What is causing Florida’s algae crisis?
Two large-scale algae outbreaks in Florida are killing fish and threatening public health. Along the southwest coast, one of the longest-lasting red tide outbreaks in the state’s history is affecting more than 100 miles of beaches. Meanwhile, discharges of polluted fresh water from Lake Okeechobee and polluted local runoff water from the St. Lucie and Caloosahatchee watersheds have caused blooms of blue-green algae in downstream estuaries on both coasts. What has been the impact on Florida?
The outbreak, which began in October, has killed countless fish and marine mammals from Bradenton to Naples. More than 2,000 tons of dead marine animals have been removed from the coasts of the five hardest-hit counties, according to cleanup reports.
Business owners in the hardest-hit counties report they have lost nearly $90 million and have laid off about 300 workers because of the red tide and a separate freshwater algal bloom in the state’s largest lake. Together, the two blooms have caused a sharp drop in tourism.
Gov. Rick Scott has taken steps to address the outbreak, declaring a state of emergency, providing millions of dollars to help small businesses and directing his Department of Environmental Protection to partner with the Mote lab to track the algae bloom.
His detractors point out that after he was first elected, appointees Scott placed on boards that govern state water management districts cut $700 million from their budgets, including money for red-tide research.
What’s the difference between red tide and blue-green algae?
A pair of toxic algal blooms striking the state at the same time is rare and, in this case, especially lethal.
Both are photosynthetic microscopic organisms that live in water. Blue-green algae are properly called cyanobacteria. Some species of cyanobacteria occur in the ocean, but blooms — extremely high levels that create green surface scums of algae — happen mainly in lakes and rivers, where salinity is low.
The red tide’s poisonous algae is a variety of dinoflagellate called Karenia brevis that is native to the Gulf of Mexico. It produces a neurotoxin that disorients and paralyzes marine life.
What causes these blooms?
Blooms occur where lakes, rivers or near-shore waters have high concentrations of nutrients , such as nitrogen and phosphorus. In Lake Okeechobee and the St. Lucie and Caloosahatchee estuaries, man-made nutrient pollution from their watersheds is causing the blooms. Very high levels of nitrogen and phosphorus are washing into the water from agricultural lands, leaky septic systems and fertilizer runoff.
Red tides form offshore, and it is not clear whether or to what extent they have become more frequent. When ocean currents carry a red tide to the shore it can intensify, especially where there are abundant nutrients to fuel algae growth. This year, after heavy spring rains and because of discharges of water from Lake Okeechobee, river runoff in southwest Florida brought a large amount of nutrients into nearshore waters of the Gulf of Mexico, which fueled the large red tide.
How dangerous are they for humans?
The public health advisories about red tide are related to respiratory irritation, which is a particular concern for people with asthma or other respiratory issues. But almost anyone who has walked a beach where there is a red tide will quickly experience watering eyes, a runny nose and a scratchy throat. The algae that cause the red tide release a toxic chemical into the water that is easily transported into the air where waves break on the shore.
Some people are allergic to cyanobacteria blooms and can have contact dermatitis (skin rash) on exposure. It is not advisable to purposely contact water with a cyanobacteria bloom. And if farm animals or pets drink water with an intense bloom, they can become seriously ill or die.
Can the blooms be stopped?
Over the years, scientists who study the gulf have come a long way toward perfecting the way red tides are tracked. But they are not close to figuring out how to stop them, or redirect them from the shore, where they do the most harm. They have considered everything from dropping clay on the algae to infusing it with ozone or hydrated copper sulfate. But those treatments could be costly — and might not work.
“We don’t have an algae problem in Florida,” said Andy Mele of Suncoast Waterkeeper, a nonprofit watchdog. “We have a nutrient problem in the state.”
The only way to stop giant algal blooms, he said, is to stop nutrients from polluting the water.