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Influence of physical processes and freshwater discharge on the seasonality of phytoplankton regime in the Bay of Bengal

DRS at CSIR-National Institute of Oceanography

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Title Influence of physical processes and freshwater discharge on the seasonality of phytoplankton regime in the Bay of Bengal
 
Creator Gomes, H.
Goes, J.I.
Saino, T.
 
Subject phytoplankton
primary production
biomass
seasonality
seasonal variations
nutrients (mineral)
 
Description The seasonality of phytoplankton was examined in the western and northern Bay of Bengal using shipboard data collected during three seasons as well as ocean colour imagery from OCTS and Sea WiFS. Seasonal changes in the hydrography of the bay observed during these seasons gave rise to striking differences in biomass and primary productivity. Heavy fresh water influex from rivers and the resulting vertical stratification impeded vertical transfer of nutrients. Although such a nutrient regime resulted in an oligotrophic environment, chlorophyll a and primary production were substantially enhanced by physical processes that could erode the strong halocline. In March-April (pre-southwest monsoon), the poleward flowing East India Coastal Current brought to the surface, nutrient laden cooler waters that enriched the coastal region, but highest biomass (Chl a, 53 mg m sup(-3)) and productivity (4.5 g C m sup(-2) d sup(-1)) were in the region of an eddylike structure along the coast and in the region between 13 degrees and 16 degrees N lat. Its appearance in satellite images of two consecutive years suggests the structure to be an annual feature. Wind driven coastal upwelling and increased river runoff during the following season, the southwest monsoon (July-August), increased phytoplankton biomass dramatically (92 mg m sup(-2)) but productivity averaged only 0.3 g C m sup(-2) d sup(-1) suggesting light limitation due to intense cloud cover. With a reduction in cloud cover and enhanced irradiance during the following season, the northeast monsoon (January-February), primary production increased especially in the northern part of the bay where phytoplankton appeared to benefit from both improved light conditions and nutrient inputs from estuarine mechanisms and river runoff
 
Date 2009-01-09T09:08:05Z
2009-01-09T09:08:05Z
2000
 
Type Journal Article
 
Identifier Continental Shelf Research, Vol.20; 313-330p.
http://drs.nio.org/drs/handle/2264/1685
 
Language en
 
Rights Copyright [2000]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher Pergamon