Hurricane Michael Could Worsen—or Alleviate—Florida’s Toxic Red Tide Outbreak

Hurricane Michael touched down Wednesday as an unprecedented Category 4 storm that pummeled the Florida Panhandle with winds of up to 155 miles per hour and storm surges of up to 14 feet. The storm could also trigger a welcome dissipation of the region’s red tide, a 145-mile stretch of toxic algal bloom that has plagued the coastal state’s marine wildlife and beaches since last November. Or, as Ephrat Livni notes for Quartz, Michael could do the complete opposite, generating excessive flooding that exacerbates the algae's harmful effects.

“In the past, it’s gone either way,” Tracy Fanara, an environmental engineer at Sarasota’s Mote Marine Laboratory, tells Craig Pitman of the Tampa Bay Times.

In one scenario, choppy waters brought on by the hurricane break up and disperse the red tide bloom, moving it offshore and leaving it to weaken as temperatures decrease. Bloomberg’s Christopher Flavelle further reports that Frank Muller-Karger, a biological oceanographer at the University of Maryland, predicts the algae couldn’t survive onshore for an extended period of time, as it would be unable to find sufficient nutrients.

On the other hand, the storm could push the red bloom inland, sending toxins into the air and sparking human respiratory issues similar to those caused by tear gas, reports Bloomberg’s Flavelle. It’s also possible that heavy rains brought on by the hurricane could make septic tanks, sewage systems and ponds overflow and release nutrients that actually fertilize the red tide, making it worse.

A similar situation may have played out in 2004, when four hurricanes hit Florida in quick succession, Fanara tells Pitman. That year, the state experienced one of the worst red tide outbreaks in its history; a so-called “dead zone” that stretched from New Port Richey to Sarasota was declared completely devoid of oxygen and marine life.

Then again, Hurricane Katrina, a 2005 storm that devastated the Florida peninsula and Louisiana, broke up the dead zone by pushing the red tide north.

Ultimately, hurricanes’ impact on red tide, and more specifically, Hurricane Michael’s effect on Florida’s current algal crisis, remains difficult to predict. As Richard Pierce, an ecotoxicologist at the Mote Marine Laboratory, explains to Bloomberg’s Flavelle, this is the first time the state has had to tackle severe red tide and a severe hurricane concurrently.

According to Vox’s Brain Resnick, red tide is an annual occurrence along the southwest Florida coast. A type of algae known as Karenia brevis is responsible for the toxic bloom, which can leave waters colored with a muddy brown or red hue. In small quantities, K. brevis is relatively harmless, but under certain conditions, it rapidly reproduces and releases toxins into both the water and the air.

Fish, birds, manatees, sea turtles and pygmy whales are amongst the creatures that have fallen victims to this latest bout of red tide, Glenn Fleishman writes for Fortune. Humans with existing respiratory conditions, as well as those who unwittingly consume contaminated seafood, have also been affected.

Florida’s current red tide outbreak has troubled the area for nearly a year, making it the longest one in more than a decade. Toward the middle of August, Florida Governor Rick Scott declared a state of emergency in the communities most devastated by the algal bloom, which poses a risk to not only the region’s wildlife and human communities, but the tourism industry residents rely on for their livelihood.

Ironically, Pierce tells The Verge’s Rachel Becker that the red tide had recently showed signs of abandoning the Florida coast.

“Based on what we’ve seen in Sarasota County this week, the red tide is pretty well gone,” he concludes.

Still, it’s possible that Michael will bring the algae back in full force or continue the dissipation process that Pierce says has already begun. Only time—and the conclusion of Hurricane Michael, which The New York Times reports is the strongest hurricane to ever come ashore along the Florida Panhandle—will tell.

Meilan Solly | | READ MORE

Meilan Solly is Smithsonian magazine's senior associate digital editor, history.