As the long, hot summer continues, the National Oceanic and Atmospheric Administration continues to track cyanobacteria concentrations in Lake Okeechobee. The computer-generated image is derived from data using satellite imagery capturing spectrums of light not visible to the human eye. Cloud cover and wind can affect the satellite data.
The image from Aug. 9 “is cloud-free and the wind speed was low (1-2 mph) during the time of image acquisition. Therefore, it provides a better estimate of bloom coverage since the last couple of weeks,” explained Dr. Sachi Mishra, of NOAA. The image clearly shows the bloom accumulation and surface scum formation in the northeast quadrant of the lake, Dr. Mishra explained. “Some surface scum is also visible in the southern part of the lake. We estimate the bloom to be covering 250 square miles or about 45 percent of the lake surface area.”
Different colors in the image indicate concentrations of cyanobacteria. The areas in red have the highest concentration and are most likely to have visible algae on the surface.
Cyanobacteria (also called blue-green algae, although it is not technically algae) can rise and fall in the water. The imagery indicates areas of cyanobacteria concentrations in the water column. It can be in the water and not be visible on the surface.
The imagery cannot determine the species of cyanobacteria present and cannot tell whether or not there are toxins present. There are about a dozen types of cyanobacteria known to be common in Lake Okeechobee, and less than half are capable of producing toxins, according to the University of Florida five-year study of Lake Okeechobee. Even cyanobacteria capable of producing toxins do not always do so.
So far this summer, tests of cyanobacteria blooms on Lake Okeechobee have shown no toxins or very low levels, below the 10 micrograms per liter level considered safe for recreational contact.