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Trichodesmium Biomass and Nitrogen fixation

Oceanographic Characterization During AEROSE: Bio-Optics, Nitrogen fixation, Trichodesmium Biomass and Photosynthetic Efficiency. José M. López, Julio M. Morell, Jorge E. Corredor, Ramón López, Alvaro Cabrera, Miguel Canals, Aurora Justiniano Marine Sciences Department

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Trichodesmium Biomass and Nitrogen fixation

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  1. Oceanographic Characterization During AEROSE: Bio-Optics, Nitrogen fixation, Trichodesmium Biomass and Photosynthetic Efficiency José M. López, Julio M. Morell, Jorge E. Corredor, Ramón López, Alvaro Cabrera, Miguel Canals, Aurora Justiniano Marine Sciences Department University of Puerto RicoMayagüez Campus

  2. MODIS Chlorophyll-a composite (March 2- 12, 2004) with the eastbound AEROSE cruise tract and station numbers

  3. Trichodesmium Biomass and Nitrogen fixation

  4. Oceanographic provinces were observed during AEROSE influenced by the Amazon River, Central Atlantic and the Mauritania upwellingRegion Longitude

  5. Trichodesmium Abundance Stations Surface Trichodesmium populations ranged form the highest (178 trichomes l -1) influenced by the Amazon River to none at the Mauritania Upwelling zone.

  6. Chlorophyll fraction 20 mm and Trichodesmium Salinity and Trichodesmium

  7. Central Atlantic Surface Trichodesmium (trichomes l-1) Sea Surface Model Upwelling zone Brazil A correlation between ocean topography and Trichodesmium Abundance was observed during AEROSE.

  8. Nitrogen fixation physiology was higher at the Amazon river influenced province. Nitrogen fixation is influenced by nutrient availability with phosphorous and iron as limiting factors.

  9. Bio Optics

  10. Mean Kd or diffuse attenuation coefficients for oceanographic stations obtained with the PRR-600 Profiling Radiometer

  11. Contour plot showing the percentage of photosynthetically available radiation (PAR) relative to surface irradiance along the AEROSE transect. Light intensity decreases eastward along isobaths due to enhanced light attenuation in the Mauritania upwelling region. Dashed line represents the base of the euphotic zone marked by the 1 % irradiance isolume.

  12. PhytoplanktonPhotosynthetic Efficiency during AEROSE

  13. Photosynthetic efficiency during AEROSE Atlantic Ocean Region Mauritania Upwelling Zone • Photosynthetic efficiency has been related with nutrient stress. • Variations in fluorescence quantum yield are observed as a result of nutrient availability • When this stress is alleviated as a result of an episodic nutrient pulse such as coastal upwelling, river water inputs, or Aeolian nutrient (e.g. iron) deposition, an increase in photosynthetic quantum yield is observed.

  14. Photosynthetic efficiency and Photosystem Absorbance Cross Section Lower Fv/Fm and higher σ PSII indicate that a nutrient (nitrate or iron) limitation of phytoplankton growth occurred. It is known that Fe or nitrogen limitations lead to a decrease in Fv /Fm and an increase in σ PSII

  15. Chlorophyll-a Specific absorption Spectra during AEROSE

  16. Mean Chlorophyll-a specific absorption coefficient The highest at surface 0.037 m2 (mg chl-a) -1 is observed for the March 6, 2004 sample, during the dust event. Surface DCM

  17. Chlorophyll-a Concentration at surface and DCM Highest Chlorophyll-a Concentration at surface observed for Station 5 with 0.80 ug/l ST= Station S= Surface

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