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This study explores how Mycosporine-like Amino Acids (MAAs) in phytoplankton act as photoprotective agents against UV radiation. These water-soluble compounds exhibit absorption maxima between 310 to 360 nm and are conjugated to amino acids or amino alcohols. They are found in dinoflagellates, prymnesiophytes, red algae, and cyanobacteria. Sunscreen factors ranged from 40-60%, with MAAs playing a crucial role in UV protection. The research investigates the variability of MAAs among different taxonomic groups and their relation to other UV-absorbing constituents like CDOM and detritus. The study also delves into spectral reconstruction and packaging effects of pigments, aiming to enhance remote sensing accuracy and robustness. Future directions include exploring the expression of UV MAAs at the ocean's surface and their detectability in remote sensing data for improved algorithm constraints.
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O OCH3 NH HO OH COOH 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 Mycosporine-Glycine max = 310 nm
Model Calculations of Sunscreen Factors UV +PAR Jtot statistical a*ps (l) MAA Jo Moisan & Mitchell 1998 Sunscreen Factors Ranged from roughly 40-60%
The Absorption Characteristics of Phaeocystis antarctica Moisan and Mitchell (1998) Ru Morrison , UNH
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.
Field Samples Of Phaeocystis, Dinoflagellates & Diatoms Packaged HPLC Analysis a*ph (lambda) Packaged Pigment Spectral Analysis P/S & PP Pigments UV- MAAs 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
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
_____________________________________Cruise I: April 2007Phaeocystis and co-dominated with diatoms such as small chains of SkeletonemaCruise II: May 2007 (Dinoflagellates (Ceratium, Protoperidium, and heterotrophic dinoflagellates) and DiatomsCruise III: June 2007Mixture of Dinoflagellates and diatoms_____________________________________**Confirmed from net tows and epif. quan. cell counts.
BIOME MAA
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
Major marker pigments Ubiquitous Chl a Unambiguous Alloxanthin Peridinin Prasinoxanthin Shared e.g. Fucoxanthin Chl b Zeaxanthin Violaxanthin
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?
