Abstract

The knowledge concerning fishpond microorganisms is important considering the aquatic microbial ecology and water quality. In this study, we compared the bacterial communities present in freshwaters of two fish farm ponds from Brazil, one used as water reservoir (P1) and the other with conditions of high nutrient load (P4). The aim of this study was to identify and compare the bacterial population in two fishponds during dry and rainy seasons. The determination of the bacterial population was conducted through sequencing of the 16S rRNA gene. The results show that the bacterial population is different in the ponds and it changes according to the climatic period. Moreover, the diversity of microorganisms in P1 was greater than P4. Proteobacteria predominated in the rainy season in both ponds varied in proportion and classes composition. In the P4 during dry season, Cyanobacteria were predominant due to favorable conditions of environment. This study provides the first local investigation that demonstrates that the bacterial community is differ according to the trophic state of aquatic systems and between rainy and dry seasons, the latter of wich exerted more influence in bacterial communities. It can be suggested that the management in P4 promotes favorable environment for the high density of Cyanobacteria, demonstrating the need for improvements in management.

Key words: 16S rDNA, biodiversity, freshwater, metagenome.