Blue-Green algae discolors water at Pinellas beaches

A bloom of Trichodesmium, a blue-green algae, is the likely cause of discolored waters along the Pinellas County coast, officials said.

Discolored water along the Pinellas County coast is likely caused by Trichodesmium, a blue-green algae known as “sea sawdust,” the county wrote in a Facebook post Thursday morning [May 18].

County officials have received numerous reports of the discoloration in recent days.

Found worldwide in tropical and subtropical waters, Trichodesmium is “part of a patchy bloom that moves with the winds and currents,” the county said. “The strain found in Florida is not known to be harmful to people or marine life.”

“Based on satellite imagery there may have been a bloom offshore that has now moved onshore,” the city of Treasure Island wrote in a Facebook post. “Beachgoers may notice a slightly musty smell but should know it is not harmful in Florida and common in the Gulf of Mexico.”

When healthy, the blooms appear brown in color, according to the Florida Fish & Wildlife Conservation Commission website. They turn green as they start to decay, pink or red when certain pigments leak out of the cells, and white after they decay.

As they decay, the blooms have a sweet smell similar to freshly cut hay, FWC said.

The agency is investigating and monitoring the blooms, the county said.