An initial fall bloom occurred in September and October followed by a second bloom beginning in late December. This second bloom has persisted and moved southward through the month of February. In late January fish kills were reported near Key West. Low to medium concentrations of G. breve in the westernmost Florida Keys have been detected in early February. Since mid-February the sampling program has concentrated around the Marco Island area in Collier County where the bloom continues to persist into April.
Numbers refer to the number of sites sampled.