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Blue-green algae health warnings diminishing on Caloosahatchee

Many locals expected heavy blue-green algae outbreak in Southwest Florida this summer like this one pictured above in the St. John's River recently
Florida Department of Environmental Protection
Many locals expected a heavy blue-green algae outbreak in Southwest Florida this summer like this one pictured above in the St. Johns River recently

The Florida Department of Health in Lee County canceled five health warnings due to harmful algal blooms in the Caloosahatchee River

The Florida Department of Health in Lee County canceled five health warnings due to harmful algal blooms in the Caloosahatchee River and its watershed.

The cancellations are a reversal of the one-after-another trend of red tide or blue-green algae outbreaks in Southwest Florida that began days after Hurricane Ian slammed into Lee County in late September 2023
Right after Hurricane Ian, land-based nutrients like fertilizers were washed into the Gulf of Mexico by the hurricane’s massive volume of rainwater and storm surge. The first red tides were found offshore of Sarasota County, and as the months went by, dozens more blooms of the toxins, often airborne, were detected throughout.

The red tides dissipated as the Gulf got warmer heading into this summer.

Then more than a dozen masses of blue-green algae — another harmful algae bloom — were discovered by testing in the Caloosahatchee River from June through August, which prompted state officials to issue health advisories from the upper Caloosahatchee River to the lower, warning of the presence of the toxic organism throughout.

Skin rashes, gastrointestinal turmoil, and respiratory distress are potential outcomes of contact with algae-filled water. Blue-green algae have also killed family pets who played in infected areas, as well as entire flocks of birds who landed in lakes covered in the slimy, green algae.

In addition to health effects, harmful algae blooms cause significant economic losses when they take hold, keeping tourists and residents alike away from saltwater beaches due to the acrid odors and dead fish lining the shore that are the hallmark of red tide, and the rotten-egg smell and slimy blue-green algae in freshwater lakes and rivers.

Despite the five canceled health warnings, several more remain, and not in places that can so easily be defined because many of the piles of algae float around with the winds and tides.

“It is important that the public exercise caution and good judgment,” the health department said in a press release. “Blue-green algae blooms can move around or subside and then reappear when conditions are favorable again. Residents and visitors are advised to avoid contact with the water if blooms are observed.”

Hurricane Irma, a powerful Category 5 storm five years before Ian, also caused significant damage across the state. The storm's impact on the environment and coastal areas was substantial, highlighting the need for resilient infrastructure and climate adaptation measures.

Like Ian, Irma kicked up nutrients from the bottom of Lake Okeechobee as well as the surrounding watershed of the lake and the Caloosahatchee River, leading to the blue-green algae outbreaks on the Caloosahatchee: thick, green, slimy and smelly, that resulted in day trips and entire vacations ruined.

More blue-green algae?

Hurricane season is in its most dangerous weeks, and despite the billions of dollars spent on the restorations of the Everglades and the recent cancellations of the five blue-green algae outbreaks in the river, the history behind the harmful algae blooms have yet to be undone.

More than a century ago, the Army Corps of Engineers linked the Caloosahatchee River to Lake Okeechobee by digging a canal through the river’s swampy headwaters west of the lake.

These days, that waterway is the most common one the Army Corps uses to release water from Lake Okeechobee when levels are high.

The problem is that the lake water is hopelessly polluted with nitrogen and phosphorus that’s flowed into it from more than a century of fertilizer use by industrial-sized agriculture operations and people wanting the grass to grow around their homes.

In 2018, heavy releases of lake water into the river are believed responsible for the massive blue-green algae outbreak that fouled the greater Caloosahatchee River estuary all summer. That summer was also the first after a big Hurricane Irma churned up the lake bottom in 2017.

Also called cyanobacteria, blue-green algae has already bloomed in the lake this spring and many are still worried that conditions are shaping up for a repeat of 2018 in the river this summer if another hurricane like Irma and Ian comes this way.

A boat crosses a previous bloom of blue-green algae on Lake Okeechobee
Pedro Portal of the Miami Herald via WLRN
A boat crosses a previous bloom of blue-green algae on Lake Okeechobee

Government agreement

Red tide was detected at every beach in Sarasota County soon after Hurricane Ian made landfall near Fort Myers in late September. At one point, the Florida Fish and Wildlife Conservation Commission found the red tide organism, Karenia brevis, in nearly 100 samples throughout Southwest Florida.

Florida Department of Health officials in Manatee, Sarasota, Charlotte, Lee, and Collier counties began issuing health alerts daily warning of the real and present danger to humans and animals.

Blue-green algae are minuscule organisms that inhabit freshwater bodies across the nation. These organisms, a natural part of aquatic ecosystems, hold the potential for beauty but also for peril when they overstay their ecological welcome and become slimy, smelly leftovers.

Once again, facets of climate change are exacerbating red tide and blue-green algae in Southwest Florida.

Nutrient pollution, larger and more frequent hurricanes, sea-level rise, and overall changes to the ocean are becoming recognized even by federal agencies once skeptical of the connection.

Environmental reporting for WGCU is funded in part by VoLo Foundation, a nonprofit with a mission to accelerate change and global impact by supporting science-based climate solutions, enhancing education, and improving health. 

Copyright 2023 WGCU. To see more, visit WGCU.

Tom Bayles