Iron, a critical element for living organisms, can be hard to hard to come by in open marine waters-except each summer, when atmospherically transported dust from north Africa’s Sahara Desert provides pulses of biologically important nutrients, including iron, to the tropical marine waters of the Caribbean and southeastern U.S.
In a study published today in the Proceedings of the National Academy of Sciences, researchers from the University of Georgia found that Vibrio bacteria respond rapidly to this influx of iron-rich Saharan dust, leading to large blooms of the potentially harmful bacteria in ocean surface water.
[Photo: Dr. Erin Lipp (left) and Dr. Jason Westrich]
Vibrio bacteria, common to ocean waters worldwide, are probably best known for their ability to cause serious illness in humans and other marine organisms. These bacteria are also characterized by their ability to reproduce rapidly and respond to newly available resources.
“Part of what makes these normal marine bacteria also potentially pathogenic is their ability to grow quickly when conditions are favorable, whether in a host or in the environment,” said study co-author Dr. Erin Lipp, a professor of environmental health science in the UGA College of Public Health.
“While we are interested in how the population dynamics of Vibrio might cause disease, for this study we wanted to use Vibrio’s opportunistic behavior as a model for how bacteria could exploit the availability of new nutrients and, in particular, iron delivered in dust.”
Vibrio cases are increasing at a higher rate than many other bacterial pathogens in the U.S., which could be due in part to Vibrio bacteria populations in coastal waters expanding with rising sea surface temperatures, Dr. Lipp said. Adding to this, increased desertification in the Sahara could lead to more dust events and, therefore, more potentially harmful Vibrio blooms.
“Knowing the connection between Saharan dust and Vibrio population blooms is significant from the perspective that we are able to track these dust events using satellites in real time,” Dr. Westrich said. “This allows some predictive power to understand when there is an increased risk for Vibrio infection in humans and other marine organisms.”