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Distribution of Algal Photosynthates As Seen Using Planar Optodes

Distribution of Algal Photosynthates As Seen Using Planar Optodes. Allison Gregg 3/5/11. Background on Coral-Algal Interactions. Coral reefs filled with great diversity of organisms Corals around the world are succumbing to environmental stressors How is algae playing a part?.

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Distribution of Algal Photosynthates As Seen Using Planar Optodes

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  1. Distribution of Algal Photosynthates As Seen Using Planar Optodes Allison Gregg 3/5/11

  2. Background on Coral-Algal Interactions • Coral reefs filled with great diversity of organisms • Corals around the world are succumbing to environmental stressors • How is algae playing a part? Top:http://www.sciencedaily.com/releases/2009/03/090320164659.htm Bottom: http://www.nytimes.com/2008/01/08/science/earth/08obalga.html

  3. What is Really Going On? • Microprobes have shown that coral-algae interaction zones are hypoxic • Leads to coral disease • What is the mechanism behind this? -microbe mediated? -or something else? • Planar optodes as a way to visualize what is happening Jennifer Smith, http://www.nceas.ucsb.edu/~jsmith/JenniferSmith-Research.htm

  4. What Are Planar Optodes? • a type of optical sensor used for visualizing various analyte concentrations • Able to visualize two dimensional space as opposed to electrodes • used for O2 ,CO2, pH, temperature ~2 cm

  5. How Do Oxygen Optodes Work? • Oxygen optode is made from a cocktail consisting of PtOEP indicator and coumarin antenna dye, immobilized in a polystyrene matrix • PtOEP signal is chemically dependent on analyte concentration; coumarin signal is independent of analyte • Analyte concentration calculated from ratio of fluorescence intensity of indicator: antenna ^Oxygen bubbled water^ ^Nitrogen bubbled water^

  6. Experimental Design • Original Hypothesis: Increase of flow leads to increased rates of photosynthesis in coral and macro algae • First, turf algae was placed in a chamber with no flow to determine baseline measurements of photosynthesis • What we found was surprising…

  7. Algae After Being Exposed to Light for Two Hours:

  8. Would We Get the Same Outcome with Flow? • Macro algae was put in front of optode sheet too see how oxygen was distributed in response to flow • Was there more diffusion through environment?

  9. When a Photosynthesizing Algae is Exposed to Flow

  10. What Does This Mean? • Oxygen released from algae during photosynthesis in discrete region- no diffusion • Respiration of algae from all around surrounding area • New Hypothesis: The distinct oxygen gradients produced from algae suggest that the position of coral to algae relative to direction of flow could play a part in the hypoxia along an interface.

  11. The Next Step • Does this pattern of distribution occur in other algae species or coral? • Glucose optode to see if DOC is released in same pattern as oxygen • Field work to see if these patterns at interaction zones can be seen in situ • Can a relationship between prevalence of coral disease and positioning of algae up current or down current from coral be found?

  12. Thanks to: Forest Rohwer Rohwer Labbies Andi Haas Morten Larsen Ronnie Glud Sergey Borisov Jen Smith Mark Hatay Peter Salamon Anca Segall Undergraduate Biomath group Funding: NSF-funded STEM Scholarship National Science Foundation Acknowledgements

  13. Ratio to Concentration • Ratio= (R-G)/G • This ratio is then used to determine the concentration using the Stern-Volmer equation: • C= (R0-R)/(Ksv(R0-R*)

  14. How Does Math Come into Play? • Actual concentration of oxygen is determined by using the modified Stern-Volmer equation: - R/R0=(f/1+Ksv1[O2] + (f-1)/ 1+Ksv2[O2]) Where f is the unquenchable fraction of the optode, R is the ratio at a certain [O2], R0 is ratio at anoxia, Ksv2=0, and Ksv1 is the slope of the line R0/R vs [O2]

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