Published: Jun 11, 2013 1:00 PM EDT
Updated: Jun 11, 2013 9:53 PM EDT

SANIBEL, Fla.- The City of Sanibel continues to monitor an algae bloom spotted in the Gulf of Mexico yesterday. Biologists have identified it as a single-celled blue-green algae called Trichodesmium erythraeum.

The Natural Resources Director with the City of Sanibel says reports from the Florida Fish and Wildlife Conservation Research Institute show the bloom is not harmful to humans, but can pose respiratory irritation.

Officials encourage beachgoers to steer clear of the algae, should they see it. 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.

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:

http://myfwc.com/research/redtide/archive/historical-events/trichodesmium-fl-2004/