Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean
Abstract Active fluorescence measurements can provide rapid, non‐intrusive estimates of phytoplankton primary production at high spatial and temporal resolution, but there is uncertainty in converting from electrons to ecologically relevant rates of CO 2 assimilation. In this study, we examine the l...
Published in: | Limnology and Oceanography |
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Online Access: | http://dx.doi.org/10.1002/lno.10812 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Flno.10812 https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10812 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/lno.10812 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10812 |
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crwiley:10.1002/lno.10812 2024-06-02T08:14:46+00:00 Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean Ryan‐Keogh, Thomas J. Thomalla, Sandy J. Little, Hazel Melanson, Jenna‐Rose CSIR's Southern Ocean Carbon and Climate Observatory (SOCCO) Programme CSIR's Parliamentary Grant NRF SANAP 2018 http://dx.doi.org/10.1002/lno.10812 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Flno.10812 https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10812 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/lno.10812 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10812 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Limnology and Oceanography volume 63, issue 5, page 1856-1876 ISSN 0024-3590 1939-5590 journal-article 2018 crwiley https://doi.org/10.1002/lno.10812 2024-05-03T11:13:46Z Abstract Active fluorescence measurements can provide rapid, non‐intrusive estimates of phytoplankton primary production at high spatial and temporal resolution, but there is uncertainty in converting from electrons to ecologically relevant rates of CO 2 assimilation. In this study, we examine the light‐dependent rates of photosynthetic electron transport and 13 C‐uptake in the Atlantic sector of the Southern Ocean to derive a conversion factor for both winter (July 2015–August 2015) and summer (December 2015–February 2016). The results revealed significant seasonal differences in the light‐saturated chlorophyll specific rate of 13 C‐uptake, ( ), with mean summer values 2.3 times higher than mean winter values, and the light limited chlorophyll specific efficiency, ( α B ), with mean values 2.7 times higher in summer than in winter. Similar patterns were observed in the light‐saturated photosynthetic electron transport rates ( , 1.5 times higher in summer) and light limited photosynthetic electron transport efficiency ( α RCII , 1.3 times higher in summer). The conversion factor between carbon and electrons (Φ e:C (mol e − mol C −1 )) was derived utilizing in situ measurements of the chlorophyll‐normalized number of reaction centers ( n RCII ), resulting in a mean summer Φ e:C which was ∼ 3 times lower than the mean winter Φ e:C . Empirical relationships were established between Φ e:C , light and NPQ, however they were not consistent across locations or seasons. The seasonal decoupling of Φ e:C is the result of differences in E k ‐dependent and E k ‐independent variability, which require new modelling approaches and improvements to bio‐optical techniques to account for these inter‐seasonal differences in both taxonomy and environmental mean conditions. Article in Journal/Newspaper Southern Ocean Wiley Online Library Southern Ocean Limnology and Oceanography 63 5 1856 1876 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Active fluorescence measurements can provide rapid, non‐intrusive estimates of phytoplankton primary production at high spatial and temporal resolution, but there is uncertainty in converting from electrons to ecologically relevant rates of CO 2 assimilation. In this study, we examine the light‐dependent rates of photosynthetic electron transport and 13 C‐uptake in the Atlantic sector of the Southern Ocean to derive a conversion factor for both winter (July 2015–August 2015) and summer (December 2015–February 2016). The results revealed significant seasonal differences in the light‐saturated chlorophyll specific rate of 13 C‐uptake, ( ), with mean summer values 2.3 times higher than mean winter values, and the light limited chlorophyll specific efficiency, ( α B ), with mean values 2.7 times higher in summer than in winter. Similar patterns were observed in the light‐saturated photosynthetic electron transport rates ( , 1.5 times higher in summer) and light limited photosynthetic electron transport efficiency ( α RCII , 1.3 times higher in summer). The conversion factor between carbon and electrons (Φ e:C (mol e − mol C −1 )) was derived utilizing in situ measurements of the chlorophyll‐normalized number of reaction centers ( n RCII ), resulting in a mean summer Φ e:C which was ∼ 3 times lower than the mean winter Φ e:C . Empirical relationships were established between Φ e:C , light and NPQ, however they were not consistent across locations or seasons. The seasonal decoupling of Φ e:C is the result of differences in E k ‐dependent and E k ‐independent variability, which require new modelling approaches and improvements to bio‐optical techniques to account for these inter‐seasonal differences in both taxonomy and environmental mean conditions. |
author2 |
CSIR's Southern Ocean Carbon and Climate Observatory (SOCCO) Programme CSIR's Parliamentary Grant NRF SANAP |
format |
Article in Journal/Newspaper |
author |
Ryan‐Keogh, Thomas J. Thomalla, Sandy J. Little, Hazel Melanson, Jenna‐Rose |
spellingShingle |
Ryan‐Keogh, Thomas J. Thomalla, Sandy J. Little, Hazel Melanson, Jenna‐Rose Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean |
author_facet |
Ryan‐Keogh, Thomas J. Thomalla, Sandy J. Little, Hazel Melanson, Jenna‐Rose |
author_sort |
Ryan‐Keogh, Thomas J. |
title |
Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean |
title_short |
Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean |
title_full |
Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean |
title_fullStr |
Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean |
title_full_unstemmed |
Seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the Southern Ocean |
title_sort |
seasonal regulation of the coupling between photosynthetic electron transport and carbon fixation in the southern ocean |
publisher |
Wiley |
publishDate |
2018 |
url |
http://dx.doi.org/10.1002/lno.10812 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Flno.10812 https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10812 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/lno.10812 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10812 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Limnology and Oceanography volume 63, issue 5, page 1856-1876 ISSN 0024-3590 1939-5590 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/lno.10812 |
container_title |
Limnology and Oceanography |
container_volume |
63 |
container_issue |
5 |
container_start_page |
1856 |
op_container_end_page |
1876 |
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1800738747721973760 |