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

2013 ◽  
Vol 10 (5) ◽  
pp. 2973-2991 ◽  
Author(s):  
V. Giovagnetti ◽  
C. Brunet ◽  
F. Conversano ◽  
F. Tramontano ◽  
I. Obernosterer ◽  
...  
Keyword(s):  
Surface Water ◽  
Mediterranean Sea ◽  
Phytoplankton Community ◽  
Phytoplankton Bloom ◽  
Water Layer ◽  
Surface Water Layer ◽  
Saharan Dust ◽  
Dust Deposition ◽  
Pigment Analysis ◽  
The Mediterranean

Abstract. In this study, we investigate the response of the phytoplankton community, with emphasis on ecophysiology and succession, after two experimental additions of Saharan dust in the surface water 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. The experiment 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) vs. 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 occur, with NPQ and pigment concentration per cell increasing after dust additions. While biomass increases after pulses of new nutrients, ETR does not greatly vary between dust-amended and control conditions, in relation with ecophysiological changes within the phytoplankton community, such as the increase in NPQ and pigment cellular concentration. A quantitative assessment and parameterisation of the onset of a phytoplankton bloom in a nutrient-limited ecosystem is attempted on the basis of the increase in phytoplankton biomass observed during the experiment. The results of this study are discussed focusing on the adaptation of picophytoplankton to nutrient limitation in the surface water layer, as well as on size-dependent competition ability in phytoplankton.

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 Saharan Dust Deposition May Affect Phytoplankton Growth in the Mediterranean Sea at Ecological Time Scales

PLoS ONE ◽  
2014 ◽  
Vol 9 (10) ◽  
pp. e110762 ◽  
Author(s):  
Rachele Gallisai ◽  
Francesc Peters ◽  
Gianluca Volpe ◽  
Sara Basart ◽  
José Maria Baldasano
Keyword(s):  
Mediterranean Sea ◽  
Time Scales ◽  
Phytoplankton Growth ◽  
Saharan Dust ◽  
Dust Deposition ◽  
The Mediterranean

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 Structure and function of epipelagic mesozooplankton and their response to dust deposition events during the spring PEACETIME cruise in the Mediterranean Sea

2020 ◽  
Vol 17 (21) ◽  
pp. 5417-5441 ◽  
Author(s):  
Guillermo Feliú ◽  
Marc Pagano ◽  
Pamela Hidalgo ◽  
François Carlotti
Keyword(s):  
Mediterranean Sea ◽  
Size Fraction ◽  
Zooplankton Community ◽  
Saharan Dust ◽  
Taxonomic Structure ◽  
Dust Event ◽  
Dust Deposition ◽  
Filter Feeders ◽  
The Mediterranean ◽  
Dust Events

Abstract. The PEACETIME cruise (May–June 2017) was a basin-scale survey covering the Provencal, Algerian, Tyrrhenian, and Ionian basins during the post-spring bloom period and was dedicated to tracking the impact of Saharan dust deposition events on the Mediterranean Sea pelagic ecosystem. Two such events occurred during this period, and the cruise strategy allowed for the study of the initial phase of the ecosystem response to one dust event in the Algerian Basin (during 5 d at the so-called “FAST long-duration station”) as well as the study of a latter response to another dust event in the Tyrrhenian Basin (by sampling from 5 to 12 d after the deposition). This paper documents the structural and functional patterns of the zooplankton component during this survey, including their responses to these two dust events. The mesozooplankton were sampled at 12 stations using nets with two different mesh sizes (100 and 200 µm) that were mounted on a Bongo frame for vertical hauls within the depth layer from 0 to 300 m. The Algerian and Tyrrhenian basins were found to be quite similar in terms of hydrological and biological variables, which clearly differentiated them from the northern Provencal Basin and the eastern Ionian Basin. In general, total mesozooplankton showed reduced variations in abundance and biomass values over the whole area, with a noticeable contribution from the small size fraction (<500 µm) of up to 50 % with respect to abundance and 25 % with respect to biomass. This small size fraction makes a significant contribution (15 %–21 %) to the mesozooplankton fluxes (carbon demand, grazing pressure, respiration, and excretion), which is estimated using allometric relationships to the mesozooplankton size spectrum at all stations. The taxonomic structure was dominated by copepods, mainly cyclopoid and calanoid copepods, and was completed by appendicularians, ostracods, and chaetognaths. Zooplankton taxa assemblages, analyzed using multivariate analysis and rank frequency diagrams, slightly differed between basins, which is in agreement with recently proposed Mediterranean regional patterns. However, the strongest changes in the zooplankton community were linked to the abovementioned dust deposition events. A synoptic analysis of the two dust events observed in the Tyrrhenian and Algerian basins, based on the rank frequency diagrams and a derived index proposed by Mouillot and Lepretre (2000), delivered a conceptual model of a virtual time series of the zooplankton community responses after a dust deposition event. The initial phase before the deposition event (state 0) was dominated by small-sized cells consumed by their typical zooplankton filter feeders (small copepods and appendicularians). The disturbed phase during the first 5 d following the deposition event (state 1) then induced a strong increase in filter feeders and grazers of larger cells as well as the progressive attraction of carnivorous species, leading to a sharp increase in the zooplankton distribution index. Afterward, this index progressively decreased from day 5 to day 12 following the event, highlighting a diversification of the community (state 2). A 3-week delay was estimated for the index to return to its initial value, potentially indicating the recovery time of a Mediterranean zooplankton community after a dust event. To our knowledge, PEACETIME is the first in situ study that has allowed for the observation of mesozooplankton responses before and soon after natural Saharan dust depositions. The change in the rank frequency diagrams of the zooplankton taxonomic structure is an interesting tool to highlight short-term responses of zooplankton to episodic dust deposition events. Obviously dust-stimulated pelagic productivity impacts up to mesozooplankton in terms of strong but short changes in taxa assemblages and trophic structure, with potential implications for oligotrophic systems such as the Mediterranean Sea.

scholarly journals Wet deposition in the remote western and central Mediterranean as a source of trace metals to surface seawater

2021 ◽  
Author(s):  
Karine Desboeufs ◽  
Franck Fu ◽  
Matthieu Bressac ◽  
Antonio Tovar-Sánchez ◽  
Sylvain Triquet ◽  
...  
Keyword(s):  
Trace Metals ◽  
Mediterranean Sea ◽  
Wet Deposition ◽  
Saharan Dust ◽  
Surface Microlayer ◽  
Dust Deposition ◽  
Central Mediterranean ◽  
Order Of Magnitude ◽  
The Mediterranean ◽  
Atmospheric Inputs

Abstract. This study reports the only recent characterisation of two contrasted wet deposition events collected during the PEACETIME cruise in the Mediterranean open seawater, and their impact on trace metals (TMS) marine stocks. Rain samples were analysed for Al, 12 trace metals (TMs hereafter, including Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrients (N, P, DOC) concentrations. The first rain sample collected in the Ionian Sea (rain ION) was a wet typical regional background deposition event whereas the second rain collected in the Algerian Basin (rain FAST) was a Saharan dust wet deposition. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, suggesting either less anthropogenic influence in the remote Mediterranean environment, or decreased emissions during the last decades in the Mediterranean Sea. The TMs inventories in the surface microlayer and mixed layer (0–20 m) at ION and FAST stations before and after the events, compared to atmospheric fluxes, showed that the atmospheric inputs were a significant source of particulate TMs for both layers. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as marine stocks within the ML for dissolved Fe, Co and Zn, underlining the role of the atmosphere in their biogeochemical cycle in the stratified Mediterranean Sea. In case of intense wet dust deposition event, the contribution of atmospheric inputs could be critical for dissolved stocks of the majority of TMs.

scholarly journals Process studies at the air-sea interface after atmospheric deposition in the Mediterranean Sea: objectives and strategy of the PEACETIME oceanographic campaign (May–June 2017)

2020 ◽  
Author(s):  
Cécile Guieu ◽  
Fabrizio D'Ortenzio ◽  
François Dulac ◽  
Vincent Taillandier ◽  
Andrea Doglioli ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Mediterranean Sea ◽  
Saharan Dust ◽  
Anthropogenic Sources ◽  
Dust Deposition ◽  
Process Studies ◽  
In Situ Observations ◽  
The Mediterranean ◽  
First Time

Abstract. In spring, the Mediterranean Sea, a well-stratified low nutrient low chlorophyll region, receives atmospheric deposition both desert dust from the Sahara and airborne particles from anthropogenic sources. Such deposition translates into a supply of new nutrients and trace metals for the surface waters that likely impact biogeochemical cycles. However, the quantification of the impacts and the processes involved are still far from being assessed in situ. In this paper, we provide a state of the art regarding dust deposition and its impact on the Mediterranean Sea biogeochemistry and we describe in this context the objectives and strategy of the PEACETIME project and cruise, entirely dedicated to filling this knowledge gap. Our strategy to go a step forward than in previous approaches in understanding these impacts by catching a real deposition event at sea is detailed. The PEACETIME oceanographic campaign took place in May–June 2017 and we describe how we were able to successfully adapt the planned transect in order to sample a Saharan dust deposition event, thanks to a dedicated strategy, so-called Fast Action. That was successful, providing, for the first time in our knowledge, a coupled atmospheric and oceanographic sampling before, during and after an atmospheric deposition event. Atmospheric and marine in situ observations and process studies have been conducted in contrasted area and we summarize the work performed at sea, the type of data acquired and their valorization in the papers published in the special issue.

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 Longitudinal variability of the biogeochemical role of Mediterranean aerosols in the Mediterranean Sea

2011 ◽  
Vol 8 (5) ◽  
pp. 1067-1080 ◽  
Author(s):  
E. Ternon ◽  
C. Guieu ◽  
C. Ridame ◽  
S. L'Helguen ◽  
P. Catala
Keyword(s):  
Mediterranean Sea ◽  
Forest Fires ◽  
Saharan Dust ◽  
Aerosol Sampling ◽  
Modest Contribution ◽  
Anthropogenic Contribution ◽  
The Mediterranean ◽  
June July ◽  
Atmospheric Inputs ◽  
Longitudinal Variability

Abstract. The Mediterranean Sea is a semi-enclosed basin characterized by a strong thermal stratification during summer during which the atmosphere is the main source of new nutrients to the nutrient-depleted surface layer. From aerosol sampling and microcosm experiments performed during the TransMed BOUM cruise (June–July 2008) we showed that: (i) the Mediterranean atmosphere composition (Al, Fe, P) was homogeneous over ~28° of longitude and was a mixture with a constant proportion of anthropogenic contribution and a variable but modest contribution of crustal aerosols. This quite stable composition over a one month period and a long transect (~2500 km) allowed to define the Mediterranean atmospheric "background" that characterizes the summer season in the absence of major Saharan event and forest fires, (ii) primary production significantly increased at all tested stations after aerosols addition collected on-board and after Saharan dust analog addition, indicating that both additions relieved on-going (co)-limitations. Although both additions significantly increased the N2 fixation rates at the western station, diazotrophic activity remained very low (~0.2 nmol N L−1 d−1), (iii) due to the presence of anthropogenic particles, the probable higher solubility of nutrients associated with mixed aerosols (crustal + anthropogenic contribution), conferred a higher fertilizing potential to on-board collected aerosol as compared to Saharan dust analog. Finally, those experiments showed that atmospheric inputs from a mixed atmospheric event ("summer rain" type) or from a high-intensity Saharan event would induce comparable response by the biota in the stratified Mediterranean SML, during summer.

Sign in / Sign up

Export Citation Format

Share Document