Macroalgae provide important habitats for microorganisms, with surfaces that are rich in nutrients and a microbial niche for isolation of different bacterial groups. In this study, we evaluated the production of enzymes (amylases, lipases, cellulases and agarases) and siderophores by strains isolated from the macroalga Ulva lactuca growing in the Santa Marta region of the Colombian Caribbean Sea. We taxonomically identified a subset of the bacteria and tested 207 bacterial isolates. Of these, 25 (12%) and 121 (58%) produced agarases and siderophores, respectively. Out of the isolated bacteria with amylolytic (97), cellulolytic (118) and lipolytic (26) activity, 31 (32%), 78 (66%) and 4 (15%) strains, respectively, produced a zone of clearance >1.5 cm, indicating substantial activity. Enzymatic activities and siderophore production were statistically different between years of sampling, and principal component analysis showed grouping for samples from the same year. These activities and production were recorded in bacterial strains belonging to the genera Vibrio, Pseudomonas and Bacillus. The results show that marine bacterial cultures isolated from the macroalga U. lactuca are a source of enzymes and siderophores that may have potential for biotechnological and industrial processes.