BONITA SPRINGS, Fla. — You might remember the headlines last fall, spinning fish from Florida Keys to Southwest Florida. But the big question was, what was causing that? The answer might surprise you.
“So many fish for effected,” said Dr. Mike Parsons, with Florida Gulf Coast University’s Water School. “We had the sawfish, unfortunately, and the sawfish were dying. But there were over 50 species of fish that were affected by this.”
In fall of 2023, reports of spinning fish were coming in from all angles in the Florida Keys. There were even a few reports here in Southwest Florida. At the time it was a big mystery as to the cause, but Dr. Parsons says his team might have solved the mystery.
“It’s called Gambierdiscus,” said Dr. Parsons.
Gambierdiscus is a type of microscopic Dinoflagellate algae that produces a neurotoxin 100 times more potent than Red Tide’s brevotoxin.
“We know that there are elevated levels of algae, or there were elevated levels of algae last spring,” said Dr. Parsons. “We know that they are producing these neurotoxins. We have measured all this. And nothing else has panned out.”
Dr. Parsons believes the fish were then exposed to these neurotoxins through their gills that they use to breathe.
“So, water is exposed right to capillaries, with their circulation system, it was going right into their blood stream,” said Dr. Parsons.
Dr. Parsons also suggests that species like the sawfish could also been ingesting the toxins by eating exposed fish.
Unfortunately, this neurotoxin likely led to the death of about 10% of the remaining sawfish population; a population already on the verge of extinction, with about 500 left in the wild.
“Other interesting part of this, is that it is not related to nutrients,” said Dr. Parsons.
That is unique because most of the recent harmful algal blooms are directly related to nutrient pollution.
“They are slow growing algae. They are more like the turtle in the turtle versus hare race,” said Dr. Parsons.
So, what caused the elevated levels of the Gambierdiscus? That is a question Dr. Parsons and his team are still trying to answer.
“Did it have something to do with last summer’s heat? Because it was really hot for a really long time,” said Dr. Parsons. “It was hot this summer as well, but we had breaks, some tropical events, other rain events, to help cool things down. So, we are gearing up, it started in October, we are getting ready to see if it fares up again.”
If it does flare up again, Dr. Parsons believes we are better prepared to respond and potentially save species like sawfish from exposure. But that still could be quite an undertaking.
