Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy
In the Subantarctic sector of the Southern Ocean, vertical entrainment of iron (Fe) triggers the seasonal productivity cycle but diminishing physical supply during the spring to summer transition forces microbial assemblages to rapidly acclimate. Here, we tested how phytoplankton and bacteria within...
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ftdoajarticles:oai:doaj.org/article:1c86edf2cfc3480a84e6e309ed23e9eb 2023-05-15T18:24:55+02:00 Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy Marion Fourquez Robert F. Strzepek Michael J. Ellwood Christel Hassler Damien Cabanes Sam Eggins Imojen Pearce Stacy Deppeler Thomas W. Trull Philip W. Boyd Matthieu Bressac 2022-08-01T00:00:00Z https://doi.org/10.3390/microorganisms10081655 https://doaj.org/article/1c86edf2cfc3480a84e6e309ed23e9eb EN eng MDPI AG https://www.mdpi.com/2076-2607/10/8/1655 https://doaj.org/toc/2076-2607 doi:10.3390/microorganisms10081655 2076-2607 https://doaj.org/article/1c86edf2cfc3480a84e6e309ed23e9eb Microorganisms, Vol 10, Iss 1655, p 1655 (2022) iron regeneration particles Southern Ocean eddies vertical supply Subantarctic Biology (General) QH301-705.5 article 2022 ftdoajarticles https://doi.org/10.3390/microorganisms10081655 2022-12-30T22:18:28Z In the Subantarctic sector of the Southern Ocean, vertical entrainment of iron (Fe) triggers the seasonal productivity cycle but diminishing physical supply during the spring to summer transition forces microbial assemblages to rapidly acclimate. Here, we tested how phytoplankton and bacteria within an isolated eddy respond to different dissolved Fe (DFe)/ligand inputs. We used three treatments: one that mimicked the entrainment of new DFe (Fe-NEW), another in which DFe was supplied from bacterial regeneration of particles (Fe-REG), and a control with no addition of DFe (Fe-NO). After 6 days, 3.5 (Fe-NO, Fe-NEW) to 5-fold (Fe-REG) increases in Chlorophyll a were observed. These responses of the phytoplankton community were best explained by the differences between the treatments in the amount of DFe recycled during the incubation (Fe-REG, 15% recycled c.f. 40% Fe-NEW, 60% Fe-NO). This additional recycling was more likely mediated by bacteria. By day 6, bacterial production was comparable between Fe-NO and Fe-NEW but was approximately two-fold higher in Fe-REG. A preferential response of phytoplankton (haptophyte-dominated) relative to high nucleic acid (HNA) bacteria was also found in the Fe-REG treatment while the relative proportion of diatoms increased faster in the Fe-NEW and Fe-NO treatments. Comparisons between light and dark incubations further confirmed the competition between picophytoplankton and HNA for DFe. Overall, our results demonstrate great versatility by microorganisms to use different Fe sources that results in highly efficient Fe recycling within surface waters. This study also encourages future research to further investigate the interactions between functional groups of microbes (e.g. HNA and cyanobacteria) to better constraint modeling in Fe and carbon biogeochemical cycles. Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Microorganisms 10 8 1655 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
iron regeneration particles Southern Ocean eddies vertical supply Subantarctic Biology (General) QH301-705.5 |
spellingShingle |
iron regeneration particles Southern Ocean eddies vertical supply Subantarctic Biology (General) QH301-705.5 Marion Fourquez Robert F. Strzepek Michael J. Ellwood Christel Hassler Damien Cabanes Sam Eggins Imojen Pearce Stacy Deppeler Thomas W. Trull Philip W. Boyd Matthieu Bressac Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy |
topic_facet |
iron regeneration particles Southern Ocean eddies vertical supply Subantarctic Biology (General) QH301-705.5 |
description |
In the Subantarctic sector of the Southern Ocean, vertical entrainment of iron (Fe) triggers the seasonal productivity cycle but diminishing physical supply during the spring to summer transition forces microbial assemblages to rapidly acclimate. Here, we tested how phytoplankton and bacteria within an isolated eddy respond to different dissolved Fe (DFe)/ligand inputs. We used three treatments: one that mimicked the entrainment of new DFe (Fe-NEW), another in which DFe was supplied from bacterial regeneration of particles (Fe-REG), and a control with no addition of DFe (Fe-NO). After 6 days, 3.5 (Fe-NO, Fe-NEW) to 5-fold (Fe-REG) increases in Chlorophyll a were observed. These responses of the phytoplankton community were best explained by the differences between the treatments in the amount of DFe recycled during the incubation (Fe-REG, 15% recycled c.f. 40% Fe-NEW, 60% Fe-NO). This additional recycling was more likely mediated by bacteria. By day 6, bacterial production was comparable between Fe-NO and Fe-NEW but was approximately two-fold higher in Fe-REG. A preferential response of phytoplankton (haptophyte-dominated) relative to high nucleic acid (HNA) bacteria was also found in the Fe-REG treatment while the relative proportion of diatoms increased faster in the Fe-NEW and Fe-NO treatments. Comparisons between light and dark incubations further confirmed the competition between picophytoplankton and HNA for DFe. Overall, our results demonstrate great versatility by microorganisms to use different Fe sources that results in highly efficient Fe recycling within surface waters. This study also encourages future research to further investigate the interactions between functional groups of microbes (e.g. HNA and cyanobacteria) to better constraint modeling in Fe and carbon biogeochemical cycles. |
format |
Article in Journal/Newspaper |
author |
Marion Fourquez Robert F. Strzepek Michael J. Ellwood Christel Hassler Damien Cabanes Sam Eggins Imojen Pearce Stacy Deppeler Thomas W. Trull Philip W. Boyd Matthieu Bressac |
author_facet |
Marion Fourquez Robert F. Strzepek Michael J. Ellwood Christel Hassler Damien Cabanes Sam Eggins Imojen Pearce Stacy Deppeler Thomas W. Trull Philip W. Boyd Matthieu Bressac |
author_sort |
Marion Fourquez |
title |
Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy |
title_short |
Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy |
title_full |
Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy |
title_fullStr |
Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy |
title_full_unstemmed |
Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy |
title_sort |
phytoplankton responses to bacterially regenerated iron in a southern ocean eddy |
publisher |
MDPI AG |
publishDate |
2022 |
url |
https://doi.org/10.3390/microorganisms10081655 https://doaj.org/article/1c86edf2cfc3480a84e6e309ed23e9eb |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Microorganisms, Vol 10, Iss 1655, p 1655 (2022) |
op_relation |
https://www.mdpi.com/2076-2607/10/8/1655 https://doaj.org/toc/2076-2607 doi:10.3390/microorganisms10081655 2076-2607 https://doaj.org/article/1c86edf2cfc3480a84e6e309ed23e9eb |
op_doi |
https://doi.org/10.3390/microorganisms10081655 |
container_title |
Microorganisms |
container_volume |
10 |
container_issue |
8 |
container_start_page |
1655 |
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1766205958968573952 |