Influences of Changes in Salinity on Release of Carbon by Phytoplankton

Jessica Wagner

Century High School

OGI & OHSU

Lab, Field, and Modeling Study

Mentors:

Tawnya Peterson

Joe Needoba

Karen Watanabe

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CMOP

• Field work• Modeling • In Situ Data• Lab Experiments

Center for Coastal Margin Observation & Prediction

Project Relevance

Water Samples, Carbon Model, Salinity Experiments

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Focus/Question

•Where fresh water meets salt water•Has many changes in salinity over short periods of time•Important for fish-creates a habitat•Biologically very productive

Question: How does the change in salinity affect the growth rate of freshwater Diatoms?

Estuary

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CDOM Cast Data

0

5

10

15

20

0 500 1000 1500 2000 2500 3000

CDOM-RFU (Cast 151)

De

pth

(m

)

CDOM Colored dissolved

organic matter http://www.gcrio.org

5Surirella sella

• Under salinity stress diatoms produce a larger amount of CDOM

• Eventually osmosis will cause the cell to shrink/burst

Observations

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Analysis of Variants (ANOVA)

x 10-3

5 10 15 20 25 30 35 40 45 502

4

6

8

10

12

14

Slo

pes

Growth Rate vs.

Salinity

Salinity (PSU)

Conclusion: Growth rates are

significantly different on the salinity range

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Salinity affects growth

What does this mean for the estuary and carbon cycling?

Salinity experiments that can show effect of changes in salinity on carbohydrates are needed

How do changes in salinity affect dissolved carbon release by phytoplankton?

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Salinity Experiment -May

FW-Control½ filtered fw½ none filtered fwSW-Shock½ Filtered sw½ none filtered fw

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Salinity Experiment-July

FW-Control½ filtered fw½ none filtered fwSW-Shock½ Filtered sw½ none filtered fw

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Summary

• Salinity affects growth of diatom • CDOM release increased as salt water was

added to fresh water phytoplankton• However, No effect on July Salinity

experiment – Different Seasons, Different Location in the river,

Different species (Salt-tolerant)

• Future Hypothesis/Testing– Different salt tolerance on other species of diatoms

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Thank You

-My Mentors Tawnya Peterson, Joe Needoba, and Karen Watanabe

-K-12 Director Karen Wegner-CMOP-ASE