Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX
Chlorophyll fluorescence, primarily used to derive phytoplankton biomass, has long been an underutilized source of information on phytoplankton physiology. Diel fluctuations in chlorophyll fluorescence are affected by both photosynthetic efficiency and non-photochemical quenching (NPQ), where NPQ is...
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ftfrontimediafig:oai:figshare.com:article/12247511 2023-05-15T13:32:10+02:00 Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX Thomas J. Ryan-Keogh Sandy J. Thomalla 2020-05-05T04:51:22Z https://doi.org/10.3389/fmars.2020.00275.s001 https://figshare.com/articles/Table_1_Deriving_a_Proxy_for_Iron_Limitation_From_Chlorophyll_Fluorescence_on_Buoyancy_Gliders_DOCX/12247511 unknown doi:10.3389/fmars.2020.00275.s001 https://figshare.com/articles/Table_1_Deriving_a_Proxy_for_Iron_Limitation_From_Chlorophyll_Fluorescence_on_Buoyancy_Gliders_DOCX/12247511 CC BY 4.0 CC-BY Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering iron fluorescence gliders chlorophyll non-photochemical chlorophyll fluorescence quenching Dataset 2020 ftfrontimediafig https://doi.org/10.3389/fmars.2020.00275.s001 2020-05-06T22:53:52Z Chlorophyll fluorescence, primarily used to derive phytoplankton biomass, has long been an underutilized source of information on phytoplankton physiology. Diel fluctuations in chlorophyll fluorescence are affected by both photosynthetic efficiency and non-photochemical quenching (NPQ), where NPQ is a decrease in fluorescence through the dissipation of excess energy as heat. NPQ variability is linked to iron and light availability, and has the potential to provide important diagnostic information on phytoplankton physiology. Here we establish a relationship between NPQ sv (Stern-Volmer NPQ) and indices of iron limitation from nutrient addition experiments in the sub-Antarctic zone (SAZ) of the Atlantic Southern Ocean, through the derivation of NPQ max (the maximum NPQ sv value) and α NPQ (the light limited slope of NPQ sv ). Significant differences were found for both F v /F m and α NPQ for iron versus control treatments, with no significant differences for NPQ max . Similar results from CTDs indicated that changes in NPQ were driven by increasing light availability from late July to December, but by both iron and light from January to February. We propose here that variability in α NPQ , which has removed the effect of light availability, can potentially be used as a proxy for iron limitation (as shown here for the Atlantic SAZ), with higher values being associated with greater iron stress. This approach was transferred to data from a buoyancy glider deployment at the same location by utilizing the degree of fluorescence quenching as a proxy for NPQ G lider , which was plotted against in situ light to determine α NPQ. Seasonal increases in α NPQ are consistent with increased light availability, shoaling of the mixed layer depth (MLD) and anticipated seasonal iron limitation. The transition from winter to summer, when positive net heat flux dominates stratification, was coincident with a 24% increase in α NPQ variability and a switch in the dominant driver from incident PAR to MLD. The dominant scales of α NPQ ... Dataset Antarc* Antarctic Southern Ocean Frontiers: Figshare Antarctic Southern Ocean |
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Frontiers: Figshare |
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ftfrontimediafig |
language |
unknown |
topic |
Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering iron fluorescence gliders chlorophyll non-photochemical chlorophyll fluorescence quenching |
spellingShingle |
Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering iron fluorescence gliders chlorophyll non-photochemical chlorophyll fluorescence quenching Thomas J. Ryan-Keogh Sandy J. Thomalla Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX |
topic_facet |
Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering iron fluorescence gliders chlorophyll non-photochemical chlorophyll fluorescence quenching |
description |
Chlorophyll fluorescence, primarily used to derive phytoplankton biomass, has long been an underutilized source of information on phytoplankton physiology. Diel fluctuations in chlorophyll fluorescence are affected by both photosynthetic efficiency and non-photochemical quenching (NPQ), where NPQ is a decrease in fluorescence through the dissipation of excess energy as heat. NPQ variability is linked to iron and light availability, and has the potential to provide important diagnostic information on phytoplankton physiology. Here we establish a relationship between NPQ sv (Stern-Volmer NPQ) and indices of iron limitation from nutrient addition experiments in the sub-Antarctic zone (SAZ) of the Atlantic Southern Ocean, through the derivation of NPQ max (the maximum NPQ sv value) and α NPQ (the light limited slope of NPQ sv ). Significant differences were found for both F v /F m and α NPQ for iron versus control treatments, with no significant differences for NPQ max . Similar results from CTDs indicated that changes in NPQ were driven by increasing light availability from late July to December, but by both iron and light from January to February. We propose here that variability in α NPQ , which has removed the effect of light availability, can potentially be used as a proxy for iron limitation (as shown here for the Atlantic SAZ), with higher values being associated with greater iron stress. This approach was transferred to data from a buoyancy glider deployment at the same location by utilizing the degree of fluorescence quenching as a proxy for NPQ G lider , which was plotted against in situ light to determine α NPQ. Seasonal increases in α NPQ are consistent with increased light availability, shoaling of the mixed layer depth (MLD) and anticipated seasonal iron limitation. The transition from winter to summer, when positive net heat flux dominates stratification, was coincident with a 24% increase in α NPQ variability and a switch in the dominant driver from incident PAR to MLD. The dominant scales of α NPQ ... |
format |
Dataset |
author |
Thomas J. Ryan-Keogh Sandy J. Thomalla |
author_facet |
Thomas J. Ryan-Keogh Sandy J. Thomalla |
author_sort |
Thomas J. Ryan-Keogh |
title |
Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX |
title_short |
Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX |
title_full |
Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX |
title_fullStr |
Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX |
title_full_unstemmed |
Table_1_Deriving a Proxy for Iron Limitation From Chlorophyll Fluorescence on Buoyancy Gliders.DOCX |
title_sort |
table_1_deriving a proxy for iron limitation from chlorophyll fluorescence on buoyancy gliders.docx |
publishDate |
2020 |
url |
https://doi.org/10.3389/fmars.2020.00275.s001 https://figshare.com/articles/Table_1_Deriving_a_Proxy_for_Iron_Limitation_From_Chlorophyll_Fluorescence_on_Buoyancy_Gliders_DOCX/12247511 |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
doi:10.3389/fmars.2020.00275.s001 https://figshare.com/articles/Table_1_Deriving_a_Proxy_for_Iron_Limitation_From_Chlorophyll_Fluorescence_on_Buoyancy_Gliders_DOCX/12247511 |
op_rights |
CC BY 4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.3389/fmars.2020.00275.s001 |
_version_ |
1766024734375411712 |