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Iron and zinc enrichments in the northeastern subarctic Pacific: ligand production and zinc availability in response to phytoplankton growth

Iron and zinc enrichments in the northeastern subarctic Pacific: ligand production and zinc availability in response to phytoplankton growth
Iron and zinc enrichments in the northeastern subarctic Pacific: ligand production and zinc availability in response to phytoplankton growth
Iron- and zinc-enrichment experiments were carried out at Ocean Station Papa in the subarctic North Pacific. In iron-enriched treatments AI phytoplankton chlorophyll a (Chl a) increased 20-fold (9.7 mu g L-1) above the concentration on day zero. No stimulation of Chl a production or nitrate drawdown was observed on addition of zinc alone compared to the control. In the iron-enriched treatment, bioavailable zinc concentration decreased to 0.2 pmol L-1 lower than that which is known in culture experiments to limit some phytoplankton growth. Theoretical analyses suggest that this zinc concentration would cause diffusion-limited growth of large diatom cells present at the end of the incubation. Direct measurements of zinc-binding ligands indicate that the natural microbial planktonic assemblages have the ability to respond rapidly to conditions of high dissolved zinc concentrations. Rapid ligand production may be a mechanism by which certain phytoplankton reduce zinc toxicity or for maintaining zinc concentrations in the upper water column. Zinc-binding ligands were observed to be both produced and removed on the timescale of 1 d. We suggest that these zinc-binding ligands are produced to assist assimilation, particularly under iron-enriched conditions when concentrations of bioavailable zinc were extremely low, thereby alleviating the effects of zinc limitation.
0024-3590
1427-1437
Lohan, M.C.
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Crawford, D.W.
1625e56b-d0c8-4c45-b519-094d0e928a63
Purdie, D.A.
18820b32-185a-467a-8019-01f245191cd8
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c
Lohan, M.C.
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Crawford, D.W.
1625e56b-d0c8-4c45-b519-094d0e928a63
Purdie, D.A.
18820b32-185a-467a-8019-01f245191cd8
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c

Lohan, M.C., Crawford, D.W., Purdie, D.A. and Statham, P.J. (2005) Iron and zinc enrichments in the northeastern subarctic Pacific: ligand production and zinc availability in response to phytoplankton growth. Limnology and Oceanography, 50 (5), 1427-1437. (doi:10.4319/lo.2005.50.5.1427).

Record type: Article

Abstract

Iron- and zinc-enrichment experiments were carried out at Ocean Station Papa in the subarctic North Pacific. In iron-enriched treatments AI phytoplankton chlorophyll a (Chl a) increased 20-fold (9.7 mu g L-1) above the concentration on day zero. No stimulation of Chl a production or nitrate drawdown was observed on addition of zinc alone compared to the control. In the iron-enriched treatment, bioavailable zinc concentration decreased to 0.2 pmol L-1 lower than that which is known in culture experiments to limit some phytoplankton growth. Theoretical analyses suggest that this zinc concentration would cause diffusion-limited growth of large diatom cells present at the end of the incubation. Direct measurements of zinc-binding ligands indicate that the natural microbial planktonic assemblages have the ability to respond rapidly to conditions of high dissolved zinc concentrations. Rapid ligand production may be a mechanism by which certain phytoplankton reduce zinc toxicity or for maintaining zinc concentrations in the upper water column. Zinc-binding ligands were observed to be both produced and removed on the timescale of 1 d. We suggest that these zinc-binding ligands are produced to assist assimilation, particularly under iron-enriched conditions when concentrations of bioavailable zinc were extremely low, thereby alleviating the effects of zinc limitation.

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More information

Published date: 2005
Additional Information: Not available online until Autumn 2008
Organisations: Marine Biogeochemistry

Identifiers

Local EPrints ID: 17746
URI: http://eprints.soton.ac.uk/id/eprint/17746
ISSN: 0024-3590
PURE UUID: ae4e06e4-93e7-4c29-bc27-e439a7f9af4c
ORCID for M.C. Lohan: ORCID iD orcid.org/0000-0002-5340-3108
ORCID for D.A. Purdie: ORCID iD orcid.org/0000-0001-6672-1722

Catalogue record

Date deposited: 24 Oct 2005
Last modified: 16 Mar 2024 04:13

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Contributors

Author: M.C. Lohan ORCID iD
Author: D.W. Crawford
Author: D.A. Purdie ORCID iD
Author: P.J. Statham

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