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Toward autonomous measurements of photosynthetic electron transport rates: An evaluation of active fluorescence‐based measurements of photochemistry
Author(s) -
Silsbe Greg M.,
Oxborough Kevin,
Suggett David J.,
Forster Rodney M.,
Ihnken Sven,
Komárek Ondřej,
Lawrenz Evelyn,
Prášil Ondřej,
Röttgers Rüdiger,
Šicner Michal,
Simis Stefan G.H.,
Van Dijk Mark A.,
Kromkamp Jacco C.
Publication year - 2015
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.1002/lom3.10014
Subject(s) - photosynthesis , absorption (acoustics) , irradiance , photosystem ii , fluorescence , quantum yield , chlorophyll fluorescence , chemistry , biological system , environmental science , analytical chemistry (journal) , optics , physics , environmental chemistry , biology , biochemistry
This study presents a methods evaluation and intercalibration of active fluorescence‐based measurements of the quantum yield ( ϕ PSII ′ ) and absorption coefficient ( a PSII) of photosystem II (PSII) photochemistry. Measurements ofϕ PSII ′ ,a PSII, and irradiance ( E ) can be scaled to derive photosynthetic electron transport rates ( P e ), the process that fuels phytoplankton carbon fixation and growth. Bio‐optical estimates ofϕ PSII ′anda PSIIwere evaluated using 10 phytoplankton cultures across different pigment groups with varying bio‐optical absorption characteristics on six different fast‐repetition rate fluorometers that span two different manufacturers and four different models. Culture measurements ofϕ PSII ′and the effective absorption cross section of PSII photochemistry ( σ PSII, a constituent ofa PSII) showed a high degree of correspondence across instruments, although some instrument‐specific biases are identified. A range of approaches have been used in the literature to estimatea PSII( λ )and are evaluated here. With the exception of ex situa PSII( λ )estimates from pairedσ PSIIand PSII reaction center concentration ( [ RCII ] ) measurements, the accuracy and precision of in situa PSII( λ )methodologies are largely determined by the variance of method‐specific coefficients. The accuracy and precision of these coefficients are evaluated, compared to literature data, and discussed within a framework of autonomousP emeasurements. This study supports the application of an instrument‐specific calibration coefficient ( K R ) that scales minimum fluorescence in the dark ( F 0 ) toa PSIIas both the most accurate in situ measurement ofa PSII, and the methodology best suited for highly resolved autonomousP emeasurements.© 2014 Association for the Sciences of Limnology and Oceanography