University of Florida scientist: Blue-green algae blooms can be killed, but ...

Tyler Treadway | Treasure Coast Newspapers

Is there any way to get rid of the small algae blooms now in the St. Lucie River to keep them from becoming big ones like in 2016?

The answer is a qualified "yes," said a University of Florida algae expert, but the results might not last long, and they could come with some serious unintended consequences.

"The bottom line is that any quick fixes won't resolve the bigger issue, which is stopping the discharges that are the underlying cause of the blooms," said Ed Phlips, a UF fisheries and aquatics professor.

Since June 1, the Army Corps of Engineers has discharged about 10.5 billion gallons of Lake Okeechobee water into the St. Lucie River. Combined with billions more gallons from canals, creeks and ditches, the river's estuary at Stuart has turned from salty to fresh and is full of nutrients to feed blooms.

More: Algae pops up in St. Lucie River as discharges continue

Since June 6, patches of blue-green algae — most of them small, some ephemeral and a couple slightly toxic — have appeared.

Scientists and veterans of past blooms fear the small patches of algae now are a harbinger of bigger blooms to come, like those that blanketed the river with dense, toxic mats of putrid algae.

Video: 2016 Algae Bloom Timeline In the summer of 2016, discharges from Lake Okeechobee caused widespread toxic algae blooms in the St. Lucie River.

Early this year, the Florida Department of Environmental Protection solicited proposals for "the containment, removal, cleanup, elimination, transportation and disposal of harmful algal bloom and by-products."

"A total of four responses were received," said DEP spokeswoman Dee Ann Miller. "Two were incomplete; neither of the other two scored high enough to be considered for a contract."

The department is "revising the scope of work based on feedback from vendors and will be issuing another solicitation soon," Miller said.

Here are some proven methods for getting rid of small algae blooms, and Phlips' assessments of how they would work, or wouldn't work, in the St. Lucie River:

Kill it with algicides

A number of chemicals, most including some form of copper, commonly are used to control algae blooms, particularly in freshwater ponds.

The problem, Phlips said, is algicides don't work well in large bodies of water with tidal flows and massive influxes of fresh, fertilizer-laden water — the St. Lucie River estuary.

"You could try to use an algicide on a small patch of algae," Phlips said, "but the chemicals would get diluted pretty quickly and be ineffective."

And if the chemicals did kill the algae, he said, there could be more problems.

First, the dying algae cells, if they're toxic, would release their toxins into the water, causing a threat to people and small marine animals.

Second, the sudden death of so many algae cells would cause a feeding frenzy by bacteria in the water, removing oxygen from the water and possibly causing a fish kill.

Needs salt

Blue-green algae can't survive in salty water.

Even for a small patch of algae, Phlips said, an enormous amount of salt would be needed to raise the water's salinity enough to kill algae.

As with algicides, tides and influxes of fresh water would disperse the salt quickly; and more salt would be needed as more fresh lake water is discharged into the estuary.

Any small benefit, Phlips said, would be short-lived.

Skim the top

Much like oil spills are removed from water, the idea is to scoop up algae using specially designed skimmer boats.

"If the algae is thick enough to be picked up in the skimmer, it would work," "Phlips said.

But there are problems.

"You've got to do something with the algae you skim up," Phlips said. "If it's toxic, you don't want to put it on fields, and you might not want to put it in a landfill."

And again, the effect would be temporary.

"It might be aesthetically pleasing to have the bloom behind your house gone for a while," he said, "but as long as there are discharges, there'll be another bloom coming in behind the one you scooped up."