Atmospherically transported dust from the Saharan desert provides pulses of biologically important nutrients, including iron, to ocean surface waters. The biological response to these ephemeral events is not fully known, especially among the heterotrophic microbial community. Here we use the well-characterized Vibrio genus as a model for heterotrophic bacterial response. We demonstrate that Saharan dust nutrients, deposited in tropical marine waters, can promote Vibrio bloom formation and suggest that dust-associated iron is an important driver of Vibrio population dynamics.