By Suzanne Townsend
Date: 12/15/2022
TAMPA–Floridians are all too familiar with the regularly occurring red tide and its consequences. Beachgoers arrive hoping for a relaxing day of swimming and shelling only to be plagued with cough and the stench of decaying fish.
Red tide is a naturally occurring periodical bloom of the phytoplankton or single-celled algae called Karenia Brevis. The organism has been documented in the Gulf of Mexico since the 19th century but recently it’s been exacerbated by excess nutrients and increased water temperatures. The harmful algal blooms of Karenia Brevis suck the oxygen out of the water and release a toxin deadly to fish and other marine life, as well as having adverse effects on humans. This negatively impacts the tourism industry that Florida’s economy heavily relies on and in some cases has caused respiratory infections that land affected
people in the ER.
The impacts of red tide are felt first and foremost by businesses that rely on the ocean. Captain Dustin Quesenberry has been with Poseidon Fishing Charters of Tampa Bay since 2020. He recalls recent blooms and the effects it had on business. “We did have fewer bookings just because it’s all over the news. Bait was a big issue and catching fish was a big issue because most died. Then they go to different areas when the red tide affects the water, so that was our main struggle.”
David Karlen, an environmental scientist with the Environmental Protection Commission of Hillsborough County, says the fish kills can be costly in cleanup expenses and tourism. “The other issues are respiratory issues. People with asthma or other respiratory issues are susceptible to the toxins in the algae that get released into the atmosphere. Currently, there’s a bloom occurring south of us near Lee County that reaches up toward the mouth of Tampa Bay so we’re going to see more bloom impact in the coming weeks.”
What causes red tide?
Karenia blooms begin offshore in the Gulf, but the main problems arise once it makes its way to shore. Rhonda Watkins, a member of the Harmful Algae Bloom Task Force, wants people to remember that red tide is naturally occurring.
“It’s never going away,” she said in a phone call.
But it has gotten worse in southwest Florida. One cause of the increased algal blooms is temperature, according to a University of Florida study. Higher water temperatures due to climate change have been found to enable the proliferation of toxic phytoplankton, making red tide worse for Florida.
“It also has been documented that nutrients and temperature act synergistically in the ocean to stimulate the growth of harmful phytoplankton blooms,” Watkins said.
Nutrients are a big component in exacerbating existing red tide once it gets closer to the coast.
“Once red tide is near the coast it will consume any nutrients available to it. There are nutrients in any coastal runoff that can exacerbate an existing red tide, it can sustain it for longer than it typically would be here,” Watkins said.
Nutrients that Karenia feeds off of include nitrogen and phosphorus which can come from fertilizer and sewage and it’s only becoming worse due to land development.
When asked about the role of Florida’s sugar industries in excess nutrient runoff, Watkins says they’re not the main culprit. “The thing is that I know everybody wants to blame Big Sugar but Big Sugar has been here since the 60s, so nothing that they’re doing is changing. The thing that has changed is development and we know that the rules that we have for development for stormwater runoff are not addressing the nutrients in the water. Then you compound that with the number of people that are moving here and that’s more sewage, that’s more biosolids…” That’s more fuel for red tide.
One example of a bad red tide happened in July of 2021 after the Piney Point wastewater leak in Manatee County. In March 215 million gallons of wastewater was pumped into the Bay, and in July the Tampa Bay Times reported that almost 2,000 pounds of dead sea life was picked up in the Tampa Bay area alone. Red tide usually naturally affects Florida’s coast during the winter months, so this unusual summertime bloom can be linked to the wastewater leak.
There are clear connections between climate change and harmful algal blooms when we look at unusual storms, too. According to NOAA, hurricane season in Florida lasts from May to November. Still, Tropical Storm Alberto in May of 2018 was a somewhat unusual occurrence. This storm led to another bad red tide that lasted all summer, again, an unusual time for a bloom. Storms and hurricanes cause upwelling of nutrients from the bottom of the Gulf, as well as increased runoff from land, feeding outbreaks of Karenia.
What needs to be done?
Mote Marine Laboratory in Sarasota and the Florida Fish and Wildlife Research Institute are the main researchers investigating red tide. As for what everyday people can do, both Karlen and Watkins urge people to limit the use of fertilizer.
“Recommendations at the state level are either not passing legislation or the rules that they’re revamping are so watered down that it’s not gonna make a difference,” Watkins said.
“We should stop growing grass. That’s really one of the best things you can do, it’s such an artificial crop and it takes so much energy and nutrients to maintain. Grow food, grow anything else,” Watkins warns.
Florida has a long way to go with its research, but the more residents know, the more proactive they can be in taking care of their natural environment.
Student journalist Suzanne Townsend wrote this report for the Basic Reporting class of instructor Vidisha Priyanka for the Fall semester of 2022 at the University of South Florida.
