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Toward autonomous measurements of photosynthetic electron transport rates: An evaluation of active fluorescence-based measurements of photochemistry

Silsbe, Greg M. and Oxborough, Kevin and Suggett, David J and Forster, Rodney M. and Ihnken, Sven and Komárek, Ondřej and Lawrenz, Evelyn and Prášil, Ondřej and Röttgers, Rüdiger and Šicner, Michal and Simis, Stefan G.H. and Van Dijk, Mark A. and Kromkamp, Jacco C. (2015) 'Toward autonomous measurements of photosynthetic electron transport rates: An evaluation of active fluorescence-based measurements of photochemistry.' Limnology and Oceanography: Methods, 13 (3). pp. 138-155. ISSN 1541-5856

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Abstract

This study presents a methods evaluation and intercalibration of active fluorescence-based measurements of the quantum yield (ϕʹ 0 PSII) and absorption coefficient (aPSII) of photosystem II (PSII) photochemistry. Measurements of ϕʹ PSII , aPSII, 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 of ϕ PSII and aPSII were 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 of ϕʹ PSII and the effective absorption cross section of PSII photochemistry (σPSII, a constituent of aPSII) 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 estimate aPSII(λ) and are evaluated here.With the exception of ex situ aPSII(λ) estimates from paired σPSII and PSII reaction center concentration ([RCII]) measurements, the accuracy and precision of in situ aPSII(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 autonomous P e measurements. This study supports the application of an instrument-specific calibration coefficient (KR) that scales minimum fluorescence in the dark (F 0 ) to aPSII as both the most accurate in situ measurement of aPSII, and the methodology best suited for highly resolved autonomous P e measurements.

Item Type: Article
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Biological Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 25 Feb 2019 10:52
Last Modified: 25 Feb 2019 10:52
URI: http://repository.essex.ac.uk/id/eprint/24117

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