Aside from some recent flare-ups — like the toxic algae found in the St. Lucie River this past spring and the near-constant algae in Lake Okeechobee — Florida waters have mostly been spared the massive, guacamole-like blue-green algae blooms that choked waterways in 2005, 2013, 2016 and 2018.

But research shows algal blooms around the world are getting bigger and more frequent.

For a microscopic organism, blue-green algae is incredibly complex. It can cause devastating damage to ecosystems, but it also is a fundamental building block of the environment. It can cause serious physical harm to people, but none of us would be alive without it.

So cue the Spaghetti Western music: It’s time for “The Good, the Bad and the Ugly” about blue-green algae.

The Good

Blue-green algae is actually cyanobacteria, a naturally occurring microscopic bacteria that, like plants, use photosynthesis to produce food from nutrients and sunlight.

The name “cyanobacteria” comes from the ancient Greek word for blue, “kúanos,” referring to the blooms’ bluish green color.

Cyanobacteria are some of the oldest organisms on Earth (with fossil records dating back at least 2.1 billion years) and the first organisms known to produce oxygen.

That’s why, without cyanobacteria, we wouldn’t be here. By continuously producing and releasing oxygen over billions of years, cyanobacteria are thought to have given the early Earth’s atmosphere enough oxygen for life as we know it. 

Cyanobacteria are probably the most numerous group of organisms to have ever existed. Types of cyanobacteria can be found in almost every land and aquatic habitat — salty water in oceans and estuaries, fresh water, damp soil and even temporarily moistened rocks in deserts and Antarctic rocks. 

Low amounts of blue-green algae in the water make for a healthy ecosystem, providing a valuable food source for critters at the bottom of the food chain and turning carbon dioxide into oxygen so all of us can breathe.

In fact, a type of cyanobacterium called Prochlorococcus is estimated to produce 20 percent of the oxygen in the atmosphere, according to an article in Smithsonian magazine: “One in every five breaths you take, you owe to Prochlorococcus.” 

But when blue-green algae blooms, ecosystems can go from good to bad in a hurry.

The Bad

Several conditions in a body of water — often in combination — can cause normal levels of blue-green algae to explode into ugly, stinky and often toxic blooms: high levels of nitrogen and phosphorus from fertilizer runoff and septic tank leakage; long, hot days; and low salinity. 

(It should be noted that the St. Lucie River and Indian River Lagoon — estuaries with naturally brackish, or  somewhat salty, water that repels algae growth — never get large algal blooms without massive releases of fresh water from Lake Okeechobee, water that often already contains an algal bloom or at least high levels of bloom-feeding nitrogen and phosphorus, from Lake Okeechobee.) 

Even blooms that aren’t toxic can harm a water body by blocking sunlight and killing sea grass, a vital part of the ecosystem that provides food and habitat for numerous species of fish and invertebrates.

To add insult to injury, a bloom can continue to wreak havoc on an ecosystem after it dies: Bacteria eating the dead cells suck all the oxygen out of the water, which can cause fish kills.

But things get really ugly when the cyanobacteria begin producing toxins.

The Ugly

A type of cyanobacteria called Microcystis aeruginosa has been the primary blue-green culprit in St. Lucie River blooms. It produces several toxins, including one called microcystin.

Short-term exposure to microcystin during recreational activities — touching infected water or breathing in tiny water droplets — can cause stomach pain, skin rash, headache, coughing, watery eyes, nose irritation and sore throat. 

In just two days during the massive blue-green algae bloom in the St. Lucie River during the summer of 2018, Martin Health System emergency rooms, clinics and primary care doctors treated 15 people for symptoms consistent with algae toxins. They all reported they had contact with the river water within the previous seven days. 

And those are just the short-term effects of exposure to microcystin. The long-term effects may be much worse.

“Vomiting, nausea, fever, myalgia, hallucination, liver and kidney diseases and cancers, neuromuscular problems and potentially even death are all symptoms of more severe CyanoHAB (harmful algal bloom) exposure,” according to the U.S. National Office for Harmful Algal Blooms. 

An Ohio State University study published in 2015 found people living in areas with significant blue-green algae blooms containing microcystin are more likely to die from nonalcoholic liver disease than those in areas without the blooms. 

To be clear: While the study found a suspicious link between microcystin, which is often found in blue-green algae, it did not go so far as to confirm that blooms cause liver disease, especially not in particular individuals.

Martin, St. Lucie, Indian River and Okeechobee counties make up a “cluster” with a high rate of both blooms and deaths, according to OSU researchers. It’s the only such cluster in Florida and one of 65 scientists found nationwide.

Researchers compared data on blooms and deaths at the county and national levels from 1999 to 2010, so it included blooms related to Lake Okeechobee discharges of 457.2 billion gallons of water over 21 months — September 2004 to April 2006 — when hurricanes Frances, Jeanne and Wilma hit the Treasure Coast.

The study also included discharges from April 2003 to April 2004 and a release in 2010. It did not include data on the massive discharge-caused algal blooms in the St. Lucie in 2013 and 2016.

A number of scientists think another toxin in blue-green algae known as BMAA can trigger diseases such as Alzheimer’s, Parkinson’s and amyotrophic lateral sclerosis, also known as ALS or Lou Gehrig’s disease.

Research at Arizona State University on the causes of ALS published in April 2022 in Science of the Total Environment strongly supports the hypothesis that the cyanobacterial toxin BMAA is the top environmental cause of ALS. 

We’re not alone

Florida isn’t alone in suffering from harmful algal blooms. According to the U.S. Centers for Disease Control and Prevention, HABS have been reported in all 50 states, Puerto Rico, the U.S. Virgin Islands and throughout the world. 

In 2014, cyanotoxin concentrations were so high in Lake Erie, the water source for Toledo, Ohio, that the water utility issued a ‘Do Not Drink/Do Not Boil’ warning that lasted three days.

The Minnesota Pollution Control Agency warns: “When temperatures climb and the summer sun beats down, conditions are ripe for Minnesota lakes to produce harmful algae blooms, some of which can be harmful to pets and humans. When in doubt, best keep out!” 

Health and environmental protection agencies in states throughout the country maintain blue-green algae bloom trackers. (The Florida Department of Environmental Protection has a Blue-Green Algal Bloom Dashboard to track blooms in the state. 

More ugly news: HABs are becoming more frequent, severe and widespread.

A study using satellite data to track algal blooms all over the globe between 2003 and 2020 found blooms increased in size by about 13 percent, or 1.5 million additional square miles, and increased in frequency by 59 percent. 

“Scientists continue to document many effects of climate change on freshwaters, estuaries and marine environments; and those effects are predicted to be exacerbated in the future,” the U.S. Environmental Protection Agency reported in March.

“These effects, along with nutrient pollution, might cause algal blooms to become more severe and to occur more often in more waterbodies.”

Climate change enhances harmful algal blooms throughout the world in several ways. The most obvious:  HABs thrive in warm waters, and greenhouse gas emissions increase temperatures, including water temperatures.

In Florida, the development of wetlands into farmland has also led to more and larger algal blooms, as noted in “Florida’s Toxic Algae Crisis” by the Florida Bar Animal Law Section.
Wetlands naturally filter rainwater as it flows slowly into aquifers and estuaries; but draining wetlands for farmland causes the water to flow quickly through canals, removing the natural filtration.

The situation only becomes worse when the farmland — citrus groves, sugarcane fields and grazing land — is fertilized with nitrogen and phosphorus.

“When Florida waters are polluted by excessive amounts of these nutrients, the nutrients feed the algae and cause excessive — and harmful — algae blooms,” the Florida Bar report states. “Sewage sludge dumped on farms as well as leaky septic tanks throughout the state also contribute to the pollution that fuels the algae blooms.”

To offset the increased threat of harmful algal blooms caused by climate change, improved water management practices — such as the Lake Okeechobee System Operating Manual, or LOSOM — are needed.

LOSOM, which went into effect this summer, is expected to reduce total Lake O discharges east to the St. Lucie River by 37%. It also is designed to improve beneficial flows west to the Caloosahatchee River while also reducing harmful discharges there by 37%.

“LOSOM isn’t a cure-all,” said VoteWater Executive Director Gil Smart. “When the lake gets really high, discharges will still blast the ‘northern estuaries’ in high volumes. But LOSOM provides the Corps with more flexibility and it’s the first plan that acknowledges the need to send more clean water south to the Everglades.”

Besides controlling water flow, more needs to be done to control water quality. Florida’s primary means of improving water quality, Basin Management Action Plans (aka BMAPs), aren’t working to control the flow of nutrients into waterways around the state via programs and strategies such as permit limits on wastewater facilities, urban and agricultural “best management practices”. 

That’s already obvious from looking at the data. It will become terrifyingly more obvious when the next massive blue-green algae bloom comes pouring out of Lake Okeechobee.