High numbers of Trichodesmium and diazotrophic diatoms
in the southwest Indian Ocean
High numbers of Trichodesmium and diazotrophic diatoms
in the southwest Indian Ocean
We observed high cell numbers of large (>50?m) nitrogen-fixing phytoplankton to the south and to the east of Madagascar in February 2005. The distribution of the diazotrophic taxa we found was markedly different: Trichodesmium was most abundant (500-1000 trichomes L-1) in the waters at the southern tip of Madagascar, while diazotrophic diatoms (125-500 cells L-1) were found to be abundant to the southeast of Madagascar. From these cell numbers, using literature values of nitrogen-fixation per cell, we estimate potential rates of nitrogen-fixation for Trichodesmium (south of Madagascar) of 1-5 mmol N m-2 d-1 and for diazotrophic diatoms (east of Madagascar) of 0.4-2.4 mmol N m-2 d-1. These cell-based estimates highlight the potential for significant nitrogen-fixation in the southwest Indian Ocean. High numbers of diazotrophic diatoms in subtropical waters to the east of Madagascar may have important implications for the biogeochemistry of the austral phytoplankton blooms that occur in this area.
L15610-[4pp]
Poulton, Alex J.
14bf64a7-d617-4913-b882-e8495543e717
Stinchcombe, Mark C.
433dd398-15f7-4730-9f1e-992d65bec70b
Quartly, Graham D.
3d1e4e87-f001-4d18-b95f-9bca4db6ff9d
8 August 2009
Poulton, Alex J.
14bf64a7-d617-4913-b882-e8495543e717
Stinchcombe, Mark C.
433dd398-15f7-4730-9f1e-992d65bec70b
Quartly, Graham D.
3d1e4e87-f001-4d18-b95f-9bca4db6ff9d
Poulton, Alex J., Stinchcombe, Mark C. and Quartly, Graham D.
(2009)
High numbers of Trichodesmium and diazotrophic diatoms
in the southwest Indian Ocean.
Geophysical Research Letters, 36, .
(doi:10.1029/2009GL039719).
Abstract
We observed high cell numbers of large (>50?m) nitrogen-fixing phytoplankton to the south and to the east of Madagascar in February 2005. The distribution of the diazotrophic taxa we found was markedly different: Trichodesmium was most abundant (500-1000 trichomes L-1) in the waters at the southern tip of Madagascar, while diazotrophic diatoms (125-500 cells L-1) were found to be abundant to the southeast of Madagascar. From these cell numbers, using literature values of nitrogen-fixation per cell, we estimate potential rates of nitrogen-fixation for Trichodesmium (south of Madagascar) of 1-5 mmol N m-2 d-1 and for diazotrophic diatoms (east of Madagascar) of 0.4-2.4 mmol N m-2 d-1. These cell-based estimates highlight the potential for significant nitrogen-fixation in the southwest Indian Ocean. High numbers of diazotrophic diatoms in subtropical waters to the east of Madagascar may have important implications for the biogeochemistry of the austral phytoplankton blooms that occur in this area.
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Submitted date: 13 May 2009
Published date: 8 August 2009
Organisations:
National Oceanography Centre,Southampton
Identifiers
Local EPrints ID: 66227
URI: http://eprints.soton.ac.uk/id/eprint/66227
ISSN: 0094-8276
PURE UUID: 50a7e073-0318-4f0f-b667-670f3758a575
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Date deposited: 18 May 2009
Last modified: 13 Mar 2024 18:11
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Author:
Alex J. Poulton
Author:
Mark C. Stinchcombe
Author:
Graham D. Quartly
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