scholarly journals Modelled interannual variability of vertical organic matter export related to phytoplankton bloom dynamics – a case-study for the NW Mediterranean Sea

2012 ◽  
Vol 9 (7) ◽  
pp. 9091-9124
Author(s):  
R. Bernardello ◽  
J. G. Cardoso ◽  
N. Bahamon ◽  
D. Donis ◽  
I. Marinov ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Interannual Variability ◽  
Phytoplankton Bloom ◽  
Three Dimensional ◽  
Biogeochemical Model ◽  
Export Flux ◽  
The North ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. Mid-latitude spring blooms of phytoplankton show considerable year-to-year variability in timing, spatial extent and intensity. It is still unclear to what degree the bloom variability is connected to the magnitude of the vertical flux of organic matter. A coupled three-dimensional hydrodynamic-biogeochemical model is used to relate interannual variability in phytoplankton spring-bloom dynamics to variability in the vertical export of organic matter in the NW Mediterranean Sea. Simulation results from 2001 to 2010, validated against remote sensing chlorophyll, show marked interannual variability in both timing and shape of the bloom. Model results show a tendency for the bloom to start later after cold and windy winters. However, the onset of the bloom occurs often when the mixed layer is still several hundred meters deep while the heat flux is already approaching zero. Frequency and intensity of wind episodes control both timing and development of the bloom and the consequent export flux of organic matter. The wintertime flux is greater than zero and shows relatively low interannual variability. The magnitude of this variability is mainly determined in March when the frequency of windy days correlates positively with the export flux. Frequent wind-driven mixing episodes act to increase the export flux and, at the same time, to interrupt the bloom. Our analysis shows that years with discontinuous, low-chlorophyll blooms are likely to have higher export flux than years with undisturbed intense blooms. The area of the study shows strong analogy with the part of the North Atlantic within the same latitude range. Hence, our results may be applicable to quantitatively more important areas of the world oceans.

scholarly journals Factors controlling interannual variability of vertical organic matter export and phytoplankton bloom dynamics – a numerical case-study for the NW Mediterranean Sea

2012 ◽  
Vol 9 (11) ◽  
pp. 4233-4245 ◽  
Author(s):  
R. Bernardello ◽  
J. G. Cardoso ◽  
N. Bahamon ◽  
D. Donis ◽  
I. Marinov ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Interannual Variability ◽  
Phytoplankton Bloom ◽  
World Ocean ◽  
Low Frequency ◽  
Biogeochemical Model ◽  
Export Flux ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. Mid-latitude spring blooms of phytoplankton show considerable year-to-year variability in timing, spatial extent and intensity. It is still unclear to what degree the bloom variability is connected to the magnitude of the vertical flux of organic matter. A coupled three-dimensional hydrodynamic-biogeochemical model is used to relate interannual variability in phytoplankton spring-bloom dynamics to variability in the vertical export of organic matter in the NW Mediterranean Sea. Simulation results from 2001 to 2010, validated against remote-sensing chlorophyll, show marked interannual variability in both timing and shape of the bloom. Model results show a tendency for the bloom to start later after cold and windy winters. However, the onset of the bloom occurs often when the mixed layer is still several hundred metres deep while the heat flux is already approaching zero and turbulent mixing is low. Frequency and intensity of wind episodes control both the timing and development of the bloom and the consequent export flux of organic matter. The wintertime flux is greater than zero and shows relatively low interannual variability. The magnitude of the interannual variability is mainly determined in March when the frequency of windy days positively correlates with the export flux. Frequent wind-driven mixing episodes act to increase the export flux and, at the same time, to interrupt the bloom. Perhaps counterintuitively, our analysis shows that years with discontinuous, low-chlorophyll blooms are likely to have higher export flux than years with intense uninterrupted blooms. The NW Mediterranean shows strong analogy with the North Atlantic section within the same latitude range. Hence, our results may also be applicable to this quantitatively more important area of the world ocean.

Riverine transport of terrestrial organic matter to the North Catalan margin, NW Mediterranean Sea

2013 ◽  
Vol 118 ◽  
pp. 71-80 ◽  
Author(s):  
Anna Sanchez-Vidal ◽  
Marina Higueras ◽  
Eugènia Martí ◽  
Camino Liquete ◽  
Antoni Calafat ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Terrestrial Organic Matter ◽  
The North ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea ◽  
Riverine Transport

Composition and provenance of terrigenous organic matter transported along submarine canyons in the Gulf of Lion (NW Mediterranean Sea)

2013 ◽  
Vol 118 ◽  
pp. 81-94 ◽  
Author(s):  
Catalina Pasqual ◽  
Miguel A. Goñi ◽  
Tommaso Tesi ◽  
Anna Sanchez-Vidal ◽  
Antoni Calafat ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Submarine Canyons ◽  
Terrigenous Organic Matter ◽  
Gulf Of Lion ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

7000 years of paleostorm activity in the NW Mediterranean Sea in response to Holocene climate events

2012 ◽  
Vol 77 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Pierre Sabatier ◽  
Laurent Dezileau ◽  
Christophe Colin ◽  
Louis Briqueu ◽  
Frédéric Bouchette ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
North Atlantic ◽  
Clay Mineralogy ◽  
Mediterranean Coast ◽  
Ice Age ◽  
Storm Activity ◽  
The North ◽  
Nw Mediterranean ◽  
The North Atlantic ◽  
Nw Mediterranean Sea

A high-resolution record of paleostorm events along the French Mediterranean coast over the past 7000 years was established from a lagoonal sediment core in the Gulf of Lions. Integrating grain size, faunal analysis, clay mineralogy and geochemistry data with a chronology derived from radiocarbon dating, we recorded seven periods of increased storm activity at 6300–6100, 5650–5400, 4400–4050, 3650–3200, 2800–2600, 1950–1400 and 400–50 cal yr BP (in the Little Ice Age). In contrast, our results show that the Medieval Climate Anomaly (1150–650 cal yr BP) was characterised by low storm activity.The evidence for high storm activity in the NW Mediterranean Sea is in agreement with the changes in coastal hydrodynamics observed over the Eastern North Atlantic and seems to correspond to Holocene cooling in the North Atlantic. Periods of low SSTs there may have led to a stronger meridional temperature gradient and a southward migration of the westerlies. We hypothesise that the increase in storm activity during Holocene cold events over the North Atlantic and Mediterranean regions was probably due to an increase in the thermal gradient that led to an enhanced lower tropospheric baroclinicity over a large Central Atlantic-European domain.

scholarly journals Pseudo-nitzschia spp. (Bacillariophyceae) and dissolved organic matter (DOM) dynamics in the Ebro Delta (Alfacs Bay, NW Mediterranean Sea)

2009 ◽  
Vol 83 (4) ◽  
pp. 539-549 ◽  
Author(s):  
Sofia Loureiro ◽  
Esther Garcés ◽  
Margarita Fernández-Tejedor ◽  
Dolors Vaqué ◽  
Jordi Camp
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Mediterranean Sea ◽  
Ebro Delta ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

scholarly journals Organic biomarkers in deep-sea regions affected by bottom trawling: pigments, fatty acids, amino acids and carbohydrates in surface sediments from the La Fonera (Palamós) Canyon, NW Mediterranean Sea

2013 ◽  
Vol 10 (12) ◽  
pp. 8093-8108 ◽  
Author(s):  
E. Sañé ◽  
J. Martín ◽  
P. Puig ◽  
A. Palanques
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Organic Matter ◽  
Mediterranean Sea ◽  
Deep Sea ◽  
Bottom Trawling ◽  
Sediment Reworking ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. Deep-sea ecosystems are in general adapted to a limited variability of physical conditions, resulting in high vulnerability and slow recovery rates from anthropogenic perturbations such as bottom trawling. Commercial trawling is the most recurrent and pervasive of human impacts on the deep-sea floor, but studies on its consequences on the biogeochemistry of deep-sea sediments are still scarce. Pigments, fatty acids, amino acids and carbohydrates were analysed in sediments from the flanks of the La Fonera (Palamós) submarine canyon (NW Mediterranean Sea), where a commercial bottom trawling fishery has been active for more than 70 yr. More specifically, we investigated how trawling-induced sediment reworking affects the quality of sedimentary organic matter which reaches the seafloor and accumulates in the sediment column, which is fundamental for the development of benthic communities. Sediment samples were collected during two oceanographic cruises in spring and autumn 2011. The sampled sites included trawl fishing grounds as well as pristine (control) areas. We report that bottom trawling in the flanks of the La Fonera Canyon has caused an alteration of the quality of the organic matter accumulated in the upper 5 cm of the seafloor. The use of a wide pool of biochemical tracers characterized by different reactivity to degradation allowed for us to discriminate the long-term effects of trawl-induced sediment reworking from the natural variability caused by the seasonal cycle of production and sinking of biogenic particles. Differences between untrawled and trawled areas were evidenced by labile amino acids, while differences between spring and autumn samples were detected only by the more labile indicators chlorophyll a and monounsaturated fatty acids. These results suggest that changes in the biochemical composition of the sedimentary organic matter caused by bottom trawling can be more relevant than those associated with natural seasonality and pose serious concerns about the ecological sustainability of deep-sea trawling activities.

scholarly journals Bioavailability of sinking organic matter in the Blanes canyon and the adjacent open slope (NW Mediterranean Sea)

2013 ◽  
Vol 10 (5) ◽  
pp. 3405-3420 ◽  
Author(s):  
P. Lopez-Fernandez ◽  
S. Bianchelli ◽  
A. Pusceddu ◽  
A. Calafat ◽  
A. Sanchez-Vidal ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Deep Sea ◽  
Phytoplankton Bloom ◽  
Statistical Tests ◽  
Sea Surface ◽  
Submarine Canyons ◽  
Entire Study ◽  
Sea Floor ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. Submarine canyons are sites of intense energy and material exchange between the shelf and the deep adjacent basins. To test the hypothesis that active submarine canyons represent preferential conduits of available food for the deep-sea benthos, two mooring lines were deployed at 1200 m depth from November 2008 to November 2009 inside the Blanes canyon and on the adjacent open slope (Catalan Margin, NW Mediterranean Sea). We investigated the fluxes, biochemical composition and food quality of sinking organic carbon (OC). OC fluxes in the canyon and the open slope varied among sampling periods, though not consistently in the two sites. In particular, while in the open slope the highest OC fluxes were observed in August 2009, in the canyon the highest OC fluxes occurred in April–May 2009. For almost the entire study period, the OC fluxes in the canyon were significantly higher than those in the open slope, whereas OC contents of sinking particles collected in the open slope were consistently higher than those in the canyon. This result confirms that submarine canyons are effective conveyors of OC to the deep sea. Particles transferred to the deep sea floor through the canyons are predominantly of inorganic origin, significantly higher than that reaching the open slope at a similar water depth. Using multivariate statistical tests, two major clusters of sampling periods were identified: one in the canyon that grouped trap samples collected in December 2008, concurrently with the occurrence of a major storm at the sea surface, and associated with increased fluxes of nutritionally available particles from the upper shelf. Another cluster grouped samples from both the canyon and the open slope collected in March 2009, concurrently with the occurrence of the seasonal phytoplankton bloom at the sea surface, and associated with increased fluxes of total phytopigments. Our results confirm the key ecological role of submarine canyons for the functioning of deep-sea ecosystems, and highlight the importance of canyons in linking episodic storms and primary production occurring at the sea surface to the deep sea floor.

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