Our coronavirus coverage is free for the first 24 hours. Find the latest information at Please consider subscribing or donating.

  1. News

Clay may combat Florida's Red Tide, but opposition ended experiments here 15 years ago

With Red Tide creeping up the Southwest Florida coast and into the Panhandle, Gov. Rick Scott on Thursday announced an international research partnership to determine if the toxic algae bloom can be quelled by clay.

The effort is bringing together Woods Hole Oceanographic Institution, the University of South Florida, Mote Marine Laboratory and the Florida Department of Environmental Protection. Scott also called for the state wildlife commission to set up the Florida Center for Red Tide Research.

Coming just days after Scott was heckled at a campaign stop by protesters who dubbed him "Red Tide Rick," the new action plan drew criticism from the Sierra Club, which called the proposed center "nothing more than a self-serving publicity stunt."

Resorting to clay to treat the algae is not new. Prior experiments with it in Florida ran into strong public opposition, according to a Don Anderson, a senior scientist with Woods Hole who was involved in those studies 15 years ago.

"We made a naive mistake," Anderson said. Surprised by the blowback, "we gave up."

RELATED: Your Red Tide questions answered.

Anderson, who is part of the new Florida initiative, said clay has been used for decades to combat harmful algae blooms in other countries, particularly South Korea and China. Scientists in Japan first detailed experiments with clay in 1989 but dropped it because of the potential cost.

The concept is simple: Find something heavy that sticks to the algae in the bloom and weighs it down like anchors. Dragged to the ocean bottom, away from sunlight and the nutrients it feeds on, the algae dies.

But the clay had to be just the right type. The wrong one might irritate the algae rather than kill it.

In the early 2000s, Woods Hole launched experiments to test what would be the right clay to use against Red Tide. The one the Woods Hole scientists chose was phosphatic clay — a residue of Florida's controversial phosphate industry. It's usually dumped into settling ponds as waste.

"We saw great promise in it," Anderson said. "It was free, it was available close by and it was extremely effective."

The scientists commenced experiments in Sarasota Bay, with help from Mote, spraying the clay in small areas to see what impact it would have. But then, Anderson said, "we ran into a buzz saw of environmental opposition. People did not want this dumped into the ocean."

RELATED: When will Red Tide go away?

There were two problems, he said. One was that the phosphate industry has what he called "a lot of baggage" in terms of public opposition. The other is that to be effective, Woods Hole would have to spray a tremendous amount of clay into the water, because a lot was just dirt, Anderson said.

Experiments showed the toxic algae wasn't the only thing affected by the clay. One experiment found "significant negative impacts of clay on filtration" on filter-feeding bivalves such as scallops, clams and other crustaceans. The cure seemed as bad as the disease.

Faced with so much opposition, Woods Hole and Mote ended their experiments, he said, but Chinese scientists pushed on. In recent years they have developed what he called "a super-pure clay" that they combine with a polymer that gives the particles a positive charge.

The algae cells are negatively charged, so they're attracted to the clay, he explained. That means using far less clay than the prior experiments did, he said, and as a result "a lot of the environmental impacts are just gone."

There may still be ill effects on some species, he said, but the key question is "whether the impacts are less than the impacts of Red Tide."

Anderson said he hopes to get a new round of pilot tests launched by the end of the year, perhaps again in Sarasota. He's so confident of the results, he wants to test the use of clay on the toxic blue-green algae that's in Lake Okeechobee and its connecting estuaries, too.

Gil McRae, the head of the state's Fish and Wildlife Research Institute in St. Petersburg, says he'd like to see the testing begin a lot sooner than that.

"We want to get out there while this Red Tide bloom is out there," McRae said. However, he added, "You want to be sure that your treatment doesn't do more damage than the Red Tide does."

The cost of the project is unknown at this point, he said, although his staff would be discussing that with their collaborators Friday.

Anderson predicted the project will be expensive, since it involves bringing in Chinese scientists with supplies of their new clay material to test. They may be delayed in getting to Florida, he said, because their region was recently smacked by a typhoon.

In calling for a new center for Red Tide research, Gov. Scott told the wildlife commissioners to ask the Legislature for more money, without noting that a Politico analysis found that funding for such research had dropped under his administration and that of his predecessor, Charlie Crist.

And he encouraged the wildlife commissioners — all of whom he appointed — to reconvene a toxic algae bloom task force that was established in 1997 but hasn't met for at least a decade.

The ongoing Red Tide bloom, which was first detected in November, has become the worst in a decade, killing tons of fish, manatees, dolphins and sea turtles and sickening scores of sea birds, as well as ruining the economies of beach towns along more than 100 miles of the state's coast.

While no one knows what causes a Red Tide bloom to begin offshore, scientists say that the bloom can be prolonged by pollution from leaky septic tanks, sewage dumping, fertilizer in stormwater runoff, and nutrients coming out of the Mississippi River, as well as dust from the Sahara desert. The Sierra Club contended that rather than more research on Red Tide, what Florida needs is tighter government controls over the sources of pollution flowing into the water.

Contact Craig Pittman at Follow @craigtimes.