Published: Jun 10, 2013 4:55 PM EDT
Updated: Jun 11, 2013 12:44 PM EDT

SANIBEL, Fla.- The City of Sanibel is monitoring an algae bloom along the Gulf of Mexico beaches. A brown colored patch of water in the surf zone along some stretches of Sanibel beaches has been positively identified by biologists as a single-celled blue-green algae called Trichodesmium erythraeum.

Common sense should always be used before swimming in any area with dense concentrations of this or any other algae. Small blooms resemble sawdust floating on the water surface; larger blooms can look like oil slicks or sea foam. Trichodesmium blooms have a unique "sweet" smell when they are breaking down, and large blooms can turn the water red or pink when stressed cells leach out pigments. At various times in their development, blooms can also appear brown, green, or white. The City, in close coordination with the SCCF Marine Lab, Sanibel Sea School, and the Florida Fish and Wildlife Research Institute (FWRI), is carefully monitoring this algae bloom until it dissipates.

According to FWRI, Trichodesmium is found worldwide in tropical and subtropical seas. Blooms are not related to coastal nutrient sources or pollution, but generally form offshore, reaching nearshore waters when pushed in by prevailing winds and tidal currents. Blooms in the Gulf of Mexico tend to occur between May and September, when iron-rich Saharan dust is blown into the atmosphere, transported across the Atlantic Ocean by wind currents, and deposited into the Gulf of Mexico.

Click here for additional information on Trichodesmium in Florida, from FWRI: