Southampton unleashes ultrasonic devices in battle against algal blooms on Lake Agawam

Scientists will study underwater ultrasonic waves in combating the blue-green algae that invades Southampton’s Lake Agawam every summer, covering it in a pea soup-like algal bloom.

The state Department of Environmental Conservation deployed three solar-powered ultrasonic devices Wednesday atop floating buoys in the lake that will also transmit real-time data. The DEC, working with Southampton Village, the nonprofit Lake Agawam Conservancy and the Gobler Laboratory at Stony Brook University, will study the effects of ultrasonic waves when combined with applications of hydrogen peroxide.

Jacqueline Lendrum, a DEC research scientist who is working with new technologies to combat harmful algal blooms, said the experiment is being deployed now to stay ahead of the blooms, which typically begin in late spring.

"This lake by July, August, the whole thing is green," Lendrum said. "Trying to tackle that is extremely hard. The thought is that this will prevent that sort of bloom from setting in."

Blue-green algae, also known as cyanobacteria, thrive in warm, nutrient-rich still water. The algae species in Lake Agawam emits a toxin known as microcystin that can cause breathing, digestive and liver problems, or even death.

Ultrasonic waves transmit a frequency that essentially pops air bubbles in the cyanobacteria, making it impossible for it to float to the top and get the sunlight needed for photosynthesis.

The devices are manufactured by LG Sonic, which is based in the Netherlands, and cost about $100,000 each, according to the state. The DEC has used smaller ultrasonic devices in some waterbodies upstate, but the Lake Agawam systems are the largest used to date and the first on Long Island. Officials said they feel confident the systems do not harm fish.

The second part of the experiment will add hydrogen peroxide-based product to the lake that breaks up cell walls and kills bacteria twice over the summer. The village and the Lake Agawam Conservancy will each pay $84,708 for an application, Warren said.

"We know in other situations that hydrogen peroxide will knock back the harmful algal bloom very quickly," Lendrum said. "But it doesn’t have any staying power to prevent the bloom from rebuilding or regrowing."

The hydrogen peroxide breaks down into water when it’s poured into the lake, so it doesn’t otherwise harm the ecosystem.

The Southampton lake was a prime candidate for the experiment because it has reliable annual blue-green algae blooms and because professor Christopher Gobler of the Stony Brook University School of Marine and Atmospheric Sciences has been monitoring it since 2003.

Officials stressed that the experiment is not a cure-all and that making the lake healthier will require addressing the nutrient sources, which according to the state’s harmful algal plan are sediments at the bottom of the lake, runoff and septic system wastewater

The hope is that the community will see a noticeable difference in the lake this season.

"We’re hoping that this summer instead of having one of the most dense and toxic algae blooms, we’ll actually severely mitigate them, if not completely eliminate the toxicity," said Southampton Village Mayor Jesse Warren.

By Vera Chinese

vera.chinese@newsday.com@VeraChinese

Vera Chinese joined Newsday in 2017 after working as an editor for the East End lifestyle publication northforker and a general assignment reporter for the New York Daily News.