NAPLES — A red tide could be creeping closer to Collier County this week as a response team of scientists and water samplers gears up to keep track of its path.
Satellite images show a 15-mile-wide swath of water with elevated levels of chlorophyll, a possible indication of a red tide bloom, centered offshore of Charlotte Harbor. It stretches from inshore Sarasota County to some 40 miles offshore of northern Collier County.
Red tide is a bloom of microscopic algae that releases a toxin that can kill marine life and cause respiratory irritation, especially among people with chronic conditions such as asthma and emphysema. No health warnings have been issued in Collier County.
Dead fish have been washing ashore in Sarasota County this week, and fish kills have been reported 10 to 20 miles west of Lee County. Water samples from Gasparilla Pass showed high levels of red tide earlier this week.
So far, though, water samples from coastal Collier haven't shown a red tide has rolled in, but that could change depending on winds and currents.
"You guys seem to still be in the clear," said Jennifer Wolny, a red tide biologist at the Florida Fish and Wildlife Conservation Commission's research laboratory in St. Peterburg.
The Department of Agriculture and Consumer Services, which monitors the health of shellfish beds in south Lee County, and Sarasota-based Mote Marine Laboratory were on the water Thursday taking samples as far south as offshore of Vanderbilt Beach.
Mote and the University of South Florida plan to drop underwater robotic gliders into the Gulf of Mexico today to try to determine the extent of the red tide. Monitors are putting together a "more concerted sampling effort" for coming weeks, Wolny said.
September and October are peak months for red tides in Southwest Florida, though scientists still are trying to pinpoint just how the blooms are triggered.
It's likely a combination of changing wind patterns pushing red tide closer to shore, nutrient-laden runoff fueling the inshore blooms and the red tide algae's natural growth cycle, scientists theorize.
"It's sort of like making chili," said Barbara Kirkpatrick, a senior scientist at Mote.
The appearance of red tide in some Southwest Florida waters comes almost exactly a year after another red tide popped up that eventually became the worst bloom since 2006 off Collier's coast.
The 2011 bloom lingered for months, causing periodic problems with dead fish on the beach and in Estero Bay in southern Lee County and prompting complaints from beachgoers about watery eyes and scratchy throats.