Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone
The high nutrient–low chlorophyll condition of the Southern Ocean is generally thought to be caused by the low bioavailability of micronutrients, particularly iron, which plays an integral role in phytoplankton photosynthesis. Nevertheless, the Southern Ocean experiences seasonal blooms that general...
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ftcopernicus:oai:publications.copernicus.org:bg108492 2023-08-27T04:05:43+02:00 Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone Singh, Asmita Fietz, Susanne Thomalla, Sandy J. Sanchez, Nicolas Ardelan, Murat V. Moreau, Sébastien Kauko, Hanna M. Fransson, Agneta Chierici, Melissa Samanta, Saumik Mtshali, Thato N. Roychoudhury, Alakendra N. Ryan-Keogh, Thomas J. 2023-07-31 application/pdf https://doi.org/10.5194/bg-20-3073-2023 https://bg.copernicus.org/articles/20/3073/2023/ eng eng doi:10.5194/bg-20-3073-2023 https://bg.copernicus.org/articles/20/3073/2023/ eISSN: 1726-4189 Text 2023 ftcopernicus https://doi.org/10.5194/bg-20-3073-2023 2023-08-07T16:24:18Z The high nutrient–low chlorophyll condition of the Southern Ocean is generally thought to be caused by the low bioavailability of micronutrients, particularly iron, which plays an integral role in phytoplankton photosynthesis. Nevertheless, the Southern Ocean experiences seasonal blooms that generally initiate in austral spring, peak in summer, and extend into autumn. This seasonal increase in primary productivity is typically linked to the seasonal characteristics of nutrient and light supply. To better understand the potential limitations on productivity in the Antarctic sea-ice zone (SIZ), the photophysiological response of phytoplankton to iron addition (2.0 nM FeCl 3 ) was investigated during autumn along the Antarctic coast off Dronning Maud Land. Five short-term (24 h) incubation experiments were conducted around Astrid Ridge (68 ∘ S) and along a 6 ∘ E transect, where an autumn bloom was identified in the region of the western SIZ. Surface iron concentrations ranged from 0.27 to 1.39 nM around Astrid Ridge, and 0.56 to 0.63 nM along the 6 ∘ E transect. Contrary to expectation, the photophysiological response of phytoplankton to iron addition, measured through the photosynthetic efficiency and the absorption cross-section for photosystem II, showed no significant responses. It is thus proposed that since the autumn phytoplankton in the SIZ exhibited a lack of an iron limitation at the time of sampling, the ambient iron concentrations may have been sufficient to fulfil the cellular requirements. This provides new insights into extended iron replete post-bloom conditions in the typically assumed iron deficient high nutrient–low chlorophyll Southern Ocean. Text Antarc* Antarctic Dronning Maud Land Sea ice Southern Ocean Copernicus Publications: E-Journals Antarctic Southern Ocean The Antarctic Austral Dronning Maud Land Astrid Ridge ENVELOPE(12.000,12.000,-68.000,-68.000) Biogeosciences 20 14 3073 3091 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The high nutrient–low chlorophyll condition of the Southern Ocean is generally thought to be caused by the low bioavailability of micronutrients, particularly iron, which plays an integral role in phytoplankton photosynthesis. Nevertheless, the Southern Ocean experiences seasonal blooms that generally initiate in austral spring, peak in summer, and extend into autumn. This seasonal increase in primary productivity is typically linked to the seasonal characteristics of nutrient and light supply. To better understand the potential limitations on productivity in the Antarctic sea-ice zone (SIZ), the photophysiological response of phytoplankton to iron addition (2.0 nM FeCl 3 ) was investigated during autumn along the Antarctic coast off Dronning Maud Land. Five short-term (24 h) incubation experiments were conducted around Astrid Ridge (68 ∘ S) and along a 6 ∘ E transect, where an autumn bloom was identified in the region of the western SIZ. Surface iron concentrations ranged from 0.27 to 1.39 nM around Astrid Ridge, and 0.56 to 0.63 nM along the 6 ∘ E transect. Contrary to expectation, the photophysiological response of phytoplankton to iron addition, measured through the photosynthetic efficiency and the absorption cross-section for photosystem II, showed no significant responses. It is thus proposed that since the autumn phytoplankton in the SIZ exhibited a lack of an iron limitation at the time of sampling, the ambient iron concentrations may have been sufficient to fulfil the cellular requirements. This provides new insights into extended iron replete post-bloom conditions in the typically assumed iron deficient high nutrient–low chlorophyll Southern Ocean. |
format |
Text |
author |
Singh, Asmita Fietz, Susanne Thomalla, Sandy J. Sanchez, Nicolas Ardelan, Murat V. Moreau, Sébastien Kauko, Hanna M. Fransson, Agneta Chierici, Melissa Samanta, Saumik Mtshali, Thato N. Roychoudhury, Alakendra N. Ryan-Keogh, Thomas J. |
spellingShingle |
Singh, Asmita Fietz, Susanne Thomalla, Sandy J. Sanchez, Nicolas Ardelan, Murat V. Moreau, Sébastien Kauko, Hanna M. Fransson, Agneta Chierici, Melissa Samanta, Saumik Mtshali, Thato N. Roychoudhury, Alakendra N. Ryan-Keogh, Thomas J. Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone |
author_facet |
Singh, Asmita Fietz, Susanne Thomalla, Sandy J. Sanchez, Nicolas Ardelan, Murat V. Moreau, Sébastien Kauko, Hanna M. Fransson, Agneta Chierici, Melissa Samanta, Saumik Mtshali, Thato N. Roychoudhury, Alakendra N. Ryan-Keogh, Thomas J. |
author_sort |
Singh, Asmita |
title |
Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone |
title_short |
Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone |
title_full |
Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone |
title_fullStr |
Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone |
title_full_unstemmed |
Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone |
title_sort |
absence of photophysiological response to iron addition in autumn phytoplankton in the antarctic sea-ice zone |
publishDate |
2023 |
url |
https://doi.org/10.5194/bg-20-3073-2023 https://bg.copernicus.org/articles/20/3073/2023/ |
long_lat |
ENVELOPE(12.000,12.000,-68.000,-68.000) |
geographic |
Antarctic Southern Ocean The Antarctic Austral Dronning Maud Land Astrid Ridge |
geographic_facet |
Antarctic Southern Ocean The Antarctic Austral Dronning Maud Land Astrid Ridge |
genre |
Antarc* Antarctic Dronning Maud Land Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Dronning Maud Land Sea ice Southern Ocean |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-20-3073-2023 https://bg.copernicus.org/articles/20/3073/2023/ |
op_doi |
https://doi.org/10.5194/bg-20-3073-2023 |
container_title |
Biogeosciences |
container_volume |
20 |
container_issue |
14 |
container_start_page |
3073 |
op_container_end_page |
3091 |
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1775357460607926272 |