Seasonal and spatial distribution of bacterioplankton in a fluvial-lagunar system of a tropical region: Density, biomass, cellular volume and morphologic variation

Abstract

The temporal and spatial fluctuations of Bacterioplankton in a fluvial-lagunar system of a tropical region (Pitimbu River and Jiqui Lake, RN) were studied during the dry and the rainy periods. The bacterial abundance varied from 2.67 to 5.1 Cells107mL-1 and did not show a typical temporal variation, presenting only small oscillations between the rainy and the dry periods. The bacterial biomass varied from 123 μgC L -1 to 269 μgC L-1 in the sampling sites and the average cellular volume varied from 0.12 to 0.54μm3, showing a predominance of the rods. The temperature showed a positive correlation with the cellular volume of the rods (R=0.55; p=0.02) and vibrio (R=0.53; p=0.03). Significant spatial differences of biomass (Mann Whitney: p=0.01) and cellular volume of the morphotypes (Mann Whitney: p=0.003) were found between the sampling sites. The strong positive correlations of the water temperature and oxygen with bacterioplankton showed a probable high bacterial activity in this system.