scholarly journals Sub meso scale phytoplankton distribution in the North East Atlantic surface waters determined with an automated flow cytometer

2009 ◽  
Vol 6 (4) ◽  
pp. 569-583 ◽  
Author(s):  
M. Thyssen ◽  
N. Garcia ◽  
M. Denis
Keyword(s):  
Surface Waters ◽  
High Frequency ◽  
Mixed Layer Depth ◽  
Nutrient Concentrations ◽  
Layer Depth ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Phytoplankton Distribution ◽  
Meso Scale

Abstract. Phytoplankton cells in the size range ~1–50 μm were analysed in surface waters using an automated flow cytometer, the Cytosub (http://www.cytobuoy.com), from the Azores to the French Brittany during spring 2007. The Cytosub records the pulse shape of the optical signals generated by phytoplankton cells when intercepted by the laser beam. A total of 6 distinct optical groups were resolved during the whole transect, and the high frequency sampling (15 min) provided evidence for the cellular cycle (based on cyclic changes in cell size and fluorescence) and distribution changes linked to the different water characteristics crossed in the North East Atlantic provinces. Nutrient concentrations and mixed layer depth varied from west to east, with a decrease in the mixed layer depth and high nutrient concentrations in the middle of the transect as well as near the French coast. Data provided a link between the sub meso scale processes and phytoplankton patchiness, some abundance variations due to the cellular cycle can be pointed out. The high frequency spatial sampling encompasses temporal variations of the phytoplankton abundance, offering a better insight into phytoplankton distribution.

scholarly journals Sub meso scale phytoplankton distribution in the north east Atlantic surface waters determined with an automated flow cytometer

2008 ◽  
Vol 5 (3) ◽  
pp. 2471-2503
Author(s):  
M. Thyssen ◽  
N. Garcia ◽  
M. Denis
Keyword(s):  
Surface Waters ◽  
High Frequency ◽  
Mixed Layer Depth ◽  
Nutrient Concentrations ◽  
Layer Depth ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Phytoplankton Distribution ◽  
Meso Scale

Abstract. Phytoplankton cells in the size range ~1–50 μm were analysed in surface waters using an automated flow cytometer, the Cytosub (http://www.cytobuoy.com), from the Azores to the French Brittany during spring 2007. The Cytosub records the pulse shape of the optical signals generated by phytoplankton cells when intercepted by the laser beam. A total of 6 distinct optical groups were resolved during the whole transect, and the high frequency sampling (15 min) provided evidence for the cellular cycle (based on cyclic changes in cell size and fluorescence) and distribution changes linked to the different water characteristics crossed in the north east Atlantic provinces. Nutrient concentrations and mixed layer depth varied from west to east, with a decrease in the mixed layer depth and high nutrient concentrations in the middle of the transect as well as near the French coast. Data provided a link between the sub meso scale processes and phytoplankton patchiness, some abundance variations due to the cellular cycle can be pointed out. The high frequency spatial sampling encompasses temporal variations of the phytoplankton abundance, offering a better insight into phytoplankton distribution.

scholarly journals Forecasting the mixed layer depth in the north east Atlantic: an ensemble approach, with uncertainties based on data from operational oceanic systems

2014 ◽  
Vol 11 (3) ◽  
pp. 1435-1472
Author(s):  
Y. Drillet ◽  
J. M. Lellouche ◽  
B. Levier ◽  
M. Drévillon ◽  
O. Le Galloudec ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Forecast Error ◽  
Mixed Layer Depth ◽  
Layer Depth ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Uncertainty Estimates ◽  
Operational Systems ◽  
The Impact

Abstract. Operational systems operated by Mercator Océan provide daily ocean forecasts, and combining these forecasts we can produce ensemble forecast and uncertainty estimates. This study focuses on the mixed layer depth in the North East Atlantic near the Porcupine Abyssal Plain for May 2013. This period is of interest for several reasons: (1) four Mercator Océan operational systems provide daily forecasts at a horizontal resolution of 1/4°, 1/12° and 1/36° with different physics; (2) glider deployment under the OSMOSIS project provides observation of the changes in mixed layer depth; (3) the ocean stratifies in May, but mixing events induced by gale force wind are observed and forecasted by the systems. A statistical approach and forecast error quantification for each system and for the combined products are presented. Skill scores indicate that forecasts are in any case better than persistence, and temporal correlations between forecast and observations are greater than 0.8 even for the 4 day forecast. The impact of atmospheric forecast error, and for the wind field in particular, is also quantified in terms of the forecast time delay and the intensity of mixing or stratification events.

Microzooplankton dynamics during the development of the spring bloom in the north-east Atlantic

2005 ◽  
Vol 85 (4) ◽  
pp. 741-753 ◽  
Author(s):  
E.S. Fileman ◽  
R.J.G. Leakey
Keyword(s):  
Developmental Stages ◽  
Spring Bloom ◽  
Mixed Layer Depth ◽  
Grazing Impact ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Protozoan Community ◽  
Community Growth ◽  
The Uk

Microzooplankton community composition, abundance, biomass and grazing impact were assessed, along with measurements of ciliate growth and mortality, during the onset of the spring bloom in the north-east Atlantic. The study was undertaken as part of the UK Biogeochemical Ocean Flux Study during 1 May to 15 June 1990. The microzooplankton community was composed of protozoans and metazoan developmental stages with respective mixed-layer depth integrated biomass values ranging from 127 to 638 and 74 to 394 mg C m−2. High numbers of aloricate ciliates (up to 35,000 cells l−1) dominated the microzooplankton community during early May prior to the onset of the spring bloom. Ciliate abundance then declined rapidly during mid-May with community growth rates ranging from −0·71 to 0·23 d−1. High abundances of metazoplankton (up to 400 l−1) were also recorded at this time and may have contributed to the decline in ciliate numbers. In late May and early June the protozoan community comprised a more even mix of dinoflagellates, tintinnids and aloricate ciliates. Phytoplankton mortality rates, measured using a dilution technique, ranged from 0·2 to 0·5 d−1. The microzooplankton consumed 8 to 44 μg C l−1 d−1, equivalent to between 16 and 40% of the chlorophyll biomass and 38 and 154% of primary production. These high rates of herbivory reflect the predominance of small (<5 μm in length) phytoplankton cells present throughout the first half of the study and support previous studies demonstrating the microzooplankton to be the main grazers of phytoplankton in the north-east Atlantic. However, there is also evidence that a disparity between predator and prey may have prevented a response by the microzooplankton to rapid increases in phytoplankton biomass and production during the spring bloom.

scholarly journals Interannual stability of phytoplankton community composition in the North-East Atlantic

2020 ◽  
Vol 655 ◽  
pp. 43-57
Author(s):  
S Allen ◽  
S Henson ◽  
A Hickman ◽  
C Beaulieu ◽  
PC Doncaster ◽  
...  
Keyword(s):  
Community Structure ◽  
Community Composition ◽  
Phytoplankton Community ◽  
Decadal Variability ◽  
Mixed Layer Depth ◽  
Phytoplankton Community Structure ◽  
East Atlantic ◽  
Phytoplankton Community Composition ◽  
North East ◽  
The North

As primary producers, phytoplankton play a pivotal role in the marine environment and are central to many biogeochemical processes. Changes to phytoplankton community composition could have major consequences for wider ecosystem functioning and may occur in response to climate change. Here we describe multi-decadal variability in phytoplankton community structure using taxonomic data from the Continuous Plankton Recorder collected in the North-East Atlantic from 1969-2013, using a total of 42 diatom and dinoflagellate taxa. We considered a range of characteristics of community structure, including taxonomic diversity and community stability and disorder, and how these characteristics change in response to sea surface temperature, mixed layer depth and the North Atlantic Oscillation. We found that phytoplankton community composition was largely stable on interannual timescales. A change in community composition occurred between 1985 and 1995 due to an increased dominance of 2 diatom taxa (Rhizosolenia styliformis and Thalassiosira spp.); however, after this period, the community returned to its previous composition. Further, a community disorder analysis found that phytoplankton compositional structure became more rigid in recent years, which may lead to an eventual community shift in the future. In contrast to previous studies that revealed relationships between total phytoplankton abundance or biomass and environmental forcing, we found that community structure had, at most, a very weak relationship with the environmental parameters tested. Changes to the physical environment may therefore have less influence at interannual timescales on phytoplankton community structure than previously thought.

scholarly journals Thrust–wrench interference tectonics in the Gulf of Cadiz (Africa–Iberia plate boundary in the North-East Atlantic): Insights from analog models

2011 ◽  
Vol 289 (1-4) ◽  
pp. 135-149 ◽  
Author(s):  
João C. Duarte ◽  
Filipe M. Rosas ◽  
Pedro Terrinha ◽  
Marc-André Gutscher ◽  
Jacques Malavieille ◽  
...  
Keyword(s):  
Plate Boundary ◽  
Gulf Of Cadiz ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Gulf Of Cádiz ◽  
Analog Models

Exceptional influx of oceanic species into the North Sea late 1997

1999 ◽  
Vol 79 (4) ◽  
pp. 737-739 ◽  
Author(s):  
M. Edwards ◽  
A.W.G. John ◽  
H.G. Hunt ◽  
J.A. Lindley
Keyword(s):  
North Sea ◽  
Indicator Species ◽  
Climatic Conditions ◽  
Historical Evidence ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
The North Sea ◽  
Oceanic Species

Continuous Plankton Recorder records from the North Sea and north-east Atlantic from September 1997 to March 1998 indicate an exceptional influx of oceanic indicator species into the North Sea. These inflow events, according to historical evidence, have only occurred sporadically during this century. This exceptional inflow and previous inflow events are discussed in relation to their similarity in terms of their physical and climatic conditions.

Artificial reefs in the North –East Atlantic area: Present situation, knowledge gaps and future perspectives

2021 ◽  
Vol 213 ◽  
pp. 105854
Author(s):  
Bianca Reis ◽  
Pieter van der Linden ◽  
Isabel Sousa Pinto ◽  
Emanuel Almada ◽  
Maria Teresa Borges ◽  
...  
Keyword(s):  
Present Situation ◽  
Artificial Reefs ◽  
Future Perspectives ◽  
East Atlantic ◽  
Knowledge Gaps ◽  
North East ◽  
The North ◽  
Atlantic Area
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