<b>Caracterização da assembléia de bactérias nitrificantes pelo método "fluorescent in situ hybridization" (fish) no biofilme e água de larvicultura do camarão-Rosa farfantepenaeus paulensis</b>

Abstract

Between November and December of 2002, one experiment was conducted in the Laboratory of Mariculture of FURG University, Rio Grande – RS/Brazil, during the larviculture of the pink-shrimp Farfantepenaeus paulensis. Artificial substrates were added to the tanks for biofilm formation, and were daily collected and analyzed for chlorophyll a and abundance and composition of bacterial assemblage by the Fluorescent in situ hybridization-FISH technique. The same variables were also analyzed in water samples collected daily besides the concentration of ammonium, nitrite and nitrate. Largest ammonium concentration were measured in the beginning of the larviculture experiment, reaching 413.98 μM and decreasing to 73.92 μM in the following days. A nitrogen mass balance showed that the largest uptake of nitrogen in the tanks resulted from nitrification process (22.3%). Nitrification/denitrification processes showed very important in the nitrogen elimination on larviculture tanks, the 39% of the ammonium was eliminated of the water for this way. The concentration of nitrogen compounds influenced the composition of the bacterial assemblage in the biofilm and water, with the predominance of b- and g-proteobacteria groups, related to the ammonium variation, whereas the a-proteobacteria were related to the nitrite variation.