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 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.

29 North-East Atlantic and the North Sea

2015 ◽  
Author(s):  
Long Ronán
Keyword(s):  
North Sea ◽  
Law Of The Sea ◽  
East Atlantic ◽  
Political Factors ◽  
Basic Principles ◽  
North East ◽  
The North ◽  
The North Sea ◽  
The Law ◽  
The Uk

This chapter assesses the legal regime of the North-East Atlantic and the North Sea. It begins by discussing some of the geographical, economic, environmental, strategic, and geo-political factors that are shaping the very distinctive regional regimes that give effect to the basic principles, as well as to many of the substantive provisions embodied in the UN Nations Convention on the Law of the Sea (LOSC) and related agreements. It provides a summary of the various maritime jurisdictional zones and boundaries claimed by the twelve coastal States that make-up the region: Belgium, Denmark, France, Germany, Iceland, Ireland, the Netherlands, Norway, Portugal, Spain, Sweden, and the UK. This is followed by a description of some of the principal regional bodies responsible for formulating and implementing various aspects of the law of the sea, including the regional seas environmental body, the EU and several fisheries management organizations.

scholarly journals Distribution of calcifying and silicifying phytoplankton in relation to environmental and biogeochemical parameters during the late stages of the 2005 North East Atlantic Spring Bloom

2009 ◽  
Vol 6 (10) ◽  
pp. 2155-2179 ◽  
Author(s):  
K. Leblanc ◽  
C. E. Hare ◽  
Y. Feng ◽  
G. M. Berg ◽  
G. R. DiTullio ◽  
...  
Keyword(s):  
Surface Layer ◽  
Biogenic Silica ◽  
Spring Bloom ◽  
Diatom Bloom ◽  
East Atlantic ◽  
Nitrogen And Phosphorus ◽  
North East ◽  
The North ◽  
Biogeochemical Parameters ◽  
Late Stages

Abstract. The late stage of the North East Atlantic (NEA) spring bloom was investigated during June 2005 along a transect section from 45 to 66° N between 15 and 20° W in order to characterize the contribution of siliceous and calcareous phytoplankton groups and describe their distribution in relation to environmental factors. We measured several biogeochemical parameters such as nutrients, surface trace metals, algal pigments, biogenic silica (BSi), particulate inorganic carbon (PIC) or calcium carbonate, particulate organic carbon, nitrogen and phosphorus (POC, PON and POP, respectively), as well as transparent exopolymer particles (TEP). Results were compared with other studies undertaken in this area since the JGOFS NABE program. Characteristics of the spring bloom generally agreed well with the accepted scenario for the development of the autotrophic community. The NEA seasonal diatom bloom was in the late stages when we sampled the area and diatoms were constrained to the northern part of our transect, over the Icelandic Basin (IB) and Icelandic Shelf (IS). Coccolithophores dominated the phytoplankton community, with a large distribution over the Rockall-Hatton Plateau (RHP) and IB. The Porcupine Abyssal Plain (PAP) region at the southern end of our transect was the region with the lowest biomass, as demonstrated by very low Chla concentrations and a community dominated by picophytoplankton. Early depletion of dissolved silicic acid (DSi) and increased stratification of the surface layer most likely triggered the end of the diatom bloom, leading to coccolithophore dominance. The chronic Si deficiency observed in the NEA could be linked to moderate Fe limitation, which increases the efficiency of the Si pump. TEP closely mirrored the distribution of both biogenic silica at depth and prymnesiophytes in the surface layer suggesting the sedimentation of the diatom bloom in the form of aggregates, but the relative contribution of diatoms and coccolithophores to carbon export in this area still needs to be resolved.

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.

The distribution of Ceratothoa steindachneri (Crustacea: Isopoda: Cymothoidae) parasitic in Echiichthys vipera in the north-east Atlantic

2002 ◽  
Vol 82 (3) ◽  
pp. 415-417 ◽  
Author(s):  
Tammy Horton ◽  
Beth Okamura
Keyword(s):  
Climate Change ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
South West ◽  
South West Coast ◽  
The 1960S ◽  
The Uk ◽  
Fish Hosts ◽  
Parasitic Isopod

The distribution of the recently discovered association of the parasitic isopod Ceratothoa steindachneri (Isopoda: Cymothoidae) with the lesser weever fish (Echiichthys vipera) is reported. Ceratothoa steindachneri appears to have colonized the south-west coast of the UK between the 1960s and the 1980s, possibly as a result of range expansion due to climate change. The occurrence of C. steindachneri in E. vipera from Arcachon, France, indicates that this association has been occurring for over 100 years. Our data confirm that C. steindachneri is able to parasitize a broad range of fish hosts.

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 Strandings of northern bottlenose whales, Hyperoodon ampullatus, in the north-east Atlantic: seasonality and diet

2014 ◽  
Vol 94 (6) ◽  
pp. 1109-1116 ◽  
Author(s):  
Ruth Fernández ◽  
Graham J. Pierce ◽  
Colin D. MacLeod ◽  
Andrew Brownlow ◽  
Robert J. Reid ◽  
...  
Keyword(s):  
The Netherlands ◽  
Stomach Contents ◽  
East Atlantic ◽  
North East ◽  
Deep Diving ◽  
The North ◽  
Coastal Species ◽  
Northern Bottlenose Whales ◽  
The Uk ◽  
Hyperoodon Ampullatus

Peaks in northern bottlenose whale, Hyperoodon ampullatus, strandings are found between August and September in the UK and August and November in The Netherlands, consistent with a hypothesized southward migration. However, results on diet suggest that several whales stranded during these months were not travelling from northern latitudes prior to stranding. We analysed the stomach contents of ten whales stranded in the north-east Atlantic (Scotland, N = 6, England, N = 1, Ireland, N = 2 and The Netherlands, N = 1). All but one of the analysed whales (live-stranded in the River Thames in January 2006) stranded between August and October. Food remains consisted almost entirely of cephalopod mandibles. Twenty-one cephalopod species (16 families) were recorded, the most abundant taxa being Gonatus spp., Teuthowenia spp. and Taonius pavo. No fish and few crustacean remains were found. Small amounts of cephalopod flesh were found in three of the stomachs and none in the others. Given that cephalopod beaks can remain within the stomach for several days, and that there was no evidence of inshore feeding (no coastal species were present among the prey), the whales may not have fed for several days prior to stranding. Three whales had remains of warm-temperate water cephalopods (e.g. Vampyroteuthis infernalis, Heteroteuthis sp.) in their stomachs, while three individuals showed a high diversity of prey in their stomachs, suggesting that several of the whales could have been either travelling north or consistently feeding in temperate latitudes prior to stranding. As previously recorded in other deep diving teuthophagous cetaceans, two animals had ingested small amounts of plastic debris.

Redescription and postmarsupial development of Apseudopsis latreillii (Crustacea: Tanaidacea)

2012 ◽  
Vol 92 (5) ◽  
pp. 1023-1041 ◽  
Author(s):  
P. Esquete ◽  
R.N. Bamber ◽  
J. Moreira ◽  
J.S. Troncoso
Keyword(s):  
Developmental Stage ◽  
Intraspecific Variation ◽  
Developmental Stages ◽  
East Atlantic ◽  
Diagnostic Characters ◽  
North East ◽  
The North ◽  
Preparatory Stage ◽  
Juvenile Stages ◽  
Pass Through

Apseudopsis latreillii is a common tanaidacean species widely-distributed in the north-east Atlantic, but its diagnostic characters remain unspecified. Furthermore, intraspecific variation in relation to its developmental stages has not been described. Knowledge about this variation is needed owing to the difficulty of identification of the significant number of juvenile specimens within samples, particularly when sympatric with other apseudid species. Specimens from three different localities of the north-east Atlantic have been examined, and the size of 766 individuals has been measured. Study of postmarsupial development shows that the manca II is followed by two juvenile stages before reaching maturity. Males present two possible morphologies. After a preparatory stage, females pass through a sequence of copulatory instars followed by intermediate stages in which the female loses the ovisac after manca release. Characters allowing the distinction of A. latreillii specimens regardless of developmental stage are the combination of a pointed and downturned rostrum, pereonites without apophyses, three ventral spines on the pereopod 1 propodus, and one dorsodistal spine on the merus.

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