News Press

October 22, 2016


Tiny organisms; big problems: too much algae fouls our water

Amy Bennett Williams


For now, Mary Ann Parson’s canal isn’t the color of peas, guacamole or Oscar the Grouch — all shades it’s turned during past algae blooms.

“It was bright green this summer,” Parsons says, and she knows it will be again.

Noxious algae overgrowth is one of Southwest Florida’s chronic water woes.

But just because the Cape Coral retiree expects the cyclical return of algae doesn’t mean she’s resigned to it. As a volunteer Lee County Master Gardener who teaches Florida Yards & Neighborhoods classes, Parsons uses her bully pulpit to both educate her students (many of them newcomers) about Southwest Florida’s chronic water challenges, and to exhort them to help turn the  tide.

Red tide, toxic microcystin blooms and poop-colored drift algae are all caused by different life forms, but what they have in common is the potential to make residents and visitors sick — figuratively as well as literally.

Some, like blue-green algae, are photosynthesizing microorganisms with no cell nuclei. Others, like red drift algae form large tangled plumes that wash up on beaches.


Though these algae-like organisms occur naturally in the environment, when they proliferate, or “bloom,” the public health consequences can range from irksome to dangerous, says epidemiologist Jennifer Roth.

"Red tide algae, for example, can cause respiratory effects (and) people with asthma and other respiratory conditions can be affected and they could have trouble breathing," Roth says. "Other people can feel a stinging or burning sensation, and usually the effects are correlated with how much red algae there is and how close it is to the shore."

Cyanobacteria, a huge group of organisms commonly called blue-green algae, can be dangerous as well. "Limit your contact with water if you see it," Roth says. Cyanobacteria toxins can cause symptoms ranging from sniffles to liver failure — even death, if ingested in large amounts.

And it’s not just human health that can suffer; the animals that live in and near water are affected as well.

The state’s manatees are undergoing what scientists call an “unusual mortality event” that’s already killed more than 150 manatees, according to the nonprofit Save the Manatee’s Club’s Director of Science, Katie Tripp. Partly to blame is a die-off of algae-shaded seagrass linked to algal blooms. “There are concerns that these prolonged blooms will shade and kill seagrass, eliminating the manatees' primary food source, and an important habitat for other marine species.”

Too much algae can make the economy queasy too. Earlier this year, as algae blanketed Florida’s east coast and slimed the Caloosahatchee, Gov. Rick Scottdeclared a state of emergency. Charter captains and hoteliers reported lowered bookings as some real estate professionals lost sales, blaming the fouled water.


Algae blooms are nothing new. Centuries-old historical reports refer to red tide, for example, and research scientist Rick Bartleson of the Sanibel-Captiva Conservation Foundation says cyanobacteria blooms almost every year in the Caloosahatchee, but their increasing frequency and severity point to human interference with natural systems.

Parsons says many of her students are "amazed to learn that our storm water is not treated first before it goes into our canals and the Gulf."

They also learn proper use of fertilizers and pesticides as well as effective natural treatments. "This program was developed by the University of Florida to combat water pollution and algae growth, Parsons says, though she's worried because Lee County laid off the Florida Yards and Neighborhoods agent in 2013.

"If the Lee County Master Gardener volunteers ... do not teach the proper use of fertilizers and pesticides, who will?" she asks. "If this program dies, then expect the algae problem and water pollution to get worse."

About algae

Algae is a blanket term for a number of organisms that naturally live in Southwest Florida. Here are a few that often make news:

Red tide is caused by an organism called Karenia brevis, which is visible only through a microscope and produces a powerful toxin which can kill fish and other aquatic creatures. It also can be harmful to people with respiratory issues.

Cyanobacteria, or blue-green algae, is a large group of organisms that photosynthesize but have no nuclei. High temperatures and water polluted with excessive nitrogen and phosphorus can feed their blooms, according to the federal Environmental Protection Agency’s website. Some produce toxins that can cause health problems ranging from hay fever-like symptoms to death.

Red drift algae, also called macroalgae, forms large feathery mats. These nontoxic organisms can be seen (and tripped over) when they wash up on the beaches. Their challenges are mostly aesthetic, since some consider them unsightly and they do become pungent with age.