It was the summer of dead fish.
For much of coastal Southwest Florida, the summer of 2018 will be remembered for the piles of dead fish that had to be removed from beaches over and over again. A potent and persistent red tide outbreak was to blame as the smell of decay drifted long distances inland.
That decay is what red tide likes. Specifically, it likes ammonia, said Cynthia Heil, Mote Marine Laboratory scientist and director of the new Red Tide Institute.
For years now, scientists have been studying all the food sources of the red tide organism, hoping to find something humans can remove to control or eliminate it. Study after study, however, just identifies more and more nitrogen sources that feed the toxic bloom at different stages and at different locations. Those who study the red tide algae, also known as Karenia brevis, are impressed by its flexibility.
“...(T)hese blooms are the result of a physiologically versatile organism that has adapted to a physically and chemically dynamic environment,” a team of researchers wrote about red tide in a 2014 edition of the scientific journal called Harmful Algae.
Heil was the lead researcher for that paper. Last week, she told an audience of about 600 in Punta Gorda that dead fish may be the biggest food source feeding red tide — bigger than runoff from agricultural fertilizer or septic system. Dead fish don’t start the bloom, but once it gets going, as it did this summer, it starts killing fish, and the decaying fish provide the primary food source, according to Heil’s research.
It’s almost as if red tide is farming its own food, Heil said at Charlotte County’s first Water Quality Summit. Heil spoke with the Sun and was an invited speaker at the Jan. 29 Water Quality Summit at the Charlotte Harbor Event and Conference Center.
Karenia is a microscopic algae. It forms in the Gulf of Mexico periodically for reasons no one is entirely sure of, although theories abound.
After forming offshore, it drifts onshore while emitting an aerosol that is difficult for humans to breath. In the water, it emits a different toxin called brevetoxin. Brevetoxin toxin kills fish, birds, turtles and water mammals. It affects humans if they eat affected shellfish or the guts of fish in red tide.
Whether it can be controlled once it reaches the coast is something scientists do not agree on.
Heil believes it’s time to stop looking for ways to shorten the bloom, and focus on controlling the effects. The fact that dead fish are the biggest food source is one reason Heil favors the mitigation strategy over waiting for pollution controls to take effect.
At the summit and in her research, Heil has warned that eliminating the human sources of nitrogen may not have a dramatic impact on controlling red tide. Human-introduced sources of nitrogen include septic system runoff and fertilizer used in farming or residential yard maintenance.
She and a research team wrote in 2014: “…(E)fforts to reduce potentially controllable nearshore nutrient inputs should be undertaken with the understanding that while they may lead to enhanced water quality, they may not have an immediate impact on the frequency or magnitude of nearshore Karenia brevis blooms.”
Other prominent scientists in the field disagree with this conclusion. They also disagree with the next step that Heil and the institute propose, which is to move toward controlling the effects of red tide rather than controlling its growth.
“The increases we’re seeing in harmful algal blooms are primarily the result of increasing nutrients due to human activities,” said Larry Brand, professor of marine biology at the University of Miami.
He went so far as to accuse Mote Marine of being biased in favor of non-human causes, due to the its dependence on state funds.
“The politicians don’t want to upset the agriculture industry,” he said.
Heil denies her research is affected by any funding source.
Currently, the institute is funded by private philanthropists from Sarasota. Gov. Ron DeSantis, however, is proposing to offer millions of dollars to the institute over five years. The funds would end if the institute produces no results.
Another wetlands engineer and professor, William Mitsch of Florida Gulf Coast University, said dismissing growth control in favor of toxin control is both defeatist and unrealistic.
“That’s the tragedy of having more than one source (of food source for red tide,)” he said. “People just say, ‘Well, we can’t control it,’ and sort of dismiss the problem.”
Both Brand and Mitsch believe the state must restrict all forms of nitrogen runoff, including septic fields and fertilizer. To that list, Mitsch has added atmospheric nitrogen from car exhaust.
Heil agrees with Brand and Mitsch about the need to control nitrogen runoff in general, even if she does not anticipate much impact on red tide. The costly campaigns to do this are necessary, she said, because septic runoff is definitely a major cause of the other algae scourge of this summer, blue green algae. Also known as cyanobacteria, that freshwater organism has wreaked havoc on the center of the state around Lake Okeechobee. Releases from the giant lake then spoiled waterways on coastal communities both east and west, with the west getting the worst of it, according to research.
And other kinds of algae, caused by uncontrolled septic releases, have polluted harbors such as Charlotte Harbor, Heil said. The result is water that is no longer clear and no longer supports sea grass that wildlife need.
To tackle red tide, the new Red Tide Institute is looking at controlling its effects, called mitigation. Options to be studied include spreading clay particles on the surface of coastal waters anticipating that it would clump together with Karenia brevis and pull it to the bottom.
Another option to study, Heil said, is to try and capture the aerosol irritant before it floats inland.
Early attempts to control red tide, such as in the 1950s, were disasters, Heil said. They dropped copper sulfate in the Gulf to kill red tide, which it did. But red tide returned shortly with a vengeance.
“Nowadays, crop dusting the Gulf of Mexico is not a good idea,” she said at the summit.
Brand and Mitsch are not impressed by the idea of physically controlling an outbreak that spreads hundreds of miles along the costs of Florida.
“They spent millions of dollars trying to do that this summer,” Brand said of recent experiments in closed canal or aquarium systems. “That’s miniscule compared to the miles of Gulf Coast.”
“That’s a waste of time,” said Mitsch, adding sarcastically, “Good luck.”
“The only way we’re going to control this is to control the nitrogen coming out of our atmosphere and out of our landscapes,” Mitsch said.
Heil said the institute will be bringing together people from across the globe where similar saltwater red tide blooms flourish. From these people, Heil is hoping for groundbreaking new ideas.