Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific
Active chlorophyll a fluorescence approaches, including fast repetition rate fluorometry (FRRF), have the potential to provide estimates of phytoplankton primary productivity at an unprecedented spatial and temporal resolution. FRRF-derived productivity rates are based on estimates of charge separat...
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ftdoajarticles:oai:doaj.org/article:6d7b4ece29d14100a89c23807608ee86 2023-05-15T18:28:18+02:00 Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific N. Schuback M. Flecken M. T. Maldonado P. D. Tortell 2016-02-01T00:00:00Z https://doi.org/10.5194/bg-13-1019-2016 https://doaj.org/article/6d7b4ece29d14100a89c23807608ee86 EN eng Copernicus Publications http://www.biogeosciences.net/13/1019/2016/bg-13-1019-2016.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-13-1019-2016 https://doaj.org/article/6d7b4ece29d14100a89c23807608ee86 Biogeosciences, Vol 13, Iss 4, Pp 1019-1035 (2016) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2016 ftdoajarticles https://doi.org/10.5194/bg-13-1019-2016 2022-12-31T01:37:53Z Active chlorophyll a fluorescence approaches, including fast repetition rate fluorometry (FRRF), have the potential to provide estimates of phytoplankton primary productivity at an unprecedented spatial and temporal resolution. FRRF-derived productivity rates are based on estimates of charge separation in reaction center II (ETR RCII ), which must be converted into ecologically relevant units of carbon fixation. Understanding sources of variability in the coupling of ETR RCII and carbon fixation provides physiological insight into phytoplankton photosynthesis and is critical for the application of FRRF as a primary productivity measurement tool. In the present study, we simultaneously measured phytoplankton carbon fixation and ETR RCII in the iron-limited NE subarctic Pacific over the course of a diurnal cycle. We show that rates of ETR RCII are closely tied to the diurnal cycle in light availability, whereas rates of carbon fixation appear to be influenced by endogenous changes in metabolic energy allocation under iron-limited conditions. Unsynchronized diurnal oscillations of the two rates led to 3.5-fold changes in the conversion factor between ETR RCII and carbon fixation ( K c / n PSII ). Consequently, diurnal variability in phytoplankton carbon fixation cannot be adequately captured with FRRF approaches if a constant conversion factor is applied. Utilizing several auxiliary photophysiological measurements, we observed that a high conversion factor is associated with conditions of excess light and correlates with the increased expression of non-photochemical quenching (NPQ) in the pigment antenna, as derived from FRRF measurements. The observed correlation between NPQ and K c / n PSII requires further validation but has the potential to improve estimates of phytoplankton carbon fixation rates from FRRF measurements alone. Article in Journal/Newspaper Subarctic Directory of Open Access Journals: DOAJ Articles Pacific Biogeosciences 13 4 1019 1035 |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 N. Schuback M. Flecken M. T. Maldonado P. D. Tortell Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Active chlorophyll a fluorescence approaches, including fast repetition rate fluorometry (FRRF), have the potential to provide estimates of phytoplankton primary productivity at an unprecedented spatial and temporal resolution. FRRF-derived productivity rates are based on estimates of charge separation in reaction center II (ETR RCII ), which must be converted into ecologically relevant units of carbon fixation. Understanding sources of variability in the coupling of ETR RCII and carbon fixation provides physiological insight into phytoplankton photosynthesis and is critical for the application of FRRF as a primary productivity measurement tool. In the present study, we simultaneously measured phytoplankton carbon fixation and ETR RCII in the iron-limited NE subarctic Pacific over the course of a diurnal cycle. We show that rates of ETR RCII are closely tied to the diurnal cycle in light availability, whereas rates of carbon fixation appear to be influenced by endogenous changes in metabolic energy allocation under iron-limited conditions. Unsynchronized diurnal oscillations of the two rates led to 3.5-fold changes in the conversion factor between ETR RCII and carbon fixation ( K c / n PSII ). Consequently, diurnal variability in phytoplankton carbon fixation cannot be adequately captured with FRRF approaches if a constant conversion factor is applied. Utilizing several auxiliary photophysiological measurements, we observed that a high conversion factor is associated with conditions of excess light and correlates with the increased expression of non-photochemical quenching (NPQ) in the pigment antenna, as derived from FRRF measurements. The observed correlation between NPQ and K c / n PSII requires further validation but has the potential to improve estimates of phytoplankton carbon fixation rates from FRRF measurements alone. |
format |
Article in Journal/Newspaper |
author |
N. Schuback M. Flecken M. T. Maldonado P. D. Tortell |
author_facet |
N. Schuback M. Flecken M. T. Maldonado P. D. Tortell |
author_sort |
N. Schuback |
title |
Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific |
title_short |
Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific |
title_full |
Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific |
title_fullStr |
Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific |
title_full_unstemmed |
Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific |
title_sort |
diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the ne subarctic pacific |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/bg-13-1019-2016 https://doaj.org/article/6d7b4ece29d14100a89c23807608ee86 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Subarctic |
genre_facet |
Subarctic |
op_source |
Biogeosciences, Vol 13, Iss 4, Pp 1019-1035 (2016) |
op_relation |
http://www.biogeosciences.net/13/1019/2016/bg-13-1019-2016.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-13-1019-2016 https://doaj.org/article/6d7b4ece29d14100a89c23807608ee86 |
op_doi |
https://doi.org/10.5194/bg-13-1019-2016 |
container_title |
Biogeosciences |
container_volume |
13 |
container_issue |
4 |
container_start_page |
1019 |
op_container_end_page |
1035 |
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1766210709201354752 |