The Priming Effect: Discovering the future of lake
carbon cycling Cassie Craig
Mentor: Jake Zwart
LakesLakes have recently been recognized as
important components of the global carbon cycle.
Leaves can fall into lakes and dissolve into the water column that contain carbon and can alter the internal carbon cycle.
CO2 emission from inland lakes is very similar to the CO2 uptake in the ocean and therefore has the same effect on the atmosphere.
What is the priming effect?
When labile organic matter (LOM) such as glucose, cellouse, or root exudates are in the soil…
It changes the mineralization rate of recalcitrant organic matter (ROM) present…
Therefore altering the amount of CO2 released in the atmosphere.
Priming effect can enhance the recalcitrant organic matter mineralization rate anywhere from 10% to 500%.
Priming Effect This all meaning that labile carbon (carbon that is easily
broken down from phytoplankton in aquatic systems) increases the rate that bacteria breaks down recalcitrant carbon (carbon that is hard to break down and comes from terrestrial sources such as trees.
Positive or Negative It is found that the priming effect could have
negative and positive effects.A negative effect is…
the labile organic matter decreasing recalcitrant organic matter mineralization rate
A positive effect is... labile organic matter (LOM) can increase recalcitrant
organic matter (ROM) mineralization rate.
(Guenet et al. 2010).
ImportanceSignificant findings for understanding current
and predicting future lake carbon cycling. Also changing our view of how lakes fit into the
global carbon cycle. There has not been much research on the
importance and mechanisms of the priming effect.
Some scientists do not believe it even exists in aquatic ecosystems.
HypothesisThat higher amount of labile carbon (glucose),
the higher the rate will be of recalcitrant carbon being broke down, increasing the amount of CO2 into the atmosphere.
MethodsLake water was collected from five lakes on
UNDERC property in the Upper Peninsula Michigan.
1. East Long2. West Long3. Hummingbird4. Crampton5. Morris
Methods Cont..The lake water was filtered through 0.2 µm filters to
remove any bacteria from the water.Leaving dissolved organic carbon behind with 100
mL of lake water used in each incubation bottle.
Methods Cont..Glucose was used as the source of labile organic
matter. Four treatment groups per lake: 0.25, 1.0, 2.25,
and 4.0 mg of glucose One control treatment for each lake. (no
glucose)One glucose control treatment per lake. (no lake
water)Three replicates for each treatment.
Methods Cont..All treatments had 1 mL of unfiltered lake water
added as the source of natural lake bacteria. Headspace gas from each sample was extracted
five times during the incubation after every 5 days and analyzed on a gas chromatograph to see how much CH4 and CO2 was released.
Another round of glucose was added in the second week to stimulate a pulse of fresh labile carbon. This reflects what would happen in a lake with a
phytoplankton bloom.
Results
1 2 3 4 50
1000
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6000
MO Control Cumulative MO 0.25 Cumulative MO 1.0 Cumulative MO 2.25 Cumulative MO 4.0 Cumulative
Week
Res
piration
ANOVA Test on SlopesMorris overall had a p-value of 0.0246 Within the treatments, only the control and the
4.0 mg of glucose were statically different in their slopes of carbon respired. p-value of 0.0194313
ANOVA Test on RespirationMorris overall had a p-value significant at
0.01617.The respiration rate that was statically different
was between the treatment groups of the control and 4.0 mg.
1 2 3 4 50
500
1000
1500
2000
2500
3000
EL Control CumulativeEL 0.25 CumulativeEL 1.0 CumulativeEL 2.25 CumulativeEL 4.0 Cumulative
Week
Resp
iratio
n
ANOVA test on SlopesEast Long slopes overall showed were significant
at a p-value of 0.00555.The treatments that were statically different
from one another was 2.25 and 0.25 with a p-value of 0.0448610
ANOVA Test on RespirationEast Long overall was significant at 0.125 The respiration rate that was statically different
was between the treatment groups was the control and 1.0 mg.
1 2 3 4 50
500
1000
1500
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2500
3000
3500
4000
4500
WL Control CumulativeWL 0.25 CumulativeWL 1.0 CumulativeWL 2.25 CumulativeWL 4.0 Cumulative
Week
Resp
iratio
n
ANOVA Test on SlopesWest Long overall had a significant p value at
0.00509. Within in West Long, the treatment slopes that
were statistically different from each other were…
4.0 mg and 0.25 at a p-value of 0.0588166.The control and 2.25 with a p-value at
0.02434633. The control and 4.0 mg at a p-value of
0.0037442.
ANOVA Test on RespirationWest Long was significant overall at 0.00138. The respiration rate that was statically
significant was between…The control and 0.25 mg at a p-value of
0.0035390The control and 4.0 mg at a p-value 0.0011113.
1 2 3 4 50
500
1000
1500
2000
2500
3000
3500
4000
HB Control CumulativeHB 0.25 CumulativeHB 1.0 CumulativeHB 2.25 CumulativeHB 4.0 Cumulative
Week
Resp
iratio
n
ANOVA Test on SlopesOverall the slopes of Hummingbird were not
statistically significant. p-value of 0.162
None of the treatment groups in that lake were statistically different from one another.
ANOVA Test on RespirationHummingbird respiration values overall were not
statically significant.p-value of 0.262.
The treatment groups compared to one another showed no significance as well.
1 2 3 4 50
200
400
600
800
1000
1200
1400
1600
1800
2000
CR Control CumulativeCR 0.25 CumulativeCR 1.0 CumulativeCR 2.25 CumulativeCR 4.0 Cumulative
Time
Resp
iratio
n
ANOVA Test on SlopesOverall the slopes of Crampton were not
statistically significantp-value of 0.134.
None one of the treatment groups in that lake were statistically different from one another.
ANOVA Test on RespirationCramptons’ respiration values overall were not
statically significant.p-value of and 0.147.
The treatment groups compared to one another showed no significance as well.
Conclusion The results of this experiment supported the
hypothesis that stated that the higher amount of labile carbon (glucose), the higher the rate of recalcitrant carbon being broke down there would be, increasing the amount of CO2 into the atmosphere.
The priming effect does exist in aquatic environments.
Further tested whether the contents of the lakes had an effect on how much CO2 was released such as the nutrients present.
References Attermeyer, K., Hornick, T., Kayler, Z. E., Bahr, A.,
Zwirnmann, E., Grossart, H.-P., and Premke, K. 2014. Enhanced bacterial decomposition with increasing addition of autochthonous to allochthonous carbon without any effect on bacterial community composition, Biogeosciences, 11, 1479-1489, doi:10.5194/bg-11-1479-2014.
Guenet B, Michael Danger, Luc Abbadie, and Gérard Lacroix 2010. Priming effect: bridging the gap between terrestrial and aquatic ecology. Ecology 91:2850–2861. doi.org/10.1890/09-1968.1
Tranviket Lars J. et.al. 2009. Lakes and reservoirs as regulators of carbon cycling and climate. Limnology and Oceanography, 54 part 2, 2298-2314. 10.4319/lo.2009.54.6_part_2.2298
Questions?