title: Photo-physiological variability in phytoplankton chlorophyll fluorescence and assessment of chlorophyll concentration.
abstract: Photo-physiological variability of in vivo chlorophyll fluorescence (CF) per unit of chlorophyll concentration (CC) is analyzed using a biophysical model to improve the accuracy of CC assessments. Field measurements of CF and photosystem II (PSII) photochemical yield (PY) with the Advanced Laser Fluorometer (ALF) in the Delaware and Chesapeake Bays are analyzed vs. high-performance liquid chromatography (HPLC) CC retrievals. It is shown that isolation from ambient light, PSII saturating excitation, optimized phytoplankton exposure to excitation, and phytoplankton dark adaptation may provide accurate in vivo CC fluorescence measurements (R2 = 0.90-0.95 vs. HPLC retrievals). For in situ or flow-through measurements that do not allow for dark adaptation, concurrent PY measurements can be used to adjust for CF non-photochemical quenching (NPQ) and improve the accuracy of CC fluorescence assessments. Field evaluation has shown the NPQ-invariance of CF/PY and CF(PY-1-1) parameters and their high correlation with HPLC CC retrievals (R2 = 0.74-0.96), while the NPQ-affected CF measurements correlated poorly with CC (R2 = -0.22).
authors: Lamont Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, New York 10964, USA. chekaluk@ldeo.columbia.edu
authors: Alexander
authors: A
authors: Chekalyuk
authors: Mark
authors: M
authors: Hafez
mesh_terms: D000222:Adaptation, Physiological / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003624:Darkness; D005453:Fluorescence; D005470:Fluorometry; D005843:Geography; D007834:Lasers; D008027:Light; D010839:Phytoplankton / Q000502:physiology* / Q000528:radiation effects*; D012767:Ships
chemical_list: D002734:Chlorophyll