The Madagascar Bloom – a serendipitous study
The Madagascar Bloom – a serendipitous study
The late austral summer (February-April) phytoplankton bloom that occurs east of Madagascar exhibits significant interannual variability and at its largest extent covers ~1% of the world’s ocean surface area. The bloom raises many intriguing questions about how it begins, is sustained, propagates to the east, exports carbon and ends. It has been observed and studied using satellite ocean color observations, but the lack of in situ data makes it difficult to address these questions. Here we describe observations that were made serendipitously on a cruise in February 2005. These show clearly for the first time the simultaneous existence of a deep chlorophyll maximum at ~70-110 m depths (seen in SeaSoar fluorimeter data) and a surface chlorophyll signature (seen in SeaWiFS satellite ocean color data). The observations also show the modulation of biological signature at the surface by the eddy field, but not of the deep chlorophyll maximum. Trichodesmium dominates the bloom nearer to Madagascar, while the diatom Rhizosolenia clevei (and its symbiont Richelia intracellularis) dominates further from the island. The surface bloom seen in the SeaWiFS data is confined to the shallow (~30 m) mixed layer. It is hypothesized that the interannual variability in bloom intensity may be due to variations in coastal upwelling and thus the supply of iron, which is a micronutrient that can limit diazotroph growth.
Madagascar, bloom, phytoplankton, SeaWiFS, eddies
14-25
Srokosz, M.A.
1e0442ce-679f-43f2-8fe4-9a0f0174d483
Quartly, G.D.
3d1e4e87-f001-4d18-b95f-9bca4db6ff9d
January 2013
Srokosz, M.A.
1e0442ce-679f-43f2-8fe4-9a0f0174d483
Quartly, G.D.
3d1e4e87-f001-4d18-b95f-9bca4db6ff9d
Srokosz, M.A. and Quartly, G.D.
(2013)
The Madagascar Bloom – a serendipitous study.
Journal of Geophysical Research, 118 (1), .
(doi:10.1029/2012JC008339).
Abstract
The late austral summer (February-April) phytoplankton bloom that occurs east of Madagascar exhibits significant interannual variability and at its largest extent covers ~1% of the world’s ocean surface area. The bloom raises many intriguing questions about how it begins, is sustained, propagates to the east, exports carbon and ends. It has been observed and studied using satellite ocean color observations, but the lack of in situ data makes it difficult to address these questions. Here we describe observations that were made serendipitously on a cruise in February 2005. These show clearly for the first time the simultaneous existence of a deep chlorophyll maximum at ~70-110 m depths (seen in SeaSoar fluorimeter data) and a surface chlorophyll signature (seen in SeaWiFS satellite ocean color data). The observations also show the modulation of biological signature at the surface by the eddy field, but not of the deep chlorophyll maximum. Trichodesmium dominates the bloom nearer to Madagascar, while the diatom Rhizosolenia clevei (and its symbiont Richelia intracellularis) dominates further from the island. The surface bloom seen in the SeaWiFS data is confined to the shallow (~30 m) mixed layer. It is hypothesized that the interannual variability in bloom intensity may be due to variations in coastal upwelling and thus the supply of iron, which is a micronutrient that can limit diazotroph growth.
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Published date: January 2013
Keywords:
Madagascar, bloom, phytoplankton, SeaWiFS, eddies
Organisations:
Marine Physics and Ocean Climate
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Local EPrints ID: 346711
URI: http://eprints.soton.ac.uk/id/eprint/346711
ISSN: 0148-0227
PURE UUID: 76e4a5be-e029-4fd4-9774-99e17920b36d
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Date deposited: 07 Jan 2013 14:42
Last modified: 14 Mar 2024 12:40
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Author:
M.A. Srokosz
Author:
G.D. Quartly
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