Bacterial production in Guanabara Bay (Rio de Janeiro, Brazil) evaluated by 3H-leucine incorporation

The aim of this work was to evaluate the necessary H-3-leucine concentration to estimate bacterial production in Guanabara Bay through saturation curves. A second aim was to collect preliminary data of bacterial production in two distinct sites corresponding to different water qualities: Urea inlet and Governador Island. Saturation curves were made with water samples taken at the main circulation channel of the bay, Paqueta Island, and the two sites mentioned before. The H-3-leucine curves showed similar pattern for all studied areas, indicating the ideal isotope concentration to be 10 nM. Bacterial biomass production ranged from 0.40 to 4.53 mu gC L-1 h(-1) in Urca and from 3.86 to 73.72 mu gC L-1 h(-1) in Governador Island indicating the relationship between nutrients and organic matter supply and bacterial productivity. This work is an important reference for studies on trophodynamics, biogeochemical cycles and modelling in Guanabara Bay.