More data needed to understand algal blooms

OKEECHOBEE — While it was widely assumed in media reports that the algal bloom on Lake Okeechobee in 2016 seeded the massive bloom on the Treasure Coast that summer, that theory needs more scientific investigation, according to H. Dail Laughinghouse IV, Ph.D. Assistant Professor-Applied Phycology Department of Agronomy Fort Lauderdale Research and Education Center University of Florida/IFAS.

Some data have indicated this, but scientists can use molecular markers to try and determine if they are the same algae, he said.”Though they can be the same species, determining if they are the same population or strain is a bit more complex.”

“I don’t know if anyone has done this,” he said.

“People tend to want to point fingers at others,” he said.

The assumption that “it must have come from the lake” because a bloom covered nearly a third of the Big Lake’s surface, and because water from the lake was flowing through the Port Mayaca Lock into the C-44 canal which connects the St. Lucie waterway, is just a theory.

Fishermen noted the feathery, translucent algae that appeared and disappeared on the lake surface looked nothing like the thick mats of goo – labeled “guacamole algae” by the press – seen on the Treasure Coast in 2016.

If the “guacamole” algae did come from the lake, it must have come in contact with “a nutrient soup” in the Treasure Coast that made the bloom grow the way it did, said Dr. Laughinghouse.

One reason the Treasure Coast bloom grew so rapidly could have to do with ammonia, a form of nitrogen that is easy for algae to metabolize. Some scientists suspect Treasure Coast septic tanks leaked enough ammonia into the waterways to cause the algae bloom to turn to the “guacamole” form.

“When water has fecal coliform bacteria, that indicates there is probably leaching,” said Dr. Laughinghouse.

The conditions may have been ripe for an algal bloom, and all that was needed was enough freshwater to lower salinity levels, and algae from the lake to seed it.

However, that it not the only possibility.

The water in the Treasure Coast waterways is not sterile, he said. The species of algae found along the Treasure Coast in 2016 are normal phytoplankton in waterways, he continued. “We just don’t know the quantities.”

While salinity levels are a factor, different species of algae are capable to tolerate and grow different salinity levels.

And because algae is highly adaptable and can quickly evolve to fill any available niche in an ecosystem, some species of algae can grow in salt water.

“Microcystis is considered a freshwater species, but data show that some strains have evolved to tolerate certain salinity levels,” he said.

“Blue-green algae are freshwater algae, but we know a brackish system has a species of algae that has evolved to tolerate that.” In 2016, he pointed out, “we saw these big blooms way out into the ocean.”

The highest level of toxins from an algae bloom in 2016 was from a bloom about five meters offshore at Bathtub Beach, according to Dee Ann Miller of the Florida Department of Environment Protection. The toxin levels for that bloom were 414.3 micrograms per liter. (The World Health Organization (WHO) advises limited contact to water with algal blooms where toxin levels are more than 10 micrograms per liter.)

At the same time the record level was set 5 meters offshore, there were no detectable toxins in the water closer to shore, said Ms. Miller.

It’s possible the algae came from the lake, said Dr. Laughinghouse. Without concrete data, there is no way to be certain.

The algae in the lake water that flowed into the system from Lake Okeechobee could have died when it hit the St. Lucie waterway due to the increased salinity, he explained. As the freshwater from the lake lowered the salinity levels in the coastal waterways, algae already in the St. Lucie system could have grown into the “guacamole.” Or the algae in the water from the lake could have grown into the “guacamole” due to the high level of ammonia due to the runoff in that watershed.

According to data from the South Florida Water Management District, on a 5-year average, lake releases make up about 20 percent of the freshwater entering the St. Lucie waterway and account for about 13 percent of the phosphorus. Runoff from the basin is higher in phosphorus than is the water from the lake. In the very wet 2016, when heavy rainfall in the upper Kissimmee River rapidly pushed the lake level over 16 feet, releases to the St. Lucie accounted for 40 percent of the freshwater entering that system and about 30 percent of the phosphorus. While that lake water was still comparatively cleaner than the basin runoff, the rapid flow of freshwater from the lake disrupted the salinity levels along the coast.

In 2017, no water from the lake has flowed through the Port Mayaca Lock.

Because the lake was left below 12 ft. by drought conditions early in the year, water from the C-44 canal backflowed into Lake Okeechobee. The water from the C-44, more than 24 billion gallons of untreated runoff from that basin, averaged around 300 ppb phosphorus, while the lake water averaged around 128 ppb phosphorus during that period, SFWMD records show. In a twist, it is likely the flow into the lake from the C-44 fed an algae bloom on the lake near Port Mayaca, according to SFWMD water quality specialists.

To better understand the water quality issues, and resolve the threat of toxins from algal blooms, more data are needed, said Dr. Laughinghouse.

“A lot of data are lacking,” he said.

Florida does not have constant, yearlong monitoring of the algae in many of these places, he said. To find the answers, year-round monitoring is needed.
“More should be done to give people concrete data,” he said.

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