Red tide is back in Southwest Florida’s Gulf waters.

Fish kills have been reported along Collier County beaches on Marco Island and respiratory irritation is possible for beachgoers from Bonita Beach to Cape Romano—more than 30 miles of shore line.

Florida Gulf Coast University Professor and Director of the Coastal Watershed Institute, Dr. Mike Parsons, said his and other organizations have been out sampling the water to try and track where it’s originating and what’s feeding it.

“This is kind of an interesting time to see to really kind of look at if people are having an influence on red tide, is this just- so far - a natural red tide and will we be influencing it this year,” Dr. Parsons said.

According to the Florida Fish and Wildlife Conservation Commission, Karenia brevis, the organism responsible for red tide, is showing up in medium to high numbers along Collier County and low to very low in southern Lee County.

Charlotte, Sarasota and Manatee counties are reporting only background levels of red tide, which means no effects are anticipated at this time.