Better Oceanography throughOpticsChlorophyllPrimary ProductivityHarmful Algal BloomsChlorophyll ≈ Biomass(mg m-3)Ocean Color to EstimateBiomassChlorophyll0.1 1.0 10.0In situ Chl a (mg m-3)SeaWiFS Chl a10.01.00.1Adapted from Kahru & Mitchell 2001Ocean color and otherproperties to estimate primaryproductivityRecall:primary productivity is a rate (mg C m-2 d-1)The Phytoplankton Mantra: Light – Nutrients – TemperatureChlorophyll, temperature,light, and other properties canbe used to estimate primaryproductivitye.g….VGPM (vertically generalized productivity model)VGPM – EppleyCbPM (carbon based production model)There really are about as many models as there are researchersVGPM June 2005http://web.science.oregonstate.edu/ocean.productivity/VGPM - Eppley June 2005http://web.science.oregonstate.edu/ocean.productivity/CbPM June 2005http://web.science.oregonstate.edu/ocean.productivity/Oceanographers areconstantly refining theseproductivity modelsCase Study:Ecophysiological regimes, nutrientlimitation, and green-ness in the tropicalPacific OceanVol 442, 31 August 2006 doi:10.1038/nature05083Variable Fluorescence• Fv/Fm (Fm-Fo/Fm) provides an indication ofrelative “health”, or whether there is damage tothe photosystem• Short term changes (seconds) provide anindication of photosynthetic efficiency (quantumyield)• Long term changes (seconds – minutes) providean indication of adaptability• Do the same thing in ambient light, get anindication of photosynthetic ratesVariable Fluorescence can tell ussomething about cell “health” undernutrient limitationF01FmFvFoPhotochemical quenching occurs during dark reactionsIron limitation can alter this curve because of different efficiency of Flavodoxin vs. FerredoxinTimeBehrenfeld et al. 2006Tracking nutrient limitationusing variable fluorescenceBehrenfeld et al. 2006Fluorescence diagnostics delineatethreephysiological regimes in the tropicalPacificBehrenfeld et al. 2006Regions are divided based on Fv/Fm, pigment complex,and plastoquinone pooldynamicsBehrenfeld et al. 2006Possible remote sensing implicationsRegime 3: Iron stress causes “greening”night: pigment proteins plastoquinone poolFe Femorning: pigment proteinsplastoquinone poolVGPM - Eppley June 2005http://web.science.oregonstate.edu/ocean.productivity/Caveat emptor – Themodels are only as good asthe input dataOcean Color to detectharmful algal bloomsInsert Stumpf stuff herePhoto courtesy L. BrandChlorophyll alone is insufficientto distinguish bloom eventsStumpf et al. 2003Chlorophyll anomaly may bebetter to distinguish bloomeventsStumpf et al. 2003Forecasting model incorporatesocean color, physics, andchemistryStumpf et al. 2003SAMSON Over-flight Image, courtesy FERIQuasi-true color, stretched to emphasize ocean featuresPhotos courtesy R. KudelaAkashiwo sanguineaSanta CruzSeptember 12, 2006Develop optical signatures for diatoms anddinoflagellates present in Monterey BayDierssen et al. 2006DiatomDinoDiatomDinoDiatomDinoHydrolightSome useful referencesBehrenfeld, MJ, K Worthington, RM Sherrell, FP Chavez, P Strutton, MMcPhaden, DM Shea. 2006. Controls on tropical Pacific Oceanproductivity revealed through nutrient stress diagnostics. Nature. 442.doi: 10.1038/nature05083.Dierssen, HM, RM Kudela, JP Ryan, RC Zimmerman. 2006. Red and blacktides: Quantitative analysis of water-leaving radiance an perceivedcolor for phytoplankton, colored dissolved organic matter, andsuspended sediments. Limnology & Oceanography. 51(6): 2646-2659Nelson, NB, DA Siegel, CA Carlson, C Swan, WM Smethie, S Khatiwala.2007. Hydrography of chromophoric dissolved organic matter in theNorth Atlantic. Deep-Sea Research I. 54: 710 – 731.Stumpf, RP, ME Culver, PA Tester, M Tomlinson, GJ Kirkpatrick, BAPederson, E Truby, V Ransibrahmanakul, M Soracco. 2003. MonitoringKarenia brevis blooms in the Gulf of Mexico using satellite ocean colorimagery and other data. Harmful Algae. 2: 147 –