Red tide FAQ: What is it, and where does it come from?

- Red tide is nothing new to Florida, but the bloom that we’re seeing in 2018 is considered one of the worst in recent memory, according to many experts.  

Photos of dead marine life and sludgy canals are flooding many social media users’ feeds.  But so is a lot of misinformation.  Here are the basics about red tide and green algae, based on what experts at Mote Marine Lab and the Florida Fish & Wildlife Conservation Commission have said.

Q: What is red tide?  

A: It is a higher than normal concentration of microscopic algae. When it forms off the Gulf Coast of Florida, the specific culprit is a microorganism called Karenia brevis. 

Q: Why is it called ‘red’?

A: It can discolor affected water, sometimes (but not always) making it look brownish-red. 

Q: How does it kill marine life and make people sick? 

Karenia brevis produces brevetoxins. It can kill marine life at the lower end of the food chain, and poison shellfish and seagrass, which in turn sickens those who consume it). Brevetoxins can also seep into the air, sickening wildlife and people who breathe it. People with pre-existing breathing conditions are at the highest risk of having adverse reactions to exposure.

Q: Is red tide fairly new to Florida? 

A: No. There are accounts of red tide off the Florida coast for hundreds of years, long before Florida became commercially developed. 

Q: How long can it last? 

A: Weeks, months, and sometimes more than a year. Florida suffered through nearly a year and a half of red tide outbreaks from 2004 to 2006. 

Q: What causes the blooms to grow and spread?

A: Naturally existing Karenia brevis feed off a variety of nutrients. When there are higher levels of nutrients, they can explode into a bloom that can be spread by currents and wind patterns. These nutrients can include fertilizer runoff pollution. While environmentalists note the correlation between the flow of fertilizer-polluted water from Lake Okeechobee into the Gulf of Mexico, scientists have not drawn a direct link between lake runoff and the outbreak of red tide off Sarasota and Manatee counties.

Q: Is this the same organism that’s causing green slime in South Florida’s Lake Okeechobee? 

A: No. The blue-green algae bloom in Lake Okeechobee is caused by cyanobacteria, not Karenia brevis. Cyanobacteria expands in heat and also feeds off of pollution from nitrogen and phosphorous-based fertilizer. It can also cause health problems and researchers believe long-term exposure may be linked to serious conditions, including Alzheimer’s and ALS.  

Q: How did these pollutants seep into Lake Okeechobee and why is this polluted water flowing west into the Gulf? 

A: Environmentalists cite a variety of contributors, including septic tank leakage and dairy farm runoff to the north of the lake. However, fertilizer runoff from sugar farms near Lake Okeechobee have drawn much of their focus. The runoff seeps into the lake, feeding cyanobacteria, and a dike directs the flow of Lake Okeechobee east and west, driving water laced with fertilizer-based nutrients into the Gulf. 

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