Isolation of viruses responsible for the demise of an Emiliania huxleyi bloom in the English Channel

This study used analytical flow cytometry (AFC) to monitor the abundance of phytoplankton, coccoliths, bacteria and viruses in a transect that crossed a high reflectance area in the western English Channel. The high reflectance area, observed by satellite, was caused by the demise of an Emiliania huxleyi bloom. Water samples were collected from depth profiles at four stations, one station outside and three stations inside the high reflectance area. Plots of transect data revealed very obvious differences between Station 1, outside, and Stations 2–4, inside the high reflectance area. Inside, concentrations of viruses were higher; E. huxleyi cells were lower; coccoliths were higher; bacteria were higher and virus:bacteria ratio was lower than at Station 1, outside the high reflectance area. This data can simply be interpreted as virus-induced lysis of E. huxleyi cells in the bloom causing large concentrations of coccoliths to detach, resulting in the high reflectance observed by satellite imagery. This interpretation was supported by the isolation of two viruses, EhV84 and EhV86, from the high reflectance area that lysed cultures of E. huxleyi host strain CCMP1516. Basic characterization revealed that they were lytic viruses approximately 170 nm–190 nm in diameter with an icosahedral symmetry. Taken together, transect and isolation data suggest that viruses were the major contributor to the demise of the E. huxleyi population in the high reflectance area. Close coupling between microalgae, bacteria and viruses contributed to a large organic carbon input. Consequent cycling influenced the succession of an E. huxleyi-dominated population to a more characteristic mixed summer phytoplankton community.

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Microplankton community structure and the impact of microzooplankton grazing during an Emiliania huxleyi bloom, off the Devon coast

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315402005593 ◽

2002 ◽

Vol 82 (3) ◽

pp. 359-368 ◽

Cited By ~ 29

Author(s):

E.S. Fileman ◽

D.G. Cummings ◽

C.A. Llewellyn

Keyword(s):

Community Structure ◽

Phytoplankton Community ◽

Emiliania Huxleyi ◽

Pigment Analysis ◽

Protozoan Community ◽

Grazing Mortality ◽

Standing Stocks ◽

The Impact ◽

Microzooplankton Grazing ◽

High Reflectance

Phytoplankton and microzooplankton community structure and the impact of microzooplankton grazing were investigated during a one-day study of an Emiliania huxleyi bloom off the coast of Devon during July 1999. Vertical profiles were undertaken at four stations, along a transect which crossed from a low reflectance to a high reflectance area as seen by satellite imagery. Microzooplankton dilution grazing experiments, coupled with pigment analysis to determine class specific grazing rates, were performed at two of these stations.Highest concentrations of chlorophyll-a (5·3 mg m−3) and accessory pigments were measured inside the area of high reflectance. Phytoplankton standing stocks ranged between 1588 and 5460 mg C m−2 and were also highest in the area of high reflectance. The phytoplankton community was dominated by coccolithophores and diatoms in low reflectance waters and by photosynthetic dinoflagellates in high reflectance areas. Microzooplankton standing stocks ranged between 905 and 2498 mg C m−2. Protozoa dominated the microzooplankton community. The protozoan community comprised a relatively even mixture of heterotrophic dinoflagellates, non-choreotrich and choreotrich ciliates in low reflectance waters. However, non-choreotrich ciliates dominated the communities inside the high reflectance area. Of the heterotrophic ciliates, a predatory ciliate Askenasia sp. dominated both non-choreotrich abundance and biomass.Results from grazing experiments showed that 60–64% of the chlorophyll-a biomass was consumed daily by the microzooplankton. Highest grazing mortality was associated with peridinin (dinoflagellates) and alloxanthin (cryptophytes). Lower grazing rates were found on fucoxanthin (diatoms and prymnesiophytes). Our results indicate that grazing on E. huxleyi in the area of remotely sensed high reflectance was low and highest grazing was on photosynthetic dinoflagellates and cryptophytes.

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Supplementary material to "Effects of elevated CO<sub>2</sub> and temperature on phytoplankton community biomass, species composition and photosynthesis during an autumn bloom in the Western English Channel"

10.5194/bg-2017-510-supplement ◽

2017 ◽

Author(s):

Matthew Keys ◽

Gavin Tilstone ◽

Helen S. Findlay ◽

Claire E. Widdicombe ◽

Tracy Lawson

Keyword(s):

Species Composition ◽

Phytoplankton Community ◽

English Channel ◽

Community Biomass ◽

Supplementary Material

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Phytoplankton community during a coccolithophorid bloom in the Patagonian Shelf: microscopic and high-performance liquid chromatography pigment analyses

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315411000439 ◽

2011 ◽

Vol 92 (1) ◽

pp. 13-27 ◽

Cited By ~ 15

Author(s):

Márcio Silva de Souza ◽

Carlos Rafael Borges Mendes ◽

Virgínia Maria Tavano Garcia ◽

Ricardo Pollery ◽

Vanda Brotas

Keyword(s):

High Performance Liquid Chromatography ◽

Liquid Chromatography ◽

High Performance ◽

Phytoplankton Community ◽

Sampling Period ◽

Emiliania Huxleyi ◽

Patagonian Shelf ◽

Phaeocystis Antarctica ◽

Hplc Data ◽

Phytoplankton Group

We describe the phytoplankton community and biomass during a summer coccolithophorid bloom sampled over the Patagonian shelf (48.5°S–50.5°S). Those phytoplankton species can contribute to the flux of calcium carbonate out of surface waters. Results from both microscope and high-performance liquid chromatography (HPLC) analysis are shown to complement information on the phytoplankton community. From CHEMTAX analysis of HPLC data, the most important organisms and groups identified were the coccolithophorid Emiliania huxleyi, the haptophyte Phaeocystis antarctica, dinoflagellates, diatoms, cryptophytes, prasinophytes and cyanobacteria. Phytoplankton microscope counts were converted into phytoplankton group-specific biovolume estimates. Although some microscope-identified taxa could not be determined by CHEMTAX, e.g. the autotrophic ciliate Myrionecta rubra, cluster analyses from both techniques showed similar results for the main groups. Both Emiliania huxleyi cell concentration and biomass, and the pigment 19′-hexanoyloxyfucoxanthin were the most important biological features during the sampling period. At surface, nitrate was moderately high (0.2–4.2 µM) in coccolithophorid-dominated samples, whereas phosphate (<0.33 µM) and silicate (<1.35 µM) concentrations were low. Among the environmental factors low Si:N ratios were mainly associated with the dominance of E. huxleyi. Competition and probably differential grazing could also promote a coccolithophorid outgrowth over other photoautotrophs during the summer season in the Patagonian shelf.

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High spatial variability of phytoplankton assessed by flow cytometry, in a dynamic productive coastal area, in spring: The eastern English Channel

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2014.12.037 ◽

2015 ◽

Vol 154 ◽

pp. 214-223 ◽

Cited By ~ 13

Author(s):

Simon Bonato ◽

Urania Christaki ◽

Alain Lefebvre ◽

Fabrice Lizon ◽

Melilotus Thyssen ◽

...

Keyword(s):

Flow Cytometry ◽

Spatial Variability ◽

Coastal Area ◽

English Channel ◽

High Spatial Variability

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High-resolution analysis of a North Sea phytoplankton community structure based on in situ flow cytometry observations and potential implication for remote sensing

Biogeosciences ◽

10.5194/bg-12-4051-2015 ◽

2015 ◽

Vol 12 (13) ◽

pp. 4051-4066 ◽

Cited By ~ 22

Author(s):

M. Thyssen ◽

S. Alvain ◽

A. Lefèbvre ◽

D. Dessailly ◽

M. Rijkeboer ◽

...

Keyword(s):

Flow Cytometry ◽

Community Structure ◽

North Sea ◽

High Frequency ◽

Phytoplankton Community ◽

Phytoplankton Community Structure ◽

The North ◽

The North Sea ◽

Daily Scale

Abstract. Phytoplankton observation in the ocean can be a challenge in oceanography. Accurate estimations of its biomass and dynamics will help to understand ocean ecosystems and refine global climate models. Relevant data sets of phytoplankton defined at a functional level and on a sub-meso- and daily scale are thus required. In order to achieve this, an automated, high-frequency, dedicated scanning flow cytometer (SFC, Cytobuoy b.v., the Netherlands) has been developed to cover the entire size range of phytoplankton cells whilst simultaneously taking pictures of the largest of them. This cytometer was directly connected to the water inlet of a PocketFerryBox during a cruise in the North Sea, 08–12 May 2011 (DYMAPHY project, INTERREG IV A "2 Seas"), in order to identify the phytoplankton community structure of near surface waters (6 m) with a high spatial resolution basis (2.2 ± 1.8 km). Ten groups of cells, distinguished on the basis of their optical pulse shapes, were described (abundance, size estimate, red fluorescence per unit volume). Abundances varied depending on the hydrological status of the traversed waters, reflecting different stages of the North Sea blooming period. Comparisons between several techniques analysing chlorophyll a and the scanning flow cytometer, using the integrated red fluorescence emitted by each counted cell, showed significant correlations. For the first time, the community structure observed from the automated flow cytometry data set was compared with PHYSAT reflectance anomalies over a daily scale. The number of matchups observed between the SFC automated high-frequency in situ sampling and remote sensing was found to be more than 2 times better than when using traditional water sampling strategies. Significant differences in the phytoplankton community structure within the 2 days for which matchups were available suggest that it is possible to label PHYSAT anomalies using automated flow cytometry to resolve not only dominant groups but also community structure.

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