Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern Ocean
The availability of iron (Fe) to marine microbial communities is enhanced through complexation by ligands. In Fe limited environments, measuring the distribution and identifying the likely sources of ligands is therefore central to understanding the drivers of marine productivity. Antarctic coastal...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-08-01
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| Series: | Frontiers in Marine Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmars.2022.948772/full |
| _version_ | 1818172863053561856 |
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| author | Abigail J.R. Smith Talitha Nelson Lavenia Ratnarajah Cristina Genovese Karen Westwood Karen Westwood Thomas M. Holmes Matthew Corkill Ashley T. Townsend Elanor Bell Kathrin Wuttig Delphine Lannuzel |
| author_facet | Abigail J.R. Smith Talitha Nelson Lavenia Ratnarajah Cristina Genovese Karen Westwood Karen Westwood Thomas M. Holmes Matthew Corkill Ashley T. Townsend Elanor Bell Kathrin Wuttig Delphine Lannuzel |
| author_sort | Abigail J.R. Smith |
| collection | DOAJ |
| description | The availability of iron (Fe) to marine microbial communities is enhanced through complexation by ligands. In Fe limited environments, measuring the distribution and identifying the likely sources of ligands is therefore central to understanding the drivers of marine productivity. Antarctic coastal marine environments support highly productive ecosystems and are influenced by numerous sources of ligands, the magnitude of which varies both spatially and seasonally. Using competitive ligand exchange adsorptive cathodic stripping voltammetry (CLE-AdCSV) with 2-(2-thiazolylazo)-p-cresol (TAC) as a competing artificial ligand, this study investigates Fe-binding ligands (FeL) across the continental shelf break in the Mertz Glacier Region, East Antarctica (64 - 67°S; 138 - 154°E) during austral summer of 2019. The average FeL concentration was 0.86 ± 0.5 nM Eq Fe, with strong conditional stability constants (Log KFeL) averaging 23.1 ± 1.0. The strongest binding ligands were observed in modified circumpolar deep water (CDW), thought to be linked to bacterial Fe remineralisation and potential siderophore release. High proportions of excess unbound ligands (L’) were observed in surface waters, as a result of phytoplankton Fe uptake in the mixed layer and euphotic zone. However, FeL and L’ concentrations were greater at depth, suggesting ligands were supplied with dissolved Fe from upwelled CDW and particle remineralisation in benthic nepheloid layers over the shelf. Recent sea-ice melt appeared to support bacterial production in areas where Fe and ligands were exhausted. This study is included within our newly compiled Southern Ocean Ligand (SOLt) Collection, a database of publicly available Fe-binding ligand surveys performed south of 50°S. A review of the SOLt Collection brings attention to the paucity of ligand data collected along the East Antarctic coast and the difficulties in pinpointing sources of Fe and ligands in coastal environments. Elucidating poorly understood ligand sources is essential to predicting future Fe availability for microbial populations under rapid environmental change. |
| first_indexed | 2024-12-11T19:19:22Z |
| format | Article |
| id | doaj.art-d058e808399e48ccae37d3ba7700ab76 |
| institution | Directory Open Access Journal |
| issn | 2296-7745 |
| language | English |
| last_indexed | 2024-12-11T19:19:22Z |
| publishDate | 2022-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj.art-d058e808399e48ccae37d3ba7700ab762022-12-22T00:53:35ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452022-08-01910.3389/fmars.2022.948772948772Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern OceanAbigail J.R. Smith0Talitha Nelson1Lavenia Ratnarajah2Cristina Genovese3Karen Westwood4Karen Westwood5Thomas M. Holmes6Matthew Corkill7Ashley T. Townsend8Elanor Bell9Kathrin Wuttig10Delphine Lannuzel11Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, AustraliaInstitute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, AustraliaDepartment of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, United KingdomDepartment of Géosciences, Environnement et Societé, Université Libre de Bruxelles, Bruxelles, BelgiumAustralian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS, AustraliaAustralian Antarctic Program Partnership, University of Tasmania, Hobart, TAS, AustraliaAustralian Antarctic Program Partnership, University of Tasmania, Hobart, TAS, AustraliaInstitute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, AustraliaCentral Science Laboratory, University of Tasmania, Hobart, TAS, AustraliaAustralian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS, AustraliaAntarctic Climate and Ecosystems Cooperative Research Centre, Hobart, TAS, AustraliaInstitute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, AustraliaThe availability of iron (Fe) to marine microbial communities is enhanced through complexation by ligands. In Fe limited environments, measuring the distribution and identifying the likely sources of ligands is therefore central to understanding the drivers of marine productivity. Antarctic coastal marine environments support highly productive ecosystems and are influenced by numerous sources of ligands, the magnitude of which varies both spatially and seasonally. Using competitive ligand exchange adsorptive cathodic stripping voltammetry (CLE-AdCSV) with 2-(2-thiazolylazo)-p-cresol (TAC) as a competing artificial ligand, this study investigates Fe-binding ligands (FeL) across the continental shelf break in the Mertz Glacier Region, East Antarctica (64 - 67°S; 138 - 154°E) during austral summer of 2019. The average FeL concentration was 0.86 ± 0.5 nM Eq Fe, with strong conditional stability constants (Log KFeL) averaging 23.1 ± 1.0. The strongest binding ligands were observed in modified circumpolar deep water (CDW), thought to be linked to bacterial Fe remineralisation and potential siderophore release. High proportions of excess unbound ligands (L’) were observed in surface waters, as a result of phytoplankton Fe uptake in the mixed layer and euphotic zone. However, FeL and L’ concentrations were greater at depth, suggesting ligands were supplied with dissolved Fe from upwelled CDW and particle remineralisation in benthic nepheloid layers over the shelf. Recent sea-ice melt appeared to support bacterial production in areas where Fe and ligands were exhausted. This study is included within our newly compiled Southern Ocean Ligand (SOLt) Collection, a database of publicly available Fe-binding ligand surveys performed south of 50°S. A review of the SOLt Collection brings attention to the paucity of ligand data collected along the East Antarctic coast and the difficulties in pinpointing sources of Fe and ligands in coastal environments. Elucidating poorly understood ligand sources is essential to predicting future Fe availability for microbial populations under rapid environmental change.https://www.frontiersin.org/articles/10.3389/fmars.2022.948772/fullFe availabilitymicrobial productivitybenthic nepheloid layersSOLt collectioncomplexation |
| spellingShingle | Abigail J.R. Smith Talitha Nelson Lavenia Ratnarajah Cristina Genovese Karen Westwood Karen Westwood Thomas M. Holmes Matthew Corkill Ashley T. Townsend Elanor Bell Kathrin Wuttig Delphine Lannuzel Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern Ocean Frontiers in Marine Science Fe availability microbial productivity benthic nepheloid layers SOLt collection complexation |
| title | Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern Ocean |
| title_full | Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern Ocean |
| title_fullStr | Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern Ocean |
| title_full_unstemmed | Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern Ocean |
| title_short | Identifying potential sources of iron-binding ligands in coastal Antarctic environments and the wider Southern Ocean |
| title_sort | identifying potential sources of iron binding ligands in coastal antarctic environments and the wider southern ocean |
| topic | Fe availability microbial productivity benthic nepheloid layers SOLt collection complexation |
| url | https://www.frontiersin.org/articles/10.3389/fmars.2022.948772/full |
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