Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank
Sea-ice algae play a crucial role in the ecology and biogeochemistry of sea-ice zones. They not only comprise the base of sea-ice ecosystems, but also seed populations of extensive ice-edge blooms during ice melt. Ice algae must rapidly acclimate to dynamic light environments, from the low light und...
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Frontiers Media S.A.
2021
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Online Access: | https://doi.org/10.3389/fmars.2021.632087 https://doaj.org/article/ca33d01668844a298610d2c79f9549b0 |
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ftdoajarticles:oai:doaj.org/article:ca33d01668844a298610d2c79f9549b0 2023-05-15T13:50:12+02:00 Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank Kazuhiro Yoshida Andreas Seger Matthew Corkill Petra Heil Kristen Karsh Andrew McMinn Koji Suzuki 2021-03-01T00:00:00Z https://doi.org/10.3389/fmars.2021.632087 https://doaj.org/article/ca33d01668844a298610d2c79f9549b0 EN eng Frontiers Media S.A. https://www.frontiersin.org/articles/10.3389/fmars.2021.632087/full https://doaj.org/toc/2296-7745 2296-7745 doi:10.3389/fmars.2021.632087 https://doaj.org/article/ca33d01668844a298610d2c79f9549b0 Frontiers in Marine Science, Vol 8 (2021) sea-ice diatom pack ice iron limitation ice-edge bloom Southern Ocean chlorophyll a fluorescence Science Q General. Including nature conservation geographical distribution QH1-199.5 article 2021 ftdoajarticles https://doi.org/10.3389/fmars.2021.632087 2022-12-31T07:47:30Z Sea-ice algae play a crucial role in the ecology and biogeochemistry of sea-ice zones. They not only comprise the base of sea-ice ecosystems, but also seed populations of extensive ice-edge blooms during ice melt. Ice algae must rapidly acclimate to dynamic light environments, from the low light under sea ice to high light within open waters. Recently, iron (Fe) deficiency has been reported for diatoms in eastern Antarctic pack ice. Low Fe availability reduces photosynthetic plasticity, leading to reduced ice-algal primary production. We developed a low-Fe ice tank to manipulate Fe availability in sea ice. Over 20 days in the ice tank, the Antarctic ice diatom Fragilariopsis cylindrus was incubated in artificial low-Fe sea ice ([total Fe] = 20 nM) in high light (HL) and low light (LL) conditions. Melted ice was also exposed to intense light to simulate light conditions typical for melting ice in situ. When diatoms were frozen in, the maximum photochemical quantum efficiency of photosystem II (PSII), Fv/Fm, was suppressed by freezing stress. However, the diatoms maintained photosynthetic capability throughout the ice periods with a stable Fv/Fm value and increased photoprotection through non-photochemical quenching (NPQ) via photoprotective xanthophyll cycling (XC) and increased photoprotective carotenoid levels compared to pre-freeze-up. Photoprotection was more pronounced in the HL treatment due to greater light stress. However, the functional absorption cross section of PSII, σPSII, in F. cylindrus consistently increased after freezing, especially in the LL treatment (σPSII > 10 nm2 PSII–1). Our study is the first to report such a large σPSII in ice diatoms at low Fe conditions. When the melted sea ice was exposed to high light, Fv/Fm was suppressed. NPQ and XC were slightly upregulated, but not to values normally observed when Fe is not limiting, which indicates reduced photosynthetic flexibility to adapt to environmental changes during ice melt under low Fe conditions. Although ice algae can optimize ... Article in Journal/Newspaper Antarc* Antarctic ice algae Sea ice Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Southern Ocean The Antarctic Frontiers in Marine Science 8 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
sea-ice diatom pack ice iron limitation ice-edge bloom Southern Ocean chlorophyll a fluorescence Science Q General. Including nature conservation geographical distribution QH1-199.5 |
spellingShingle |
sea-ice diatom pack ice iron limitation ice-edge bloom Southern Ocean chlorophyll a fluorescence Science Q General. Including nature conservation geographical distribution QH1-199.5 Kazuhiro Yoshida Andreas Seger Matthew Corkill Petra Heil Kristen Karsh Andrew McMinn Koji Suzuki Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank |
topic_facet |
sea-ice diatom pack ice iron limitation ice-edge bloom Southern Ocean chlorophyll a fluorescence Science Q General. Including nature conservation geographical distribution QH1-199.5 |
description |
Sea-ice algae play a crucial role in the ecology and biogeochemistry of sea-ice zones. They not only comprise the base of sea-ice ecosystems, but also seed populations of extensive ice-edge blooms during ice melt. Ice algae must rapidly acclimate to dynamic light environments, from the low light under sea ice to high light within open waters. Recently, iron (Fe) deficiency has been reported for diatoms in eastern Antarctic pack ice. Low Fe availability reduces photosynthetic plasticity, leading to reduced ice-algal primary production. We developed a low-Fe ice tank to manipulate Fe availability in sea ice. Over 20 days in the ice tank, the Antarctic ice diatom Fragilariopsis cylindrus was incubated in artificial low-Fe sea ice ([total Fe] = 20 nM) in high light (HL) and low light (LL) conditions. Melted ice was also exposed to intense light to simulate light conditions typical for melting ice in situ. When diatoms were frozen in, the maximum photochemical quantum efficiency of photosystem II (PSII), Fv/Fm, was suppressed by freezing stress. However, the diatoms maintained photosynthetic capability throughout the ice periods with a stable Fv/Fm value and increased photoprotection through non-photochemical quenching (NPQ) via photoprotective xanthophyll cycling (XC) and increased photoprotective carotenoid levels compared to pre-freeze-up. Photoprotection was more pronounced in the HL treatment due to greater light stress. However, the functional absorption cross section of PSII, σPSII, in F. cylindrus consistently increased after freezing, especially in the LL treatment (σPSII > 10 nm2 PSII–1). Our study is the first to report such a large σPSII in ice diatoms at low Fe conditions. When the melted sea ice was exposed to high light, Fv/Fm was suppressed. NPQ and XC were slightly upregulated, but not to values normally observed when Fe is not limiting, which indicates reduced photosynthetic flexibility to adapt to environmental changes during ice melt under low Fe conditions. Although ice algae can optimize ... |
format |
Article in Journal/Newspaper |
author |
Kazuhiro Yoshida Andreas Seger Matthew Corkill Petra Heil Kristen Karsh Andrew McMinn Koji Suzuki |
author_facet |
Kazuhiro Yoshida Andreas Seger Matthew Corkill Petra Heil Kristen Karsh Andrew McMinn Koji Suzuki |
author_sort |
Kazuhiro Yoshida |
title |
Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank |
title_short |
Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank |
title_full |
Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank |
title_fullStr |
Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank |
title_full_unstemmed |
Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank |
title_sort |
low fe availability for photosynthesis of sea-ice algae: ex situ incubation of the ice diatom fragilariopsis cylindrus in low-fe sea ice using an ice tank |
publisher |
Frontiers Media S.A. |
publishDate |
2021 |
url |
https://doi.org/10.3389/fmars.2021.632087 https://doaj.org/article/ca33d01668844a298610d2c79f9549b0 |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic ice algae Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic ice algae Sea ice Southern Ocean |
op_source |
Frontiers in Marine Science, Vol 8 (2021) |
op_relation |
https://www.frontiersin.org/articles/10.3389/fmars.2021.632087/full https://doaj.org/toc/2296-7745 2296-7745 doi:10.3389/fmars.2021.632087 https://doaj.org/article/ca33d01668844a298610d2c79f9549b0 |
op_doi |
https://doi.org/10.3389/fmars.2021.632087 |
container_title |
Frontiers in Marine Science |
container_volume |
8 |
_version_ |
1766253201486512128 |