MICROBIAL COMMMUNITIES (BACTERIOPLANKTON AND PROTOZOOPLANKTON) IN RESERVOIRS OF ABRAZILIAN SEMI-ARID REGION.

Abstract

We studied the seasonal and spatial variations of bacterioplankton and protozooplankton of five reservoirs located in the basin of Piranhas-Assu River, in a semi-arid region in northeast Brazil (Rio Grande do Norte state). The celular density of bacteria and protozoa (ciliates and microflagelates) and the specific composition of the protozooplankton were estimated in samplings carried out during dry and rainy periods, from 2002 through 2004. The bacterial density varied from 2 x 106 to 1,34 x 108cel.mL-1 and was higher in the sampling sites next to the entrance of the rivers that originate the reservoirs. The protozooplankton density was higher on the last samples taken during the rainy period and varied from 13 to 1482org.mL-1. The prelimanary analysis of the data indicated high bacterial densities and indicators species of protozoa were find in places with high organic pollution, alerting for the necessity of continuous monitoring of the Basin where the studied reservoirs are located.