1. Chlorophyll a in the lower Cape Fear Estuary Leilani McMillan The University of North Carolina at Wilmington November 29, 2010

2. Chlorophyll a Chlorophyll – Green pigment common to photosynthetic cells – Absorbs all wavelengths of visible light, except green – Three types: a, b, c Chlorophyll a – Photosynthetic pigment present in chloroplast – R=CH 3 – Complex arrangement of alternating single and double bonds in the porphyrin ring are optimal for absorbing light

3. Chlorophyll a Absorbs energy around wavelengths 430nm and 662nm While accessory pigments, absorb what chlorophyll a does not

4. Why measure chlorophyll a “Estimate” the spatial and temporal variability of planktonic biomass Only an “estimate” since abundance of chlorophyll a per cell varies Taxonomic distinction is based on distribution between different pigments Different pigments help identify types of algae present in sample

5. How to measure chlorophyll a Fluorescence – Sensitive, cheap, not affected by turbidity – Must use standards, less precise, noisier background Absorbance – No standards, all chlorophyll concentrations – Turbidity interference, slower Chlorophyll fluoresces around 665nm, excites around 440nm

6. How to measure chlorophyll a Obtain water samples Samples were then filtered Frozen until further analysis Soaked in acetone for 24 hours Fluorescence

7. Chlorophyll a

8. Chlorophyll a Surface

9. Chlorophyll a Deep

10. Comparing 2010 results to class average over the past 5 years Increase of Chl a surface on cruise 1, but decrease on cruise 2 Increase of Chl a deep on both cruise 1 and 2

11. Other affects of chlorophyll a in the Cape Fear? Light attenuation (Kd) Salinity Turbidity DOC

12. Light Attenuation Chlorophyll concentration higher when Kd was low Kd increases, chlorophyll concentration decreases Higher Kd value, less light, low chlorophyll concentration Cruise 1 exhibited higher concentrations of chlorophyll

13. Light Attenuation Chlorophyll decreases as Kd value increases Less light available for photosynthesis

14. Salinity Salinity has little significance on chlorophyll concentration Linear correlation Salinity increase, chlorophyll concentration increased

15. Turbidity Turbidity has little effect on the chlorophyll a concentration Increase in turbidity, there is a decrease in chlorophyll a concentration

16. Turbidity Cruise 1 Turbidity increases, resulting in a decrease in chl a Cruise 2 Little effect with presence of turbidity

17. DOC Presence in surface water samples causes decrease in chlorophyll concentration

18. DOC The presence of DOC on cruise one seems to be affect Chl a concentration DOC increase led to a decline in Chl a Cruise two had no significant effects from DOC

19. Conclusion Chlorophyll concentration was much higher in September compared to November More light available results in production of chlorophyll Increase in chlorophyll due to clearer water, when there was an increase in salinity Presence of turbidity and DOC, tends to reduce chlorophyll concentration

20. References Dr. Robert Kieber lecture notes http://www.emc.maricopa.edu/faculty/farabe e/BIOBK/BioBookPS.html (accessed on November 22, 2010) http://www.emc.maricopa.edu/faculty/farabe e/BIOBK/BioBookPS.html