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Photosynthetic electron turnover in the tropical and subtropical Atlantic Ocean

Photosynthetic electron turnover in the tropical and subtropical Atlantic Ocean
Photosynthetic electron turnover in the tropical and subtropical Atlantic Ocean
Photosynthetic electron transport directly generates the energy required for carbon fixation and thus underlies the aerobic metabolism of aquatic systems. We determined photosynthetic electron turnover rates, ETRs, from ca. 100 FRR fluorescence water-column profiles throughout the subtropical and tropical Atlantic during six Atlantic Meridional Transect cruises (AMT 6, May–June 1998, to AMT 11, September–October 2000). Each FRR fluorescence profile yielded a water-column ETR-light response from which the maximum electron turnover rate , effective absorption (?PSII) and light saturation parameter (Ek) specific to the concentration of photosystem II reaction centres (RCIIs) were calculated. and Ek increased whilst ?PSII decreased with mixed-layer depth and the daily integrated photosynthetically active photon flux when all provinces were considered together. These trends suggested that variability in maximum ETR can be partly attributed to changes in effective absorption. Independent bio-optical measurements taken during AMT 11 demonstrated that ?PSII variability reflects taxonomic and physiological differences in the phytoplankton communities. and Ek, but not ?PSII, remained correlated with mixed-layer depth and daily integrated photosynthetically active photon flux when data from each oceanic province were considered separately, indicating a decoupling of electron turnover and carbon fixation rates within each province. Comparison of maximum ETRs with 14C-based measurements of Pmax further suggests that light absorption and C fixation are coupled to differing extents for the various oligotrophic Atlantic provinces. We explore the importance of quantifying RCII concentration for determination of ETRs and interpretation of ETR-C fixation coupling.
AMT, subtropical gyres, tropical equatorial, phytoplankton, fast repetition rate fluorometry, photosynthetic electron turnover
0967-0645
1573-1592
Suggett, D.J.
a6ea4076-7f82-477d-8482-8cdbccb9554a
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Maranon, E.
e0e574e3-c100-4772-a003-4213027c818d
Omachi, C.
1d20346a-7bbd-4278-883f-763913f78f54
Varela, R.A.
55cde121-00c5-49f8-8220-c9a41dd7d365
Aiken, J.
afdc4c64-e66d-43e7-a81a-241169a6604d
Holligan, P.M.
4c1d9d64-dfa7-49bf-9e15-37f891d59b7c
Suggett, D.J.
a6ea4076-7f82-477d-8482-8cdbccb9554a
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Maranon, E.
e0e574e3-c100-4772-a003-4213027c818d
Omachi, C.
1d20346a-7bbd-4278-883f-763913f78f54
Varela, R.A.
55cde121-00c5-49f8-8220-c9a41dd7d365
Aiken, J.
afdc4c64-e66d-43e7-a81a-241169a6604d
Holligan, P.M.
4c1d9d64-dfa7-49bf-9e15-37f891d59b7c

Suggett, D.J., Moore, C.M., Maranon, E., Omachi, C., Varela, R.A., Aiken, J. and Holligan, P.M. (2006) Photosynthetic electron turnover in the tropical and subtropical Atlantic Ocean. Deep Sea Research Part II: Topical Studies in Oceanography, 53 (14-16), 1573-1592. (doi:10.1016/j.dsr2.2006.05.014).

Record type: Article

Abstract

Photosynthetic electron transport directly generates the energy required for carbon fixation and thus underlies the aerobic metabolism of aquatic systems. We determined photosynthetic electron turnover rates, ETRs, from ca. 100 FRR fluorescence water-column profiles throughout the subtropical and tropical Atlantic during six Atlantic Meridional Transect cruises (AMT 6, May–June 1998, to AMT 11, September–October 2000). Each FRR fluorescence profile yielded a water-column ETR-light response from which the maximum electron turnover rate , effective absorption (?PSII) and light saturation parameter (Ek) specific to the concentration of photosystem II reaction centres (RCIIs) were calculated. and Ek increased whilst ?PSII decreased with mixed-layer depth and the daily integrated photosynthetically active photon flux when all provinces were considered together. These trends suggested that variability in maximum ETR can be partly attributed to changes in effective absorption. Independent bio-optical measurements taken during AMT 11 demonstrated that ?PSII variability reflects taxonomic and physiological differences in the phytoplankton communities. and Ek, but not ?PSII, remained correlated with mixed-layer depth and daily integrated photosynthetically active photon flux when data from each oceanic province were considered separately, indicating a decoupling of electron turnover and carbon fixation rates within each province. Comparison of maximum ETRs with 14C-based measurements of Pmax further suggests that light absorption and C fixation are coupled to differing extents for the various oligotrophic Atlantic provinces. We explore the importance of quantifying RCII concentration for determination of ETRs and interpretation of ETR-C fixation coupling.

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More information

Published date: 2006
Keywords: AMT, subtropical gyres, tropical equatorial, phytoplankton, fast repetition rate fluorometry, photosynthetic electron turnover

Identifiers

Local EPrints ID: 44126
URI: http://eprints.soton.ac.uk/id/eprint/44126
ISSN: 0967-0645
PURE UUID: 181183fe-3fc1-45c7-afae-9ac8d28b30dd
ORCID for C.M. Moore: ORCID iD orcid.org/0000-0002-9541-6046

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Date deposited: 15 Feb 2007
Last modified: 16 Mar 2024 03:10

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Contributors

Author: D.J. Suggett
Author: C.M. Moore ORCID iD
Author: E. Maranon
Author: C. Omachi
Author: R.A. Varela
Author: J. Aiken
Author: P.M. Holligan

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