Credit: CC0 Public Domain

Red tide algae showed up in test samples again this week, according to the Florida Fish and Wildlife Conservation Commission's weekly report.

The microscopic red tide-causing phytoplankton known as Karenia brevis tested positive in high concentrations off the shores of Collier County, and medium concentrations in multiple sites of Lee County, the FWC said.

At that level, the FWC said red tide can lead to respiratory irritation for humans, water discoloration and marine life deaths because of the lack of oxygen in the water. More than 40 fish kills associated with red tide algae blooms have been reported since the end of September in Collier and Lee counties with the majority found around Naples, Sanibel and Marco Island waters, FWC showed.

FWC biologists take measurements at hundreds of spots all around the coast every week. Last week, Lee County showed very low to low concentrations of red tide samples.

Red tide samples also emerged in background concentrations in Manatee and Sarasota counties, as well as north Florida in Gulf County.

The east coast of Florida showed no signs of red tide.

Red tide is a natural occurring algae bloom often found in the Gulf of Mexico.

Florida endured a larger than normal red tide bloom in 2018 afflicting its coasts on a massive scale of distance for an unusually long time; leading to thousands of deaths in marine life.

The state spent millions in 2018 on beach cleanups as well as money into research on how to battle red tide.

The state posts its red tide monitor results at myfwc.com/research/redtide/statewide/ with a detailed map of Karenia brevis measurements as well as access to tracking models to predict future movement.

©2019 The Orlando Sentinel (Orlando, Fla.)

Distributed by Tribune Content Agency, LLC.