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Onset of the spring bloom in the northwestern Mediterranean Sea: influence of environmental pulse events on the in situ hourly-scale dynamics of the phytoplankton community structure.

Thyssen M, Grégori GJ, Grisoni JM, Pedrotti ML, Mousseau L, Artigas LF, Marro S, Garcia N, Passafiume O, Denis MJ - Front Microbiol (2014)

Bottom Line: The third abundance pulse could be considered as the spring bloom commonly observed in the area.The high frequency data-set made it possible to study the phytoplankton cell cycle based on daily cycles of forward scatter and abundance.The combination of daily cell cycle, abundance trends and environmental pulses will open the way to the study of phytoplankton short-term reactivity to environmental conditions.

View Article: PubMed Central - PubMed

Affiliation: CNRS/INSU, IRD, Mediterranean Institute of Oceanography, Aix Marseille Université Marseille, France.

ABSTRACT
Most of phytoplankton influence is barely understood at the sub meso scale and daily scale because of the lack of means to simultaneously assess phytoplankton functionality, dynamics and community structure. For a few years now, it has been possible to address this objective with an automated in situ high frequency sampling strategy. In order to study the influence of environmental short-term events (nutrients, wind speed, precipitation, solar radiation, temperature, and salinity) on the onset of the phytoplankton bloom in the oligotrophic Bay of Villefranche-sur-Mer (NW Mediterranean Sea), a fully remotely controlled automated flow cytometer (CytoSense) was deployed on a solar-powered platform (EOL buoy, CNRS-Mobilis). The CytoSense carried out single-cell analyses on particles (1-800 μm in width, up to several mm in length), recording optical pulse shapes when analyzing several cm(3). Samples were taken every 2 h in the surface waters during 2 months. Up to 6 phytoplankton clusters were resolved based on their optical properties (PicoFLO, Picoeukaryotes, Nanophytoplankton, Microphytoplankton, HighSWS, HighFLO). Three main abundance pulses involving the 6 phytoplankton groups monitored indicated that the spring bloom not only depends on light and water column stability, but also on short-term events such as wind events and precipitation followed by nutrient pulses. Wind and precipitation were also determinant in the collapse of the clusters' abundances. These events occurred within a couple of days, and phytoplankton abundance reacted within days. The third abundance pulse could be considered as the spring bloom commonly observed in the area. The high frequency data-set made it possible to study the phytoplankton cell cycle based on daily cycles of forward scatter and abundance. The combination of daily cell cycle, abundance trends and environmental pulses will open the way to the study of phytoplankton short-term reactivity to environmental conditions.

No MeSH data available.


Related in: MedlinePlus

Periodic variations of abundances and average Total FWS signals per cell for each cluster resolved with the CytoSense (except PicoFLO) during the first marked abundance pulse (February 15–22). The corresponding hourly box plots are displayed in parallel. Note the differences between a low span (gray line: span2) and a high span (red line: span1) loess procedure for both variables. Abundance (103 cells.cm−3) and difference between span1 and span2: (A) picoeukaryotes. (B) HighSWS. (C) HighFLO. (D) nanophytoplankton. (E) microphytoplankton. Average cell Total FWS (a.u.) and difference between span1 and span2: (F) picoeukaryotes. (G) HighSWS. (H) HighFLO. (I) nanophytoplankton. (J) microphytoplankton. a.u., arbitrary unit.
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Figure 8: Periodic variations of abundances and average Total FWS signals per cell for each cluster resolved with the CytoSense (except PicoFLO) during the first marked abundance pulse (February 15–22). The corresponding hourly box plots are displayed in parallel. Note the differences between a low span (gray line: span2) and a high span (red line: span1) loess procedure for both variables. Abundance (103 cells.cm−3) and difference between span1 and span2: (A) picoeukaryotes. (B) HighSWS. (C) HighFLO. (D) nanophytoplankton. (E) microphytoplankton. Average cell Total FWS (a.u.) and difference between span1 and span2: (F) picoeukaryotes. (G) HighSWS. (H) HighFLO. (I) nanophytoplankton. (J) microphytoplankton. a.u., arbitrary unit.

Mentions: When analysing phytoplankton at the hourly scale by flow cytometry, it is possible to detect in situ diel cycles. Applying different loess spans is a way to separate the daily periodic information from the longer-term trend (Figures 8, 9). For each cluster, the daily variations in cell abundance and cell average FWS were plotted throughout abundance pulses for which the data-sets were almost complete, i.e. the first and third pulses [February 15–23 (Figure 8) and March 9–13 (Figure 9) respectively]. The diel variations of PicoFLO abundance are not reported here because of the large discrepancy between the values generated by the CytoSense and the FACSCalibur instruments. The CytoSense's under-sampling, although it affected the absolute values only and not the abundance trend, could have seriously distorted the average FWS and FLR intensities of this cluster.


Onset of the spring bloom in the northwestern Mediterranean Sea: influence of environmental pulse events on the in situ hourly-scale dynamics of the phytoplankton community structure.

Thyssen M, Grégori GJ, Grisoni JM, Pedrotti ML, Mousseau L, Artigas LF, Marro S, Garcia N, Passafiume O, Denis MJ - Front Microbiol (2014)

Periodic variations of abundances and average Total FWS signals per cell for each cluster resolved with the CytoSense (except PicoFLO) during the first marked abundance pulse (February 15–22). The corresponding hourly box plots are displayed in parallel. Note the differences between a low span (gray line: span2) and a high span (red line: span1) loess procedure for both variables. Abundance (103 cells.cm−3) and difference between span1 and span2: (A) picoeukaryotes. (B) HighSWS. (C) HighFLO. (D) nanophytoplankton. (E) microphytoplankton. Average cell Total FWS (a.u.) and difference between span1 and span2: (F) picoeukaryotes. (G) HighSWS. (H) HighFLO. (I) nanophytoplankton. (J) microphytoplankton. a.u., arbitrary unit.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4129916&req=5

Figure 8: Periodic variations of abundances and average Total FWS signals per cell for each cluster resolved with the CytoSense (except PicoFLO) during the first marked abundance pulse (February 15–22). The corresponding hourly box plots are displayed in parallel. Note the differences between a low span (gray line: span2) and a high span (red line: span1) loess procedure for both variables. Abundance (103 cells.cm−3) and difference between span1 and span2: (A) picoeukaryotes. (B) HighSWS. (C) HighFLO. (D) nanophytoplankton. (E) microphytoplankton. Average cell Total FWS (a.u.) and difference between span1 and span2: (F) picoeukaryotes. (G) HighSWS. (H) HighFLO. (I) nanophytoplankton. (J) microphytoplankton. a.u., arbitrary unit.
Mentions: When analysing phytoplankton at the hourly scale by flow cytometry, it is possible to detect in situ diel cycles. Applying different loess spans is a way to separate the daily periodic information from the longer-term trend (Figures 8, 9). For each cluster, the daily variations in cell abundance and cell average FWS were plotted throughout abundance pulses for which the data-sets were almost complete, i.e. the first and third pulses [February 15–23 (Figure 8) and March 9–13 (Figure 9) respectively]. The diel variations of PicoFLO abundance are not reported here because of the large discrepancy between the values generated by the CytoSense and the FACSCalibur instruments. The CytoSense's under-sampling, although it affected the absolute values only and not the abundance trend, could have seriously distorted the average FWS and FLR intensities of this cluster.

Bottom Line: The third abundance pulse could be considered as the spring bloom commonly observed in the area.The high frequency data-set made it possible to study the phytoplankton cell cycle based on daily cycles of forward scatter and abundance.The combination of daily cell cycle, abundance trends and environmental pulses will open the way to the study of phytoplankton short-term reactivity to environmental conditions.

View Article: PubMed Central - PubMed

Affiliation: CNRS/INSU, IRD, Mediterranean Institute of Oceanography, Aix Marseille Université Marseille, France.

ABSTRACT
Most of phytoplankton influence is barely understood at the sub meso scale and daily scale because of the lack of means to simultaneously assess phytoplankton functionality, dynamics and community structure. For a few years now, it has been possible to address this objective with an automated in situ high frequency sampling strategy. In order to study the influence of environmental short-term events (nutrients, wind speed, precipitation, solar radiation, temperature, and salinity) on the onset of the phytoplankton bloom in the oligotrophic Bay of Villefranche-sur-Mer (NW Mediterranean Sea), a fully remotely controlled automated flow cytometer (CytoSense) was deployed on a solar-powered platform (EOL buoy, CNRS-Mobilis). The CytoSense carried out single-cell analyses on particles (1-800 μm in width, up to several mm in length), recording optical pulse shapes when analyzing several cm(3). Samples were taken every 2 h in the surface waters during 2 months. Up to 6 phytoplankton clusters were resolved based on their optical properties (PicoFLO, Picoeukaryotes, Nanophytoplankton, Microphytoplankton, HighSWS, HighFLO). Three main abundance pulses involving the 6 phytoplankton groups monitored indicated that the spring bloom not only depends on light and water column stability, but also on short-term events such as wind events and precipitation followed by nutrient pulses. Wind and precipitation were also determinant in the collapse of the clusters' abundances. These events occurred within a couple of days, and phytoplankton abundance reacted within days. The third abundance pulse could be considered as the spring bloom commonly observed in the area. The high frequency data-set made it possible to study the phytoplankton cell cycle based on daily cycles of forward scatter and abundance. The combination of daily cell cycle, abundance trends and environmental pulses will open the way to the study of phytoplankton short-term reactivity to environmental conditions.

No MeSH data available.


Related in: MedlinePlus