3) ◽  
pp. 147-190 ◽  
Author(s):  
Stefano Guerzoni ◽  
Roy Chester ◽  
François Dulac ◽  
Barak Herut ◽  
Marie-Dominique Loÿe-Pilot ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Mediterranean Sea ◽  
The Mediterranean
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