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Relevance of bacterioplankton abundance and production in the oligotrophic equatorial Indian Ocean

DRS at CSIR-National Institute of Oceanography

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Title Relevance of bacterioplankton abundance and production in the oligotrophic equatorial Indian Ocean
 
Creator Fernandes, V.
Rodrigues, V.
Ramaiah, N.
Paul, J.T.
 
Subject Indian Ocean
Bacterioplankton
primary production
phytoplankton
euphotic zone
oligotrophic
 
Description Bacterioplankton abundance and production, chlorophyll a (Chl a) concentrations and primary production (PP) were measured from the equatorial Indian Ocean (EIO) during northeast (NEM), southwest (SWM) and spring intermonsoon (SpIM) seasons from 1 degrees N to 5 degrees S along 83 degrees E. The average bacterial abundance was 0.52 plus or minus 0.29, 0.62 plus or minus 0.33 and 0.46 plus or minus 0.19 (x 10 sup(8) cells l sup(?1)), respectively during NEM, SWM and SpIM in the top 100 m. In the deep waters (200 m and below), the bacterial counts averaged approx. 0.35 plus or minus 0.14 x 10 sup(8) cells l sup(-1) in SWM and 0.39 plus or minus 0.16 x 10 sup(8) cells l sup(-1) in SpIM. The 0?120 m column integrated bacterial production (BP) ranged from 19 to 115 and from 10 to 51 mg C m sup(-2) d sup(-1) during NEM and SWM, respectively. Compared with many open ocean locations, bacterial abundance and production in this region are lower. The bacterial carbon production, however, is notably higher than that of phytoplankton PP (BP:PP ratio 102% in SWM and 188% in NEM). With perpetually low PP (NEM: 20, SWM: 18 and SpIM: 12 mg C m sup(-2) d sup(-1)) and Chl a concentration (NEM: 16.5, SWM: 15.0 and SpIM: 20.9 mg m sup(-2)), the observed bacterial abundance and production are pivotal in the trophodynamics of the EIO. Efficient assimilation and mineralization of available organics by bacteria in the euphotic zone might serve a dual role in the ultra-oligotrophic regions including EIO. Thus, bacteria probably sustain microheterotrophs (micro- and meso-zooplankton) through microbial loop. Further, rapid mineralization by bacteria will make essential nutrients available to autotrophs
 
Date 2009-01-20T08:31:54Z
2009-01-20T08:31:54Z
2008
 
Type Journal Article
 
Identifier Aquatic Ecology, vol.42(4); 511-519
http://drs.nio.org/drs/handle/2264/2115
 
Language en
 
Rights Copyright [2008]. 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 Springer