Coagulation Efficiency of Phytoplankton Cells During Different Growth Stages
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*Jenni Szlosek 1,2 , Anja Engel 2 , Cindy Lee 1 , Robert Armstrong 1 PowerPoint PPT Presentation


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Coagulation Efficiency of Phytoplankton Cells During Different Growth Stages and Its Relationship to Exopolymer Particle Properties. *Jenni Szlosek 1,2 , Anja Engel 2 , Cindy Lee 1 , Robert Armstrong 1 1 Marine Sciences Research Center, Stony Brook University, Stony Brook, NY USA

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Jenni szlosek 1 2 anja engel 2 cindy lee 1 robert armstrong 1

Coagulation Efficiency of Phytoplankton Cells During Different Growth Stages and Its Relationship to Exopolymer Particle Properties

*Jenni Szlosek1,2, Anja Engel2, Cindy Lee1, Robert Armstrong1

1Marine Sciences Research Center, Stony Brook University, Stony Brook, NY USA

2Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany

[email protected]


Introduction

  •  increases with drop in phytoplankton growth rate

  • Increase in TEP abundance leads to increased 

  • No indication that differences in dissolved polysaccharide composition with growth affects 

Introduction

  • Phytoplankton aggregation is an important mechanism for the export of organic carbon

  • Exopolymer particles such as TEP may play an important role in the coagulation efficiency of cells

  • The value of  used in aggregation calculations may not always represent the “real” value of the system.

    Goal:

    Understand the role exopolymerparticle abundance and exopolymer chemical composition plays in enhancing phytoplankton aggregation.

  • Approach:

  • Compare effect of TEP number vs. exopolymer chemical quality on 

  • Limit variability in  due to experimental set-up

  • Compare results for diatoms vs. coccolithophores


Coagulation efficiency

# of particles

Ci =

unit volume

slope=Q

after Kiørboe et al., 1990:

=Q

ln(∑C(t))

time sampled

Drapeau et al., 1994

  • Known:

  • Gm, mean shear

  • Constants describing physics: 7.82, π

photo of Couette flow device

schematic of Couette flow device

What affects

 …?

  • Uncertain:

  •  , volume fraction  TEP contribution

  • Chemical quality of exopolymers as cell coatings

  • and transparent particles

Coagulation Efficiency


Experimental set up

Experimental Set Up

Emiliania huxleyi grown as chemostat cultures

  • Grown at 15˚C in enriched media:

    50 µM N

    3 µM P

    f/2 trace metals and vitamins

  • Steady-state growth reached for turnover times of:

    0.48, 0.25, 0.1, 0.05 d-1

  • Cell exponential growth rates equaled turnover times


Coagulation efficiency1

Coagulation Efficiency

=Q

  • No indication of coagulation at highest growth rate (0.48 d-1)

  • The magnitude of the slope (Q) increases with decreasing exponential growth rate

  • Alpha increases with decreasing exponential growth rate

Alpha with Growth Stage

alpha

Exponential Growth Rate (d-1)


Tep abundance

TEP Abundance

E. hux TEP with Growth Stage

TEP conc. (µg Xanthan Gum L-1)

Exponential Growth Rate (d-1)

direction of “bloom” progression

Alpha with Growth Stage

  • Increase in TEP with decrease in growth stage

  • Correlation between TEP abundance and  yields an R2 of 0.85

alpha

Exponential Growth Rate (d-1)


Dissolved aldose composition

Dissolved Aldose Composition

  • Decrease in Mol% Glucose with decreasing exponential growth rate

  • Sugars found in coccoliths of E. huxleyi present in nearly constant amounts throughout growth stages

  • Effect of changes in dissolved sugar composition on  requires further work

Exponential Growth Rate (d-1)

Exponential Growth Rate (d-1)


Diatoms vs coccolithophores

Diatoms vs. Coccolithophores

Thalassiosira weissflogii (batch culture)

Emiliania huxleyi (chemostat culture)

TEP concentration(µg Xanthan Gum L-1)


Conclusions

Conclusions

  • Attachment probability,  , increases with decreasing exponential growth rate (progression of “bloom”)

  •  correlates with TEP abundance as expected

  • Possible importance of DOM chemical composition on attachment probability of cells is undetermined

  • Chemostat culturing is a useful technique to reduce the experimental variability of 


Acknowledgements

Acknowledgements

  • Nicole Händel, AWI

  • Umesh Gangeshetti, AWI

  • Stephanie Koch, AWI


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