Recently, Southwest Florida water quality studies undertaken by Sanibel Captiva Conservation Foundation found select locations containing karenia brevis, the organism that can bloom into red tide. According to a statement from SCCF, these findings represent “a typical fall bloom of medium concentration, which has occurred 23 times in October over the past 25 years, somewhere between Pinellas County to roughly Cape Romano (according to FWC Fish and Wildlife Research Institute data}.”
As for any concern of red tide blooms, Sanibel Captiva Conservation Foundation repeats that “our scientists are not sounding red tide alarms beyond a typical fall bloom of medium concentration (which has occurred, again, 23 times in the past 25 years).”
In addition, according to the most recent 8-day study by Florida Fish & Wildlife (through October 17), only 5 of 15 locations as indicated on this map show any levels of karenia brevis — 1 near South Seas (low), 2 on the eastern end of Sanibel (moderate) and two in San Carlos Bay (moderate). The remaining gray dots represent ZERO evidence of the organism.
The bottom line: evidence of karenia brevis in Southwest Florida waters in the fall is a common, almost-always-annual occurrence. It is not a predictor that conditions will change, and travelers to Southwest Florida should be aware of this fact.