Mote Marine searches high and low for red tide instigator
The red tide organism requires nutrients, this we know. But desert sand from another continent could be a contributing factor to fueling the algae that plagued Florida’s Gulf coast last year.
“Saharan dust is an important factor in the initiation of (red tide) blooms,” said Cynthia Heil, director of Mote Marine’s Red Tide Research Institute, who cited other contributors such as the geochemistry of the ocean/
In June, tiny particles of dust from the Sahara Desert were picked up by winds, and carried across the Atlantic Ocean and over Florida and the Gulf of Mexico.
Eric Bunker, a meteorologist at the National Weather Service office in Tallahassee, told the Wall Street Journal in June, typically most summers see the dust carried, but it only reaches the U.S. a couple of times.
The dust particles refracted the light and created a dazzling display for sunsets, Bunker said.
The cloud to that silver lining is that the dust could help set the conditions for the next red tide bloom, the Naples Daily News reported Friday.
Dust events like the one in June, said NOAA oceanographer Rick Stumpf, come in pulses depending on wind patterns. They’ve been less frequent in the last 20 years but this was considered a bigger plume, attracting attention.
So how does red tide possibly benefit from the dust?
First it needs a little help from another organism, a filamentous cyanobacteria called Trichodesmium.
The dust contains iron needed by the Trichodesmium to thrive. In turn, Trichodesmium turns atmospheric nitrogen into ammonium, which feeds other organisms -- including Karenia brevis, which is responsible for red tide.
Scientists made the connection between trichodesmium and the red tide organism Karenia brevis and nitrogen years ago, according to Heil.
But Steven Leatherman, a professor in the Department of Earth and Environment at Florida International University and known as “Dr. Beach,” said there is still plenty of research to do.
“I think we should get some in the marine lab and test it,” Leatherman said.
“We’re not sure, there’s speculation but we need real science behind it.”
If there’s a lot of dust in a year, does that mean there’s a big red tide bloom coming? Not necessarily, Stumpf said, pointing out there was very little Saharan dust last year before a devastating red tide slammed into Anna Maria Island and elsewhere along the Gulf coast.
It’s not the main driver, but scientists can’t rule it out as a contributing factor.
“You can come up with a lot of answers but the short is the Karenia brevis is so good at finding nutrients wherever they are,” Stumpf said. “If it was the same thing ever year, we would know by now.”
Red tide usually comes around in September, Heil said, and she’s hoping this year’s is a mild round.
In the meantime, Leatherman wants people to stop fertilizing their lawns, as it runs off into the water and feeds red tide.
Several things feed the bloom but they’re not ready to point the finger at just one cause yet, Heil said.
With or without the Sahara dust, it’s still unclear how intense red tide will be this year. The end of August, Heil said, is when they’ll start looking for blooms to occur.
As of Friday, Karenia brevis was observed in background concentrations in one sample each from Pinellas County and Gulf County, according to the Florida Fish and Wildlife Conservation Commission.
“There is no active red tide that we know of right now, but it’s always around in background levels,” Michael Parsons, professor of marine science and director of the Vester Field Station at Florida Gulf Coast University told the Naples Daily News. “People need to just keep in mind that it’s always around a little bit, and it will be back, unfortunately.”