Robert Miller: The science behind annoying lake scum

[USA] Blue-green algae — creator of shoreline scum and pea soup-green water — is having a new burst of notoriety.

In the past few years, lakes throughout the state have had to close their beaches, rather than let people swim in a bacteria-laden, possibly toxic soup. In 2015, three town beaches on Candlewood Lake suffered this plight — Sherman, New Fairfield and Brookfield.

But none of this is exactly new. Cyanobacteria — the official name for blue-green algae — has been around for a very long time.

But maybe, because of climate change, we’re just going to have to get used to seeing it bloom on a more regular basis.

“This is not a Candlewood Lake problem,” Larry Marsicano, executive director of the Candlewood Lake Authority, said this month at the authority’s annual State of the Lake conference, held at the Sail Harbor lake community clubhouse in New Fairfield. “It’s not a Lake Lillinonah problem. It’s going to be a worldwide problem.”

Dealing with it will be complicated, only because cyanobacteria is complicated, adaptable and omnipresent.

“It’s always been in the lake, and it’s always been the predominant life form out there,” Marsicano said in an interview after the meeting.

Cyanobacteria are bacteria-like organisms containing chlorophyll in its cells. Like plants, they can photosynthesize sunlight and produce oxygen.

They are one of the oldest living things on the planet. Archaeologists in Australia have found 3.5 billion-year-old fossils with cyanobacteria.

About 2.3 billion years ago, blue-green algae suddenly bloomed worldwide with such vigor, they released a huge amount of oxygen into the earth’s atmosphere, in what’s called The Great Oxygenation Catastrophe. Because oxygen was toxic to many of the primitive bacteria on earth, the release of the gas caused a mass extinction of most living things.

The oxygen levels became so high they reduced the amount of greenhouse gases in the atmosphere. What followed was the Huronian glaciation — Snowball Earth — which occurred about 2 billion years ago and covered the earth’s surface with ice.

It may therefore be wise to remember when complaining about temporary beach closings blue-green algae has done far worse things. Granted, the water looks scummy. But at least, there’s no mass extinction or glaciers pushing the landscape around.

The cyanobacteria in lakes lives below the surface, feeding on the nutrient in those lakes’ lower levels. Humans now provide a lot of those nutrients. Stormwater runoff carries excess fertilizer as it flows downhill. Sewage treatment plants release nitrogen and phosphorus in their effluent that provides a banquet for cyanobacteria. So do faulty septic systems.

Cyanobacteria can position itself in the water at the perfect level to get nutrients from below and sunlight from above, Marsicano said.

“The little buggers can act like submarines,” he said.

If the water is calm and warm, with lots of nutrients to feed the algae, they multiple rapidly, and algae blooms. Sometimes, these blooms come with a release of toxins that can cause skin rashes and stomach illness in humans, and more serious problems to pets who swim in the water, then lick themselves clean.

At the State of the Lake conference, Marsicano and Edwin Wong, associate professor of biology and environmental science at Western Connecticut State University in Danbury, talked about the complexity of these ancient life forms.

For one thing, they bloom in deeper water. Winds then blow them into coves and beach areas, where people can see them more readily.

Marsicano said public health officials close beaches based on visual cues — how bad things look.

This can be misleading.

Wong said after the conference not all cyanobacteria produce toxins. So water that looks swampy may not be dangerous.

But, Wong said, bacteria is very good at passing its DNA around.

“That’s why bacteria can become resistant to antibiotics,” he said.

Therefore, it’s possible for toxin-producing cyanobacteria to pass that toxin-producing gene on. It can change.

Marsicano said evidence exists climate change is increasing the stratification of lake waters in the summer, with warmer, oxygen-rich water on top, cooler, oxygen-poor water below.

That in turn, may be leading to more frequent, and more severe algae blooms, he said. That has been the case at Candlewood Lake since 2012.

The lake authority hopes to get funding to work with Wong and his Western Connecticut State University laboratory, which can quickly provide area health officials with accurate data on algae levels, including information on whether the cyanobacteria can produce toxins.

Marsicano said — as he and others have said many times before — reducing the amount of nitrogen and phosphorus going into Candlewood Lake is the easiest, least complicated way of slowing cyanobacteria blooms.

People should limit the amount of fertilizer they use on their lawns, he said. They should check their septic systems, to make sure nothing is leaching into the lake. They should build buffer gardens to absorb runoff.

“It’s the low-hanging fruit,” Marsicano said. “If you can eliminate the easy things, it helps us with the big ones.”

Other solutions — using ultrasound pulses to kill the cyanobacteria, or adding chemicals to the water to reduce phosphorus levels, and deprive the cyanobacteria of a food source — are available. But they are expensive.

Given all these factors, people should not be surprised if blue-green algae blooms become more common on the lake, Marsicano said. Times and climates change. Cyanobacteria, as it always has, will adapt and thrive.

“They’re major producers of change in the atmosphere,” Wong said. “They’re everywhere.”


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