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Phytoplankton carbon fixation, chlorophyll-biomass and diagnostic pigments in the Atlantic Ocean

Phytoplankton carbon fixation, chlorophyll-biomass and diagnostic pigments in the Atlantic Ocean
Phytoplankton carbon fixation, chlorophyll-biomass and diagnostic pigments in the Atlantic Ocean
We have made daily measurements of phytoplankton pigments, size-fractionated (<2 and >2-?m) carbon fixation and chlorophyll-a concentration during four Atlantic Meridional Transect (AMT) cruises in 2003–04. Surface rates of carbon fixation ranged from <0.2-mmol C m?3 d?1 in the subtropical gyres to 0.2–0.5-mmol C m?3 d?1 in the tropical equatorial Atlantic. Significant intercruise variability was restricted to the subtropical gyres, with higher chlorophyll-a concentrations and carbon fixation in the subsurface chlorophyll maximum during spring in either hemisphere. In surface waters, although picoplankton (<2-?m) represented the dominant fraction in terms of both carbon fixation (50–70%) and chlorophyll-a (80–90%), nanoplankton (>2-?m) contributions to total carbon fixation (30–50%) were higher than to total chlorophyll-a (10–20%). However, in the subsurface chlorophyll maximum picoplankton dominated both carbon fixation (70–90%) and chlorophyll-a (70–90%). Thus, in surface waters chlorophyll-normalised carbon fixation was 2–3 times higher for nanoplankton and differences in picoplankton and nanoplankton carbon to chlorophyll-a ratios may lead to either higher or similar growth rates. These low chlorophyll-normalised carbon fixation rates for picoplankton may also reflect losses of fixed carbon (cell leakage or respiration), decreases in photosynthetic efficiency, grazing losses during the incubations, or some combination of all these. Comparison of nitrate concentrations in the subsurface chlorophyll maximum with estimates of those required to support the observed rates of carbon fixation (assuming Redfield stoichiometry) indicate that primary production in the chlorophyll maximum may be light rather than nutrient limited.

phytoplankton, carbon fixation, picoplankton, nanoplankton, chlorophyll-a, Atlantic Meridional Transect
0967-0645
1593-1610
Poulton, A.J.
14bf64a7-d617-4913-b882-e8495543e717
Holligan, P.M.
4c1d9d64-dfa7-49bf-9e15-37f891d59b7c
Hickman, A.
a99786c6-65e6-48c8-8b58-0d3b5608be92
Kim, Y.N.
07f5787d-bec4-4104-86ef-236c1a9fca59
Adey, T.R.
21d6bd04-fdd8-4ad6-8805-60416f32b2c3
Stinchcombe, M.C.
433dd398-15f7-4730-9f1e-992d65bec70b
Holeton, C.
fef385fd-f83a-4f25-9c1e-e73e163316ec
Root, S.
1a630f90-487f-41b0-b85f-c3d11be362f3
Woodward, E.M.S.
3ac3b98f-78c7-4b43-acf9-bba3253752b5
Poulton, A.J.
14bf64a7-d617-4913-b882-e8495543e717
Holligan, P.M.
4c1d9d64-dfa7-49bf-9e15-37f891d59b7c
Hickman, A.
a99786c6-65e6-48c8-8b58-0d3b5608be92
Kim, Y.N.
07f5787d-bec4-4104-86ef-236c1a9fca59
Adey, T.R.
21d6bd04-fdd8-4ad6-8805-60416f32b2c3
Stinchcombe, M.C.
433dd398-15f7-4730-9f1e-992d65bec70b
Holeton, C.
fef385fd-f83a-4f25-9c1e-e73e163316ec
Root, S.
1a630f90-487f-41b0-b85f-c3d11be362f3
Woodward, E.M.S.
3ac3b98f-78c7-4b43-acf9-bba3253752b5

Poulton, A.J., Holligan, P.M., Hickman, A., Kim, Y.N., Adey, T.R., Stinchcombe, M.C., Holeton, C., Root, S. and Woodward, E.M.S. (2006) Phytoplankton carbon fixation, chlorophyll-biomass and diagnostic pigments in the Atlantic Ocean. Deep Sea Research Part II: Topical Studies in Oceanography, 53 (14-16), 1593-1610. (doi:10.1016/j.dsr2.2006.05.007).

Record type: Article

Abstract

We have made daily measurements of phytoplankton pigments, size-fractionated (<2 and >2-?m) carbon fixation and chlorophyll-a concentration during four Atlantic Meridional Transect (AMT) cruises in 2003–04. Surface rates of carbon fixation ranged from <0.2-mmol C m?3 d?1 in the subtropical gyres to 0.2–0.5-mmol C m?3 d?1 in the tropical equatorial Atlantic. Significant intercruise variability was restricted to the subtropical gyres, with higher chlorophyll-a concentrations and carbon fixation in the subsurface chlorophyll maximum during spring in either hemisphere. In surface waters, although picoplankton (<2-?m) represented the dominant fraction in terms of both carbon fixation (50–70%) and chlorophyll-a (80–90%), nanoplankton (>2-?m) contributions to total carbon fixation (30–50%) were higher than to total chlorophyll-a (10–20%). However, in the subsurface chlorophyll maximum picoplankton dominated both carbon fixation (70–90%) and chlorophyll-a (70–90%). Thus, in surface waters chlorophyll-normalised carbon fixation was 2–3 times higher for nanoplankton and differences in picoplankton and nanoplankton carbon to chlorophyll-a ratios may lead to either higher or similar growth rates. These low chlorophyll-normalised carbon fixation rates for picoplankton may also reflect losses of fixed carbon (cell leakage or respiration), decreases in photosynthetic efficiency, grazing losses during the incubations, or some combination of all these. Comparison of nitrate concentrations in the subsurface chlorophyll maximum with estimates of those required to support the observed rates of carbon fixation (assuming Redfield stoichiometry) indicate that primary production in the chlorophyll maximum may be light rather than nutrient limited.

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More information

Published date: 2006
Keywords: phytoplankton, carbon fixation, picoplankton, nanoplankton, chlorophyll-a, Atlantic Meridional Transect

Identifiers

Local EPrints ID: 43985
URI: http://eprints.soton.ac.uk/id/eprint/43985
ISSN: 0967-0645
PURE UUID: ad84efae-178b-43d3-ad20-6cde8884173b
ORCID for A. Hickman: ORCID iD orcid.org/0000-0002-2774-3934

Catalogue record

Date deposited: 06 Feb 2007
Last modified: 16 Mar 2024 04:11

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Contributors

Author: A.J. Poulton
Author: P.M. Holligan
Author: A. Hickman ORCID iD
Author: Y.N. Kim
Author: T.R. Adey
Author: M.C. Stinchcombe
Author: C. Holeton
Author: S. Root
Author: E.M.S. Woodward

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