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Abstract:
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The composition and variability of heterotrophic bacteria along the shelf sediments of south west coast of India and
its relationship with the sediment biogeochemistry was investigated. The bacterial abundance ranged from 1.12 x
103 – 1.88 x 106 CFU g-1 dry wt. of sediment. The population showed significant positive correlation with silt (r =
0.529, p< 0.05), organic carbon (OC) (r = 0.679, p< 0.05), total nitrogen (TN) (r = 0.638, p< 0.05), total protein
(TPRT) (r = 0.615, p< 0.05) and total carbohydrate (TCHO) (r = 0.675, p< 0.05) and significant negative
correlation with sand (r = -0.488, p< 0.05). Community was mainly composed of Bacillus, Alteromonas, Vibrio,
Coryneforms, Micrococcus, Planococcus, Staphylococcus, Moraxella, Alcaligenes, Enterobacteriaceae,
Pseudomonas, Acinetobacter, Flavobacterium and Aeromonas. BIOENV analysis explained the best possible
environmental parameters i.e., carbohydrate, total nitrogen, temperature, pH and sand at 50m depth and organic
matter, BPC, protein, lipid and temperature at 200m depth controlling the distribution pattern of heterotrophic
bacterial population in shelf sediments. The Principal Component Analysis (PCA) of the environmental variables
showed that the first and second principal component accounted for 65% and 30.6% of the data variance
respectively. Canonical Correspondence Analysis (CCA) revealed a strong correspondence between bacterial
distribution and environmental variables in the study area. Moreover, non-metric MDS (Multidimensional Scaling)
analysis demarcated the northern and southern latitudes of the study area based on the bioavailable organic matter |