By Janet Raloff
For years, scientists have puzzled over the episodic emergence of toxic algal blooms in Florida’s coastal waters. One type, referred to as red tides, takes its name from the rosy cast that the algae impart to the surface of affected waters. A new study now establishes that the periodic arrival of plumes of iron-rich African soil can jump-start these red tides.
Huge storms often scoop up soil and propel it long distances, even across oceans (see “Dust, the Thermostat” in this issue: Dust, the Thermostat). Parched regions of Saharan Africa serve as a major source of such dust plumes crossing the Atlantic. Indeed, much of the red soil common throughout the Caribbean arrived there on winds from Africa.