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Limno-tolerant bacteria govern nitrate concentration in Mandovi estuary, India

DRS at CSIR-National Institute of Oceanography

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Title Limno-tolerant bacteria govern nitrate concentration in Mandovi estuary, India
 
Creator Divya, B.
Fernandes, S.O.
Sheelu, G.
Nair, S.
LokaBharathi, P.A.
Chandramohan, D.
 
Subject Limno-tolerant bacteria
halo-tolerant bacteria
Mandovi estuary
nitrate concentration
 
Description The spatial and temporal abundances of limno-tolerant and halo-tolerant bacteria were investigated in the tide-dominated Mandovi estuary along the west coast of India. These investigations were carried out in relation to various environmental parameters on a monthly basis at three fixed stations for a year. On an annual basis, the estuary showed an average salinity of 28.2, 17.4, and 12.6 at the mouth, midstream and upstream region. Halo-tolerant retrievable count (HTRC) and limno-tolerant retrievable count (LTRC) of bacteria were in the order of 10 sup(6) L sup(-1). Among the environmental parameters, a strong negative relationship between salinity and nitrate (r = 0.806; p less than 0.001) suggested that 64% of the variation could be due to fresh water influence in the estuary. The limno-tolerant retrievable count (LTRC) brought about 23 % variations in nitrate concentration. This influence was maximum during the monsoon (r = 0.522; p less than 0.05) especially in the surface waters (r = 0.624; p less than 0.001) suggesting nitrate reduction by LTRC. Measurements of nitrate reducing activity (NRA) in whole-water samples along the salinity gradient in the estuary also revealed higher reduction rates at lower salinity upstream. This was further confirmed by culture experiments where the limno-tolerant bacteria showed higher NRA than halo-tolerant forms. It is therefore suggested that LTRC is more actively involved in the variation of nitrate that enters the Mandovi estuary particularly during the monsoon.
 
Date 2009-12-21T11:54:41Z
2009-12-21T11:54:41Z
2009
 
Type Journal Article
 
Identifier Estuarine, Coastal and Shelf Science, vol.82(1); 29-34
http://drs.nio.org/drs/handle/2264/3503
 
Language en
 
Rights An edited version of this paper was published by Elsevier. Copyright [2009] Elsevier
 
Publisher Elsevier