Influence of physical and biological processes on the seasonal cycle of biogenic flux in the equatorial Indian Ocean
Seasonal cycle of biogenic fluxes obtained from sediment trap at two locations 5°24' N, 86°46' E (southern Bay of Bengal trap; SBBT) and 3°34' N, 77°46' E (equatorial Indian Ocean trap; EIOT) within the equatorial Indian Ocean (EIO) were examined to understand the factors that co...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2013-11-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/10/7493/2013/bg-10-7493-2013.pdf |
| Summary: | Seasonal cycle of biogenic fluxes obtained from sediment trap at two
locations 5°24' N, 86°46' E (southern Bay of Bengal
trap; SBBT) and 3°34' N, 77°46' E (equatorial Indian
Ocean trap; EIOT) within the equatorial Indian Ocean (EIO) were examined to
understand the factors that control them. The sediment trap data at SBBT was
collected for ten years from November 1987 while that at EIOT was for a one
year period from January 1996. The characteristic of biogenic flux at SBBT
was the strong seasonality with peak flux in August, while lack of
seasonality characterised the flux at EIOT. The high chlorophyll biomass at
the SBBT during the summer monsoon was supported by a combination of processes
such as wind-mixing and advection, both of which supplied new nitrogen to
the upper ocean. In contrast, the elevated chlorophyll at EIOT during summer
monsoon was supported only by wind mixing. High cell counts of phytoplankton
(> 5 μm) at SBBT dominated by diatoms suggest the operation
of classical food web and high carbon export. On the contrary, dominance of
pico-phytoplankton and one-and-a-half time higher magnitude of
micro-zooplankton biomass along with 2-fold lesser meso-zooplankton at EIOT
indicated the importance of microbial loop. The substantial decrease in the
carbon export at EIOT indicated faster remineralization of
photosynthetically produced organic matter. |
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| ISSN: | 1726-4170 1726-4189 |