BACTERIAL (FREE LIVING AND PARTICLE BOUND) CELL- SIZE IN THE SURFACE WATERS OF RIVER CAUVERY AND ITS UPSTREAM TRIBUTARIES IN KARNATAKA STATE, INDIA

Abstract

Cell-size here refers to mean length, as only the lengths of bacterial cells were measured in this study. Cell breadths were not measured, hence calculation of biovolume and biomass was not possible. In this study, the mean cell-lengths of heterotrophic bacterioplankton as well as their relation with environmental (water-quality) variables were analyzed for two years in the main river Cauvery and its four important upstream tributaries from February 2000 to January 2002. The initial hypothesis that all the five water courses have similar bacterial mean cell-lengths was rejected, because mean cell-lengths of free living and particle bound planktonic bacteria was more and was also significantly different in the river Lakshmanatheertha, when compared to the other four water courses studied. Season-wise grouped data revealed that, the mean cell-length of free-living bacteria was significantly less in winter season as compared to rainy and summer seasons during the second year of study only in the river Lakshmanatheertha. A correlation (r) analysis between the mean cell-lengths of heterotrophic bacteria and environmental (water-quality) variables revealed significant relations. Also with the help of regression analysis (r) the effect of some important environmental variables on the mean cell-length of heterotrophic bacteria has been discussed in the light of recent investigations in the field of fresh water microbial ecology.