For the first time in months, all of Southwest Florida appears relatively free of toxic levels of the red tide algae.
The Florida Fish and Wildlife Conservation Commission posts on myfwc.com a map with the results of the last eight days of water sampling for concentrations of the toxic algae throughout the the state.
The red tide algae, Karinia brevis, is natural to the Gulf in concentrations less than 1,000 cells per liter of water. With the exception of one sample, no water samples posted Wednesday from Naples to Tampa turned up toxic levels of the algae.
The one exception on the map, taken 15 miles offshore from Marco Island, turned up a low concentration, 10,000 to 100,000 cells per water liter. When bloom concentrations reach 100,000 cells per liter, people can start coughing and suffer respiratory irritations, as well as triggering the deaths of fish and other marine life.
FWC Research Institute spokeswoman Michelle Kerr, however, expressed a word of caution Wednesday.
"Since there are medium concentrations detected in some samples, the bloom is still considered ongoing at this time," she said.
Nine days ago, two water samples taken in the mouth of the Myakka River — one at Trout Creek and a second taken in El Jobean at the State Road 776 bridges — did show higher concentrations, more than 10,000 cells per liter of water.
The red tide algae is a marine species that does not survive in fresh water, but seeing red tide creeping up that far in Charlotte Harbor is not necessarily surprising.
"It is not uncommon to observe (red tide algae) in salinities down to 20 (parts per 1,000)," FWC Research Institute spokeswoman Michelle Kerr said in an email to the Sun. The Gulf of Mexico sees salinity levels of 36 parts per 1,000.
"It is possible that there is an increase in salinity in the area due to reduction in river outflows (Myakka and Peace rivers), due to below-average rainfall in the area right now," Kerr said. "Tidal influences can also play a role, depending on tidal cycles and intensity."
The Myakka River hasn't been nourished with rainfall like years past, which can lead to higher salinity levels in the harbor.
According to wiilyweather.com, which draws data from the National Oceanic and Atmospheric Administration, the total rainfall in November was 0 inches, whereas the monthly average rainfall for the Myakka is 1.5 inches of rain.