Trichodesmium is a blue-green algae that blooms every year in the Gulf of Mexico. Vonna Keomanyvong/Naples Daily News
A patchy algae bloom that can look like sawdust or murky water has washed ashore in spots from Marco Island to North Naples this week, beach monitors reported.
The algae is not the kind that causes red tide.
Rather, it's Trichodesmium, a blue-green algae that blooms every year in the Gulf of Mexico. It last came ashore in Collier County in May 2013 and May 2014.
The bloom, which is not known to make people sick, comes and goes from different parts off the beach, moved around by winds and waves, monitors reported.
Winds out of the southwest Thursday seemed to have pushed pieces of the bloom northward along the Collier shoreline to the Seagate Beach south of Clam Pass, county monitor Rhonda Watkins said.
"It's just very patchy," she said.
Naples Harbormaster Roger Jacobsen said he stood Thursday on the Naples Pier and could see only crystal-clear water both north and south of the landmark.
"We're OK on Naples beaches right now," he said.
Every summer, iron-rich dust blown from the Sahara Desert in Africa settles in the Gulf and triggers the blooms, which convert nitrogen gas into nutrients for use by other marine organisms, including red tide.
As the bloom decays, it can give off an odor — some liken it to freshly cut hay — and can turn green, pink and white, according to the Florida Fish and Wildlife Conservation Commission.
Fish kills are possible if the bloom washes into back bays or canals, where it can suck oxygen out of poorly flushed waters.