ABSTRACT
The bacterioplanktonic abundance, biomass, and production within a tropical lagoon (Cabiúnas, Brazil) and two temperate lakes (Stechlin and Dagow, Germany) were compared. Bacterial abundance and production were significantly different among the three water bodies. The lowest bacterial production ( 0.8mug C l-1 d-1) was observed in the tropical Cabiúnas Lagoon despite its higher mean temperature and dissolved organic carbon concentration. Highest bacterioplankton abundance ( 2.6 x 10(9) cells l-1) and production ( 68.5mug C l-1 d-1) were measured in eutrophic Lake Dagow. In oligotrophic Lake Stechlin, the lowest bacterial biomass ( 48.05mug C l-1) was observed because of lower bacterial biovolume ( 0.248mum³) and lower bacterial abundance. Bacterial populations in the temperate lakes show higher activity (production/biomass ratio) than in the tropical lagoon. The meaning of isotopic dilution and leucine incorporation by non-bacterial micro-organisms were evaluated in the oligotrophic temperate system. Leucine uptake by non-bacterial micro-organisms did not have significant influence on bacterial production