scholarly journals Short-term temporal variations of heterotrophic bacterial abundance and production in the open NW Mediterranean Sea

2008 ◽  
Vol 5 (3) ◽  
pp. 1899-1932 ◽  
Author(s):  
G. Mével ◽  
M. Vernet ◽  
J. F. Ghiglione
Keyword(s):  
Mediterranean Sea ◽  
Time Scale ◽  
Bacterial Abundance ◽  
Temporal Dynamics ◽  
Bacterial Biomass ◽  
Tight Coupling ◽  
Production Values ◽  
Nw Mediterranean ◽  
Wind Events ◽  
Nw Mediterranean Sea

Abstract. We present the vertical and temporal dynamics of total vs. particle-attached bacterial abundance and activity over a 5 week period under summer to autumn transition in NW Mediterranean Sea. By comparison to previous investigations in the same area but during different seasons, we found that total bacterial biomass and production values were consistent with the hydrological conditions of the summer-fall transition. At a weekly time scale, total bacterial biomass and production in the euphotic layers was significantly correlated with phytoplanktonic biomass. At an hourly time scale, total bacterial biomass responded very rapidly to chlorophyll-a fluctuations, suggesting a tight coupling between phytoplankton and bacteria for resource partitioning during summer-autumn transition. In contrast, no influence of diel changes on bacterial parameters was detected. Episodic events such as coastal water intrusions had a significant positive effect on total bacterial abundance and production, whereas we could not detect any influence of short wind events whatever the magnitude. Finally, we show that particle-attached bacteria can represent a large proportion (until 49%) of the total bacterial activity in the euphotic layer but display rapid and sporadic changes at hourly time scales. This study underlines the value of large datasets covering different temporal scales to clarify the biogeochemical role of bacteria in the cycling of organic matter in open seawater.

scholarly journals Seasonal to hour variation scales in abundance and production of total and particle-attached bacteria in the open NW Mediterranean Sea (0–1000 m)

2008 ◽  
Vol 5 (6) ◽  
pp. 1573-1586 ◽  
Author(s):  
G. Mével ◽  
M. Vernet ◽  
M. Goutx ◽  
J. F. Ghiglione
Keyword(s):  
Mediterranean Sea ◽  
Time Scale ◽  
Bacterial Abundance ◽  
Temporal Dynamics ◽  
Bacterial Biomass ◽  
Tight Coupling ◽  
Attached Bacteria ◽  
Nw Mediterranean ◽  
Wind Events ◽  
Nw Mediterranean Sea

Abstract. We present the vertical and temporal dynamics of total vs. particle-attached bacterial abundance and activity over a 5 week period under summer to autumn transition in NW Mediterranean Sea. At a weekly time scale, total bacterial biomass and production in the euphotic layers was significantly correlated with phytoplanktonic biomass. At an hourly time scale, total bacterial biomass responded very rapidly to chlorophyll a fluctuations, suggesting a tight coupling between phytoplankton and bacteria for resource partitioning during the summer-autumn transition. In contrast, no influence of diel changes on bacterial parameters was detected. Episodic events such as coastal water intrusions had a significant positive effect on total bacterial abundance and production, whereas we could not detect any influence of short wind events whatever the magnitude. Finally, we show that particle-attached bacteria can represent a large proportion (up to 49%) of the total bacterial activity in the euphotic layer but display rapid and sporadic changes at hourly time scales. In the mesopelagic layers, bacterial abundance and production linearly decreased with depth, except some production peaks at 400–750 m. This study underlines the value of large datasets covering different temporal scales to clarify the biogeochemical role of bacteria in the cycling of organic matter in open seawater.

scholarly journals Bottom up effects on bacterioplankton growth and composition during summer-autumn transition in the open NW Mediterranean Sea

2009 ◽  
Vol 6 (4) ◽  
pp. 705-720 ◽  
Author(s):  
F. Van Wambeke ◽  
J.-F. Ghiglione ◽  
J. Nedoma ◽  
G. Mével ◽  
P. Raimbault
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Mediterranean Sea ◽  
Mixed Layer ◽  
Bacterial Production ◽  
Bacterial Community Structure ◽  
Bottom Up ◽  
Production Values ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. We examined the vertical and temporal dynamics of nutrients, ectoenzymatic activities under late summer-fall transition period (September–October 2004) in NW Mediterranean Sea in relation to temporal change in factors limiting bacterial production. The depth of the mixed layer (12.8±5.3 m) was extremely stable until the onset of the destratification period after 11 October, creating a zone where diffusion of nutrient from the much deeper phosphacline (69±12 m) and nitracline (50±8 m) was probably strongly limited. However after 1st October, a shallowing of nutriclines occured, particularly marked for nitracline. Hence, the nitrate to phosphate ratio within the mixed layer, although submitted to a high short term variability, shifted the last week of the cruise from 1.1±1.2 to 4.6±3.8, and nitrate increased by a factor 2 (0.092±0.049 μM). A corresponding switch from more than one limitation (PN) to P-only limitation of bacterial production was observed during the month as detected by enrichment bioassays. Differences in the identity of the limiting nutrient in surface (5 m: N and P at the beginning, strictly P at the end of the study) versus 80 m (labile carbon) influence greatly bacterial community structure shift between these two layers. The two communities (5 and 80 m) reacted rapidly (24 h) to changes in nutrient concentrations by drastic modification of total and active population assemblages resulting in changes in activity. For bacterial production values less than 10 ng C l−1 h−1 (associated to deeper layers), aminopeptidase and lipase exhibited higher activity relative to production whereas phosphatase varied in the same proportions than BP on the range of activities tested. Our results illustrate the effect of bottom-up control on bacterial community structure and activities in the epipelagic NW Mediterranean Sea.

Main drivers of spatial change in the biomass of commercial species between summer and winter in the NW Mediterranean Sea

2020 ◽  
pp. 105227
Author(s):  
Elena Lloret-Lloret ◽  
Maria Grazia Pennino ◽  
Daniel Vilas ◽  
José María Bellido ◽  
Joan Navarro ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Spatial Change ◽  
Commercial Species ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

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.

Sign in / Sign up

Export Citation Format

Share Document