Desferrioxamine B (DFOB, a terrestrial bacterial siderophore) has been used in experiments on waters from iron‐replete areas of the oceans to manipulate the levels of iron available to the biota. Addition of DFOB complexes the available iron (III) and has been suggested to render this complexed iron unavailable to marine microorganisms. We have identified a marine bacterium belonging to the genus Vibrio that produces the sider...