scholarly journals Saharan Dust Deposition Effects on the Microbial Food Web in the Eastern Mediterranean: A Study Based on a Mesocosm Experiment

2017 ◽  
Vol 4 ◽  
Author(s):  
Paraskevi Pitta ◽  
Maria Kanakidou ◽  
Nikolaos Mihalopoulos ◽  
Sylvia Christodoulaki ◽  
Panagiotis D. Dimitriou ◽  
...  
Keyword(s):  
Food Web ◽  
Eastern Mediterranean ◽  
Mesocosm Experiment ◽  
Saharan Dust ◽  
Microbial Food Web ◽  
Dust Deposition

scholarly journals Microbial food web dynamics in response to a Saharan dust event: results from a mesocosm study in the oligotrophic Mediterranean Sea

2014 ◽  
Vol 11 (19) ◽  
pp. 5607-5619 ◽  
Author(s):  
E. Pulido-Villena ◽  
A.-C. Baudoux ◽  
I. Obernosterer ◽  
M. Landa ◽  
J. Caparros ◽  
...  
Keyword(s):  
Food Web ◽  
Mediterranean Sea ◽  
Bacterial Abundance ◽  
Bacterial Community Composition ◽  
Saharan Dust ◽  
Microbial Food Web ◽  
Heterotrophic Nanoflagellates ◽  
Bacterial Respiration ◽  
Dust Deposition ◽  
The Impact

Abstract. The significant impact of dust deposition on heterotrophic bacterial dynamics in the surface oligotrophic ocean has recently been evidenced. Considering the central role of bacteria in the microbial loop, it is likely that dust deposition also affects the structure and the functioning of the whole microbial food web. In the frame of the DUNE project, aiming to estimate the impact of dust deposition on the oligotrophic Mediterranean Sea through mesocosm experiments, the main goal of the present paper was to assess how two successive dust deposition events affect the dynamics of the microbial food web. The first dust seeding delivered new P and N to the amended mesocosms and resulted in a pronounced stimulation of bacterial respiration. It also induced pronounced, but transient, changes in the bacterial community composition. No significant effects were observed on the abundances of viruses and heterotrophic nanoflagellates. The second dust seeding also delivered new P and N to the amended mesocosms, but the effect on the microbial food web was very different. Bacterial respiration remained constant and bacterial abundance decreased. Compositional changes following the second seeding were minor compared to the first one. The decrease in bacterial abundance coincided with an increase in virus abundance, resulting in higher virus:bacteria ratios throughout the second seeding period. Our study shows that dust deposition to the surface oligotrophic ocean may involve important modifications of the trophic links among the components of the microbial food web with presumed consequences on C and nutrient cycling.

scholarly journals Microbial food web dynamics in response to a Saharan dust event: results from a mesocosm study in the oligotrophic Mediterranean Sea

2014 ◽  
Vol 11 (1) ◽  
pp. 337-371 ◽  
Author(s):  
E. Pulido-Villena ◽  
A.-C. Baudoux ◽  
I. Obernosterer ◽  
M. Landa ◽  
J. Caparros ◽  
...  
Keyword(s):  
Food Web ◽  
Mediterranean Sea ◽  
Bacterial Abundance ◽  
Bacterial Community Composition ◽  
Saharan Dust ◽  
Microbial Food Web ◽  
Heterotrophic Nanoflagellates ◽  
Bacterial Respiration ◽  
Dust Deposition ◽  
The Impact

Abstract. The significant impact of dust deposition on heterotrophic bacterial dynamics in the surface oligotrophic ocean has recently been evidenced. Considering the central role of bacteria in the microbial loop, it is likely that dust deposition also affects the structure and the functioning of the whole microbial food web. In the frame of the DUNE project, aiming to estimate the impact of dust deposition on the oligotrophic Mediterranean Sea through mesocosm experiments, the main goal of the present paper was to assess how two successive dust deposition events affect the dynamics of the microbial food web. The first dust seeding delivered new P and N to the amended mesocosms and resulted in a pronounced stimulation of bacterial respiration. It also induced pronounced, but transient, changes in the bacterial community composition. No significant effects were observed on the abundances of viruses and heterotrophic nanoflagellates. The second dust seeding also delivered new P and N to the amended mesocosms but the effect on the microbial food web was very different. Bacterial respiration remained constant and bacterial abundance decreased. Compositional changes following the second seeding were minor compared to the first one. The decrease in bacterial abundance coincided with an increase in virus abundance, resulting in higher virus: bacteria ratios throughout the second seeding period. Our study shows that dust deposition to the surface oligotrophic ocean may involve important modifications of the trophic links among the components of the microbial food web with presumed consequences on C and nutrient cycling.

scholarly journals Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean Sea

2012 ◽  
Vol 9 (12) ◽  
pp. 19199-19243 ◽  
Author(s):  
V. Giovagnetti ◽  
C. Brunet ◽  
F. Conversano ◽  
F. Tramontano ◽  
I. Obernosterer ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Phytoplankton Community ◽  
Phytoplankton Bloom ◽  
Community Response ◽  
Mesocosm Experiment ◽  
Saharan Dust ◽  
Dust Deposition ◽  
Layer System ◽  
Pigment Analysis ◽  
The Mediterranean

Abstract. In this study, we investigate the phytoplankton community response, with emphasis on ecophysiology and succession, after two experimental additions of Saharan dust in the surface layer of a low-nutrient low-chlorophyll ecosystem in the Mediterranean Sea. Three mesocosms were amended with evapocondensed dust to simulate realistic Saharan dust events while three additional mesocosms were kept unamended and served as controls. Experiments consisted in two consecutive dust additions and samples were daily collected at different depths (−0.1, −5 and −10 m) during one week, starting before each addition occurred. Data concerning HPLC pigment analysis on two size classes (< 3 and > 3 µm), electron transport rate (ETR) versus irradiance curves, non-photochemical fluorescence quenching (NPQ) and phytoplankton cell abundance (measured by flow cytometry), are presented and discussed in this paper. Results show that picophytoplankton mainly respond to the first dust addition, while the second addition leads to an increase of both pico- and nano-/microphytoplankton. Ecophysiological changes in the phytoplankton community are revealed, and an increase in NPQ development, as well as in pigment concentration per cell, follows the dust additions. ETR does not show large variations between dust-amended and control conditions, while biomass increases in response to the dust additions. Furthermore, the biomass increase observed during this mesocosm experiment allows us to attempt a quantitative assessment and parameterization of the onset of a phytoplankton bloom in a nutrient-limited ecosystem. These results are discussed focusing on the adaptation of picophytoplankton to such a nutrient-limited mixed layer system, as well as on size-dependent competition ability in phytoplankton.

scholarly journals Dust–air pollution dynamics over the Eastern Mediterranean

2015 ◽  
Vol 15 (5) ◽  
pp. 7493-7534
Author(s):  
M. Abdelkader ◽  
S. Metzger ◽  
M. Astitha ◽  
Z. Levin ◽  
J. Lelieveld
Keyword(s):  
Air Pollution ◽  
Atmospheric Chemistry ◽  
Climate Model ◽  
Eastern Mediterranean ◽  
Tropospheric Chemistry ◽  
Saharan Dust ◽  
Back Trajectory ◽  
Dust Deposition ◽  
Dust Transport ◽  
Frontal Systems

Abstract. Interactions of desert dust and air pollution over the Eastern Mediterranean (EM) have been studied, focusing on two distinct dust transport events on 22 and 28 September 2011. The atmospheric chemistry–climate model EMAC has been used at about 50 km grid spacing, applying an online dust emission scheme and calcium as a proxy for dust reactivity. EMAC includes a detailed tropospheric chemistry mechanism, aerosol microphysics and thermodynamics schemes to describe dust "aging". The model is evaluated using ground-based observations for aerosol concentrations and aerosol optical depth as well as satellite observations. Simulation results and back trajectory analysis show that the development of synoptic disturbances over the EM can enhance dust transport from the Sahara and Arabian deserts in frontal systems that also carry air pollution to the EM. The frontal systems are associated with precipitation that control the dust removal. Our results show the importance of chemical aging and deposition of the dust during transport. The relatively long travel periods of Saharan dust result in more sustained aging compared to Arabian dust. Sensitivity simulations indicate three times more rapid dust deposition of aged relative to pristine dust, which significantly decreases the dust lifetime and loading.

scholarly journals Mediterranean basin-wide correlations between Saharan dust deposition and ocean chlorophyll concentration

2012 ◽  
Vol 9 (7) ◽  
pp. 8611-8639 ◽  
Author(s):  
R. Gallisai ◽  
F. Peters ◽  
S. Basart ◽  
J. M. Baldasano
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Chlorophyll Concentration ◽  
Time Lag ◽  
Saharan Dust ◽  
Phytoplankton Production ◽  
Dust Deposition ◽  
Central Mediterranean ◽  
Concentration Data ◽  
The Mediterranean

Abstract. The fertilizing potential of atmospheric deposition on ocean production in the Mediterranean is a matter of debate. In this study, eight years (from 2000 to 2007) of weekly chlorophyll concentration data derived from SeaWiFS satellite observations and dust deposition data provided by the BSC-DREAM8b model are investigated in a basin-wide scale in the Mediterranean Sea to describe the geographical distribution and dynamics of both variables and to find potential relationships between them. In all analyses the largest positive cross correlation values are found with a time lag of 0 8-d periods. The coupling between annual cycles of chlorophyll and dust deposition may on average explain an 11.5% in chlorophyll variation in a large part of the Mediterranean. The Eastern Mediterranean shows the largest annual correlations, while the responsiveness to large events is small. The contrary is true for the Western and Northwestern Mediterranean where, if anything, only large events may add to the chlorophyll variability. The Central Mediterranean shows the highest responsiveness of chlorophyll to mineral dust deposition with annual contributions from seasonal variability as well as stimulations owing to large events. These results highlight the importance of dust deposition from African and Middle East origin in the potential stimulation of phytoplankton production in the nutrient depleted surface layers of the Mediterranean Sea.

scholarly journals Corrigendum: Bacterial Growth and Mortality after Deposition of Saharan Dust and Mixed Aerosols in the Eastern Mediterranean Sea: A Mesocosm Experiment

2017 ◽  
Vol 4 ◽  
Author(s):  
Anastasia Tsiola ◽  
Tatiana M. Tsagaraki ◽  
Antonia Giannakourou ◽  
Nikolaos Nikolioudakis ◽  
Nebil Yücel ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Bacterial Growth ◽  
Eastern Mediterranean ◽  
Mesocosm Experiment ◽  
Saharan Dust ◽  
Eastern Mediterranean Sea

Silicate and labile DOC interfere in structuring the microbial food web via algal-bacterial competition for mineral nutrients: Results of a mesocosm experiment

2003 ◽  
Vol 48 (1) ◽  
pp. 129-140 ◽  
Author(s):  
Harry Havskum ◽  
T. Frede Thingstad ◽  
Renate Scharek ◽  
Francesc Peters ◽  
Elisa Berdalet ◽  
...  
Keyword(s):  
Food Web ◽  
Mineral Nutrients ◽  
Mesocosm Experiment ◽  
Microbial Food Web ◽  
Bacterial Competition

scholarly journals Dust–air pollution dynamics over the eastern Mediterranean

2015 ◽  
Vol 15 (16) ◽  
pp. 9173-9189 ◽  
Author(s):  
M. Abdelkader ◽  
S. Metzger ◽  
R. E. Mamouri ◽  
M. Astitha ◽  
L. Barrie ◽  
...  
Keyword(s):  
Air Pollution ◽  
Eastern Mediterranean ◽  
Tropospheric Chemistry ◽  
Saharan Dust ◽  
Dust Particles ◽  
Back Trajectory ◽  
Dust Deposition ◽  
Dust Transport ◽  
Frontal Systems ◽  
Scavenging Efficiency

Abstract. Interactions of desert dust and air pollution over the eastern Mediterranean (EM) have been studied, focusing on two distinct dust transport events on 22 and 28 September 2011. The atmospheric chemistry–climate model EMAC has been used at about 50 km grid spacing, applying an online dust emission scheme and calcium as a proxy for dust reactivity. EMAC includes a detailed tropospheric chemistry mechanism, aerosol microphysics and thermodynamics schemes to describe dust "aging". The model is evaluated using ground-based observations for aerosol concentrations and aerosol optical depth (AOD) as well as satellite observations. Simulation results and back trajectory analysis show that the development of synoptic disturbances over the EM can enhance dust transport from the Sahara and Arabian deserts in frontal systems that also carry air pollution to the EM. The frontal systems are associated with precipitation that controls the dust removal. Our results show the importance of chemical aging of dust, which increases particle size, dust deposition and scavenging efficiency during transport, overall reducing the lifetime relative to non-aged dust particles. The relatively long travel periods of Saharan dust result in more sustained aging compared to Arabian dust. Sensitivity simulations indicate 3 times more dust deposition of aged relative to pristine dust, which significantly decreases the dust lifetime and loading.

Sign in / Sign up

Export Citation Format

Share Document