DeSantis signed legislation establishing the red tide mitigation initiative.
In 1844 the fi rst documented red tide episode
in the United States waters occurred in the
Gulf of Mexico along the West Florida Shelf,
off the Panhandle near Panama City. In 1878
Florida experienced its fi rst long-term period
of red tide, which continued for ten years. A
widespread episode of bird deaths affected the
Florida Gulf of Mexico in 1880. It was believed
to have been the result of the red tide. In 1884,
the fi rst documented human illness from red
tide infected shellfi sh was recorded in Florida.
Florida’s red tides occur naturally in the
waters and are caused by a native species of
algae, Karenia brevis. Karenia brevis produces
brevetoxins that affect the central nervous
system of fi sh and other vertebrates and can
kill them, according to the FWC. When waves
break open the red tide organism’s cells it
releases the toxins into the air, which can cause
respiratory irritation, especially in those with
chronic respiratory conditions, like emphysema
or asthma.
The Florida Red Tide Mitigation &
Technology Development Initiative
Researchers at the Red Tide Institute
have been working to battle the red tide by
developing new tools and technologies. More
than 25 projects are already underway.
In one of the more promising projects, Mote
scientists are working with the Woods Hole
Oceanographic Institute and the University of
Central Florida to explore the use of clay to kill
red tide.
While there is no verifi ed method to eliminate
and prevent the red tide algae blooms,
spraying a clay mixture on top of the water has
been shown to weigh down the algae and drag
it to the ocean fl oor. Dry clay material was mixed
with seawater to create a slurry, which was then
dispersed over the water in the study area with
hoses. A screen was placed into the water on
one end of the canal, and water samples were
taken on both sides to compare the treatment
area with non-treated areas. What happens
next to the algae and the clay is also part of the
study.
It’s a routine algal bloom solution in parts
of Asia, but uncertainty about its long-term
environmental impacts has kept it from
widespread use in the United States.
Mote scientists are testing a clay method
by spraying small amounts of modifi ed clay
particles mixed with seawater on top of a red
tide bloom in a Sarasota canal. This method
is called clay fl occulation. As the dense clay
particles sink, they combine with red tide cells
and bury them in the sediment on the sea fl oor.
“What we’re seeing is that they die, and
they’re captured on the bottom,” said WHOI
Senior Scientist Don Anderson, who leads the
project.
Anderson says the amount of clay used is
so small that it would hardly leave a dusting
on the seafl oor. “It’s minuscule, like one onethousandth
of an inch,” said Anderson.