Stay in the know about wildlife, water quality, and ecosystems on Sanibel and Captiva Islands and in Southwest Florida

Red Tide Counts Continue to Go Down

April 5, 2023

On March 31, Lee County reported three water samples containing bloom concentrations of Karenia brevis, marking a significant decrease from what we were seeing in February.

“The lower counts continue the same trend that we saw in March of fewer samples with bloom concentrations,” said SCCF Research & Policy Associate Leah Reidenbach. “Water clarity around the island is good and there have been no reports of respiratory issues or fish kills on Sanibel beaches.” 

Although the lack of rain is causing drought conditions, Lake Okeechobee is at 14.44 ft, continuing to drop steadily, and approaching the top of the ecological envelope. 

“While this is good news, the damage to the submerged aquatic vegetation while the lake was too high will require several seasons within optimal environmental conditions in order to fully recover its ecosystem functions,” said Reidenbach. 

The Army Corps of Engineers is still delivering a 7-day average of 2,000 cubic feet per second (cfs) to S-79, which flows into Caloosahatchee estuary and 500 cfs to S-80, which flows into the St. Lucie estuary. These flow levels are within the RECOVER 2020 optimal flow envelopes for each estuary (750 – 2,100 cfs and 150 – 1,400 cfs, respectively). 

“One of the reasons the Caloosahatchee receives a greater volume of water than the St. Lucie estuary is because the RECOVER performance measure for salinity and the ecology of each system requires different flows,” she explained.

The Caloosahatchee River and estuary is larger than the St. Lucie estuary, and the Caloosahatchee needs more freshwater in order to maintain a salinity gradient that supports a diversity of wildlife including submerged aquatic vegetation, seagrass, and oysters. The St. Lucie estuary is smaller and requires less water to maintain a salinity gradient. 

“Overall, less water is entering the lake from the north and more water is flowing out of the lake to the northern estuaries, but not enough water is being sent south to the Everglades where it is really needed because the Water Conservation Areas are currently too full,” she added.



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