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Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica

Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica
Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica
The bioavailability of iron influences the distribution, biomass and productivity of phytoplankton in the Ross Sea, one of the most productive regions in the Southern Ocean. We mapped the spatial and temporal extent and severity of iron-limitation of the native phytoplankton assemblage using long- (>24 h) and short-term (24 h) iron-addition experiments along with physiological and molecular characterisations during a cruise to the Ross Sea in December-February 2012. Phytoplankton increased their photosynthetic efficiency in response to iron addition, suggesting proximal iron limitation throughout most of the Ross Sea during summer. Molecular and physiological data further indicate that as nitrate is removed from the surface ocean the phytoplankton community transitions to one displaying an iron-efficient photosynthetic strategy characterised by an increase in the size of photosystem II (PSII) photochemical cross section (?PSII) and a decrease in the chlorophyll-normalised PSII abundance. These results suggest that phytoplankton with the ability to reduce their photosynthetic iron requirements are selected as the growing season progresses, which may drive the well-documented progression from Phaeocystis antarctica- assemblages to diatom-dominated phytoplankton. Such a shift in the assemblage-level photosynthetic strategy potentially mediates further drawdown of nitrate following the development of iron deficient conditions in the Ross Sea.
Iron, Phytoplankton, Photosynthetic proteins, Photosystem II, Nutrient limitation, Ross Sea
0924-7963
87-96
Ryan-Keogh, Thomas J.
86e4ee72-2e27-4f45-a579-6edb67de4ac4
DeLizo, Liza M.
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Smith, Walker O.
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Sedwick, Peter N.
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McGillicuddy, Dennis J.
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Moore, C. Mark
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Bibby, Thomas S.
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Ryan-Keogh, Thomas J.
86e4ee72-2e27-4f45-a579-6edb67de4ac4
DeLizo, Liza M.
7f7509d5-0d90-4389-b41f-61464546f2bb
Smith, Walker O.
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Sedwick, Peter N.
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McGillicuddy, Dennis J.
52d5f309-a5c6-41c5-a491-5ae242f96617
Moore, C. Mark
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Bibby, Thomas S.
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Ryan-Keogh, Thomas J., DeLizo, Liza M., Smith, Walker O., Sedwick, Peter N., McGillicuddy, Dennis J., Moore, C. Mark and Bibby, Thomas S. (2017) Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica. Journal of Marine Systems, 166, 87-96. (doi:10.1016/j.jmarsys.2016.08.014).

Record type: Article

Abstract

The bioavailability of iron influences the distribution, biomass and productivity of phytoplankton in the Ross Sea, one of the most productive regions in the Southern Ocean. We mapped the spatial and temporal extent and severity of iron-limitation of the native phytoplankton assemblage using long- (>24 h) and short-term (24 h) iron-addition experiments along with physiological and molecular characterisations during a cruise to the Ross Sea in December-February 2012. Phytoplankton increased their photosynthetic efficiency in response to iron addition, suggesting proximal iron limitation throughout most of the Ross Sea during summer. Molecular and physiological data further indicate that as nitrate is removed from the surface ocean the phytoplankton community transitions to one displaying an iron-efficient photosynthetic strategy characterised by an increase in the size of photosystem II (PSII) photochemical cross section (?PSII) and a decrease in the chlorophyll-normalised PSII abundance. These results suggest that phytoplankton with the ability to reduce their photosynthetic iron requirements are selected as the growing season progresses, which may drive the well-documented progression from Phaeocystis antarctica- assemblages to diatom-dominated phytoplankton. Such a shift in the assemblage-level photosynthetic strategy potentially mediates further drawdown of nitrate following the development of iron deficient conditions in the Ross Sea.

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Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica.pdf - Accepted Manuscript
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Accepted/In Press date: 28 August 2016
Published date: 1 February 2017
Keywords: Iron, Phytoplankton, Photosynthetic proteins, Photosystem II, Nutrient limitation, Ross Sea
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 400893
URI: http://eprints.soton.ac.uk/id/eprint/400893
ISSN: 0924-7963
PURE UUID: c178a7d0-0d21-4559-8734-a6cb97f3acfa
ORCID for C. Mark Moore: ORCID iD orcid.org/0000-0002-9541-6046

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Date deposited: 29 Sep 2016 09:21
Last modified: 28 Apr 2022 06:18

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Contributors

Author: Thomas J. Ryan-Keogh
Author: Liza M. DeLizo
Author: Walker O. Smith
Author: Peter N. Sedwick
Author: Dennis J. McGillicuddy
Author: C. Mark Moore ORCID iD
Author: Thomas S. Bibby

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