March 13, 2017
Can we get rid of red tide? Not yet, according to Mote scientist
By Elizabeth Djinis
SARASOTA — As one of Mote Marine Laboratory's resident red tide researchers, Richard Pierce, lectured on the facts and future of red tide Monday evening, one question kept coming up from the audience: What can we do to stop red tide?
One man suggested changing the water density in red tide-affected parts of the Gulf of Mexico. A woman wondered whether alternate forms of energy could have an effect. But the consensus from the panel of Mote red tide scientists at the talk was clear: At this point, there is no sure way to eradicate red tide or even significantly lessen the concentration of the blooms of Karenia brevis, the red time organism.
"It's not currently possible to control red tides in the Gulf," Pierce, Mote's assistant vice president for research and the program manager of its Ecotoxicology team, said while concluding his lecture to a filled hall of about 150 people. "In many cases, we can reduce the risk, but we probably won't get rid of it."
In the meantime, Mote scientists have made some promising discoveries, such as an algae byproduct that could inhibit red tide growth and its toxins, according to Pierce. The Phytoplankton Ecology team, led by program manager Vincent Lovko, is working on that prospect, but both Lovko and Pierce said it was in the trial period.
"We're not going to go out there and start dumping things in the water," Pierce said. "But there could be ways we could knock it back or at least control it within specific areas."
Before Pierce delved into all of the possible ways to mitigate red tide's effects, he focused on its little-known origins. One of the widely held myths about red tide is that it is a direct effect of human impact on the environment, much like global warming. But Pierce said that is not so — in fact, one of the earliest cases of red tide occurred in the 1500's and was documented by Spanish explorers along the Florida Gulf Coast. The phenomenon occurred far before the Industrial Revolution, Pierce added, and emerged as a "periodic occurrence."
He displayed a chart to show the various nutrients the organism uses to survive, including mineral deposits from swamps and dust blown over from the Sahara Desert. But just how the organism is formed — and what its biological purpose is in the first place — is difficult for scientists to say.
"It's a very complicated mish-mash of sources and types of nutrients that are utilized by the Karenia brevis," Pierce said. "We often say, 'This isn't rocket science, it's far more complicated.'"
When fish consume the organism in the water, they are harmed by what are called neurotoxins, which affect their nervous systems and essentially make them "nervously excited to death," Pierce said. That accounts for the dead fish that line the shore during a particularly high concentration of a red tide bloom.
But what of the respiratory effects in humans? Those drift up from bubbles in the water, which turn into air bubbles and affect noses and eyes of people near the shore. While red tide symptoms are generally noticeable only when someone is near the water, there can be serious poisoning from consuming shellfish with these toxins. The immediate indications of that include slurred speech, partial limb paralysis, nausea, and a feeling like one's nerves are on fire.
What Mote scientists ultimately want to do is predict and understand red tide movements and growth. One of Mote's overall goals is to establish a total coastal observation system, which would span the Gulf Coast and give people interested in going to the beach on any part of the Gulf coast a better sense of what they might find there.
Since Florida red tide is found mainly in the Gulf of Mexico, one of the last questions of the night had a woman asking why the organism was not found elsewhere. Was there something other ecosystems had that we didn't?
"It exists here because this is where it grows well," Pierce said. "This is an area where this organism can thrive and overcompete."