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Mycosporine-like Amino Acids (MAAs) may serve to photoprotect phytoplankton from UV radiation Water soluble compounds Exhibit Absorption maxima from 310 to 360 nm Aminocyclohexenone or aminocyclohexenimine conjugated to amino acid or amino alcohol Found in dinoflagellates, prymnesiophytes, red algae, & cyano NH COOH OCH 3 O OHHO Mycosporine-Glycine max = 310 nm
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Model Calculations of Sunscreen Factors MAA UV +PAR Jtot Jo statistical a*ps ( ) Sunscreen Factors Ranged from roughly 40-60% Moisan & Mitchell 1998
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The Absorption Characteristics of Phaeocystis antarctica Moisan and Mitchell (1998) Ru Morrison, UNH
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Questions? Are there differences between MAA content between taxonomic groups? What determines MAA variability? How does MAA variability relate to other UV absorbing constituents e.g. CDOM (Mannino) and detritus.
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Field Samples Of Phaeocystis, Dinoflagellates & Diatoms HPLC Analysis Packaged a*ph (lambda) P/S & PP Pigments UV- MAAs Packaged Pigment Spectral Analysis Spectral Reconstruction\ Deconvolution French Press Method Analysis of pigment Packaging w.r.t. markers Forward Model Hydrolight to Test algorithms Inverse Model application Using Developed algorithms
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Approach 3 cruises in April, May June 2007 Collected optical, physiological, & chemical data Processing IOP & AOP data Approach of utilizing cultures to develop MAA standards
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_____________________________________ Cruise I: April 2007 Phaeocystis and co-dominated with diatoms such as small chains of Skeletonema Cruise II: May 2007 ( Dinoflagellates (Ceratium, Protoperidium, and heterotrophic dinoflagellates) and Diatoms Cruise III: June 2007 Mixture of Dinoflagellates and diatoms _____________________________________ **Confirmed from net tows and epif. quan. cell counts.
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Colonial Phaeocystis Dominated
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Diatom-Dinoflagellates Dominate
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Diatom Dominated
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MAA BIOME
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Assessing Pigment Package Effects What is the significance of packaging? Is packaging spectral? We founds significant variability in UV region due to packaging? Problem: Models are not spectrally corrected
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Major marker pigments Ubiquitous Chl a Unambiguous Alloxanthin Peridinin Prasinoxanthin Shared e.g. Fucoxanthin Chl b Zeaxanthin Violaxanthin
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Future Directions Understand how UV MAAs are expressed at the surface of the ocean as a remote sensing target Can they be seen in remote sensing reflectance? Can we assess physiological variability to constrain algorithms in order to increase accuracy and robustness?
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J “Jimmy Buffet’s Cheeseburger in Paradise” (Moisan 2008)
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