Transcript Transparent exopolymer particles (TEP) under ocean

Transparent exopolymer
particles (TEP) under ocean
acidification conditions
Presented by Daneil Newcomb at Friday Harbor Labs for the Ocean
Acidification Apprenticeship
What is TEP?
• A carbohydrate rich polysaccharide form of organic matter
produced by phytoplankton and some bacteria
• Most likely produced as a response to cell stress (too little or
too much of a resource), not seen in actively growing cells
• Increased TEP production is correlated with the maintenance
and senescence phases of phytoplankton growth
• In previous ocean acidification studies:
– Bulk TEP has been correlated to chlorophyll-a, bacterial production,
dissolved organic matter, and particulate organic matter
• These correlations appear to be dependent on the presence of a phytoplankton
bloom.
• A possible mechanism to increase export of carbon from
surface waters to depth
(Wurl et al. 2011)
Phytoplankton exude
polysaccharides
(Wurl et al. 2011)
Phytoplankton exude
polysaccharides
TEP is formed through
aggregation
(Wurl et al. 2011)
Phytoplankton exude
polysaccharides
TEP is formed through
aggregation
marine snow
Aggregates
are removed
from system
via export
(Wurl et al. 2011)
Factors affecting TEP production and
cycling
• Abiotic
–
–
–
–
–
Temperature
Turbulence
pH
Nutrients
Sedimentation
• Biotic
– Phytoplankton and
bacterial production
– Bacterial
remineralization
– Viral lysis
– Grazing by zoo- and
microzooplankton
Factors affecting TEP production and
cycling
• Abiotic
–
–
–
–
–
Temperature
Turbulence
pH
Nutrients
Sedimentation
• Biotic
– Phytoplankton and
bacterial production
– Bacterial
remineralization
– Viral lysis
– Grazing by zoo- and
microzooplankton
Factors affecting TEP production and
cycling
• Abiotic
–
–
–
–
–
Temperature
Turbulence
pH
Nutrients
Sedimentation
• Biotic
– Phytoplankton and
bacterial production
– Bacterial
remineralization
– Viral lysis
– Grazing by zoo- and
microzooplankton
Factors affecting TEP production and
cycling
• Abiotic
–
–
–
–
–
Temperature
Turbulence
pH
Nutrients
Sedimentation
• Biotic
– Phytoplankton and
bacterial production
– Bacterial
remineralization
– Viral lysis
– Grazing by zoo- and
microzooplankton
Factors affecting TEP production and
cycling
• Abiotic
–
–
–
–
–
Temperature
Turbulence
pH
Nutrients
Sedimentation
• Biotic
– Phytoplankton and
bacterial production
– Bacterial
remineralization
– Viral lysis
– Grazing by zoo- and
microzooplankton
Factors affecting TEP production and
cycling
• Abiotic
–
–
–
–
–
Temperature
Turbulence
pH
Nutrients
Sedimentation
• Biotic
– Phytoplankton and
bacterial production
– Bacterial
remineralization
– Viral lysis
– Grazing by zoo- and
microzooplankton
Experimental Objectives
• Determine how chosen factors affect TEP
production within the mesocosm experiment
– To examine correlations between bulk TEP
production and phytoplankton, bacteria, and
microzooplankton.
– To determine any significant difference in TEP
production between in situ water conditions and
FHL and the acidified ocean of the future.
Materials and Methods
• Nine mesocosms, three
treatments
• Duplicate samples taken
with an integrated
sampler
• Samples filtered within
two hours of collection*
* Except made for fossil hunting
Materials and Methods
0.25
y = 0.0011x + 0.0253
R² = 0.921
• Analyzing TEP
• Absorbance is related to
weights using a
calibration curve
0.2
Absorption (E787 - C787)
– Filters are stained with
Alcian Blue, soaked in
80% sulfuric acid, then
analyzed using the
colorimetric method.
y = 0.0008x + 0.0575
R² = 0.6826
0.15
0.1
y = 0.0007x + 0.0201
R² = 0.5747
0.05
0
0
50
100
Gum Xanthan (mg)
150
200
TEP Mesocosm Time Series
900
HIGH
CONTROL
Median TEP (mg Gum Xanthan
L-1)
800
DRIFT
DOCK
700
600
500
400
300
200
100
0
0
2
4
6
8
10
12
Time (Days)
14
16
18
20
TEP Mesocosm Time Series
900
Median TEP (mg Gum Xanthan
L-1)
800
700
600
500
400
300
200
100
0
0
2
4
6
8
10
12
Time (Days)
14
16
18
20
TEP Mesocosm Time Series
900
Median TEP (mg Gum Xanthan
L-1)
800
Drift-High
0.848
p < 0.001
Control-High
0.030
p = 0.902
Drift-Control
0.879
p = 0.001
700
600
500
400
300
200
100
0
0
2
4
6
8
10
12
Time (Days)
14
16
18
20
TEP Mesocosm Time Series
900
Median TEP (mg Gum Xanthan
L-1)
800
Why are the high and control
different from the drift but not
each other?
700
600
500
400
300
200
100
0
0
2
4
6
8
10
12
Time (Days)
14
16
18
20
What makes the drift different?
– How are the biotic
factors, such as
phytoplankton and
bacteria, responding to
the treatments?
– How do the abiotic factor
differ between
treatments?
– Which of these abiotic
factors effect the
physiological response
of these organisms?
900
Median TEP (mg Gum Xanthan
L-1)
800
700
600
500
400
300
200
100
0
0
2
4
6
8
10
Time (Days)
12
14
16
18
20
40
Biotic Factor:
Phytoplankton
Median Chlorophyll (mg L-1)
35
30
25
20
15
10
5
0
T0
T2
T4
T6
T8
T10
T12
T14
T16
T18
T20
Time (Days)
900
Median TEP (mg Gum Xanthan L-1)
800
700
600
500
• Both Chlorophyll a and TEP
show the control ending above
the high, and increase over
time.
• For both the drift treatment is
significantly lower than the
high treatment.
• Suggest phytoplankton are the
main producers of TEP in the
system.
400
r
300
200
Control
0.837
100
High
0.851
Drift
0.794
0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
P < 0.001
Biotic Factor:
Bacteria
• The control and high
treatments are
significantly higher than
the drift treatment for
both Bacterial
Abundance and TEP.
900
Median TEP (mg Gum Xanthan L-1)
800
700
600
500
400
r
300
200
Control
0.882
100
High
0.754
Drift
0.388
0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
P < 0.03
But why is the drift significantly lower?
• All treatments experienced the same
temperature and turbulence conditions
• Initial nutrients were highly similar in all
treatments
• The only factor which changed between
treatments was the pCO2
– Drift was allowed to change whereas High and
Control concentrations were maintained
But why is the drift significantly lower?
DRIFT
But why is the drift significantly lower?
But why is the drift significantly lower?
But why is the drift significantly lower?
Photosynthesis: 106CO2 + 16NO3 + PO4  ORGANIC MATTER + 138O2
But why is the drift significantly lower?
HIGH OR
CONTROL
But why is the drift significantly lower?
But why is the drift significantly lower?
But why is the drift significantly lower?
Photosynthesis: 106CO2 + 16NO3 + PO4  ORGANIC MATTER + 138O2
But why is the drift significantly lower?
Photosynthesis: 106CO2 + 16NO3 + PO4  ORGANIC MATTER + 138O2
But why is the drift significantly lower?
Conclusions
• TEP production is affected by repetitive
enrichment of waters with CO2
• The ways different factors influence TEP
concentrations are complex. Further studies
should be completed to ensure a better
understand of how TEP functions under ocean
acidification conditions.
Acknowledgements
• OA apprentices, technicians, and advisors!
–
Jim Murray, Evelyn Lessard, Mike Foy, Amanda Fay, Barbara Paul, Kelsey, Amy, Natsuko,
Jennifer, Kiely, Phil, Kelly, Andrew.
• Friday Harbor Labs
• Project Funding:
–
Educational Foundation of America and the National Science Fund for funding the project
–
Alice M. Barger and Andrea Reister for funding my education the past two years
–
Mary Gates Research Endowment Fund
• Steve Emerson and Kathy Krogsland for use of their lab equipment
at the UW
• My family, partner, friends, and current roommate, Collin, for all of
the great support
Works Cited
TEP Mesocosm Time Series
900.00
L-1)
700.00
TEP (mg Gum Xanthan
800.00
600.00
Why did TEP peak and then drop in
all treatments?
500.00
400.00
300.00
200.00
100.00
0.00
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Time (Days)
Figure 1. Transparent exopolymer particle time series based on median values. Error
bars are the median standard deviation Green data represent control mesocosms, red
high mesocosms, blue drift mesocosms, and black the dock. Statistically significant
differences were found between the drift and high treatment (0.848, p=0.001) and the
drift and control treatment (0.879, p=0.000).
900.00
TEP (mg Gum Xanthan
L-1)
800.00
What caused the
sudden decreased
in TEP?
700.00
600.00
500.00
400.00
300.00
200.00
100.00
0.00
0
2
4
6
8
10
12
14
16
18
20
1600
1400
pCO2
1200
1000
800
600
400
200
0
0
2
4
6
8
10
12
14
16
18
20
8.70
Temperature (°C)
8.60
• Unlikely due to
sampling error, present
in all bags
• Both Temperature and
pCO2 decrease in days
prior to TEP decrease
– Source says
temperature affects
TEP production?
8.50
8.40
8.30
8.20
8.10
8.00
0
2
4
6
8
10
12
Time (days)
14
16
18
20
Biotic Factor: Phytoplankton
70
60
50
Growth Rate
( cells days^-1)
• TEP production often
associated with
maintenance and
senescence phase of
phytoplankton
• Population of
Thalassiosira has
growth rates constant
and close to zero,
suggesting this is a
source of TEP
80
40
30
20
10
0
0
2
4
6
8
10
12
-10
-20
Time (days)
14
16
18
20
Experimental Results
Were there any significant differences in TEP
production between current water conditions
and the predicted future conditions?
There was no significant difference between
TEP production in the control treatment and
the high treatment, but the drift treatment
was different from the control and high.
What biotic factors was TEP correlated to
within our mesocosm?
TEP is significantly correlated to Chlorophyll
a, Biogenic Silica, and Bacteria Abundance.
Why was the drift significantly different from
the high and the control, but the high and
control were not different from each other?
higher production is most likely associated
with the repeatative enrichment of CO2 to
the control and high treatments but not the
drift
Why were initial TEP concentrations about
zero?
Turbulence during filling of the mesocosms
TEP Mesocosm Time Series
900
Median TEP (mg Gum Xanthan
L-1)
800
Why doesn’t TEP start at zero?
700
600
500
400
300
200
100
0
0
2
4
6
8
10
12
Time (Days)
14
16
18
20
Why were initial concentrations of
TEP above zero?
• Previous mesocosm
studies show increased
turbulence results in
increased TEP
formation in water
• Highly turbulent
conditions persistent
during mesocosm
filling
900
Median TEP (mg Gum Xanthan L-1)
800
700
600
500
400
300
200
100
0
0
2
4
6
8
10
12
Time (Days)
14
16
18
20
Biotic Factor: Phytoplankton
800
800
700
y = 22.623x + 152.07
r = 0.851
600
500
y = 19.285x + 167.47
r = 0.873
400
300
y = 23.279x + 131.3
r = 0.794
200
100
Median TEP (mg Gum Xanthan L-1)
Median TEP (mg Gum Xanthan L-1)
700
y = 61.23x - 13.772
r = 0.871
600
500
400
y = 43.341x + 11.007
r = 0.794
300
200
y = 47.171x + 7.0361
r = 0.687
100
p < 0.01
p < 0.01
0
0
0
5
10
15
20
Median Chlorophyll a (mg L-1)
25
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14
Median Biogenic Silica (mmol L-1)
Biotic Factor: Bacteria
800
• Two possible reasons
for this correlation:
• Currently no method for
discerning from a bulk
value whether TEP is
phytoplankton or bacteria
derived
– Bacteria are
remineralizing TEP
• Further information
necessary
Median TEP (mg Gum Xanthan L-1)
– Bacteria are producing
TEP
700
y = 0.0002x + 2.5189
r = 0.882
600
500
400
300
y = 0.0003x - 55.471
r = 0.754
200
y = 0.0002x - 28.908
r = 0.388
100
p < 0.05
0
0.00E+00
1.00E+06
2.00E+06
3.00E+06
4.00E+06
Median Bacterial Abundance (cell mL-1)