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Red flags raised over toxic bacteria blooms

New Hampshire Union Leader

June 21. 2017 8:28PM
Cottages on the shore of Silver Lake in Hollis, where the state lifted a warning for high levels of cyanobacteria on Wednesday. (DAVID LANE/UNION LEADER)

Three cyanobacteria warnings for New Hampshire lakes so far this year suggest more frequent occurrences, but also that more people “understand intuitively that when you see scum on a lake, it is not a good thing,” says a leading researcher.

“We are certainly looking more for it than we used to be,” said James Haney, a researcher with the New Hampshire Agricultural Experiment Station at the University of New Hampshire and a professor of biological sciences.

“My guess is it is a combination of increased incidence and increased reporting.”

Cyanobacteria grow in colonies to form surface water “blooms,” usually blue-green in color and consisting of thousands of individual cells, according to the Department of Environmental Services.

The bacteria occur naturally in most New Hampshire lakes, usually in relatively low numbers.

But cyanobacteria can increase as nutrients in the water increase. They are also more commonly found in shallow lakes, where the bacteria is less likely to be diluted. And some cyanobacteria produce toxins can adversely affect humans, domestic animals and livestock.

Toxins can cause both acute and chronic health effects that range in severity. Acute health effects include irritation of skin and mucous membranes, nausea, vomiting, and diarrhea. Chronic effects include liver and central nervous system damage, according to DES.

The UNH researchers are reviewing data to see if they can form a hypothesis about what could be a link between cyanobacteria and severe neurological disorders such as amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease).

“We don’t know if it is cause or effect. It could be due to other factors, we are examining them in the lab,” Haney said. “Most who get sick are not eating the fish out of the lakes, maybe the toxins are being released into the air and being breathed as aerosols, that is the current hypothesis.”

They are also studying whether cyanobacteria is a factor in loon mortality rates on lakes that don’t have high lead content.

“We are finding surprisingly high quality of both liver and nerve toxins in the feather and blood of the loons,” Haney said. “It is detectable and at quite a high quantity.”

Three warnings

DES has issued a cyanobacteria advisory for Elm Brook Park beach in Hopkinton, the third such warning for a New Hampshire water body this season.

The warning went into effect on Monday and will remain until additional samples reveal cyanobacteria levels have diminished, according to DES.

On Wednesday, DES lifted a cyanobacteria advisory for Silver Lake in Hollis.

The agency had earlier lifted an advisory for Goose Pond in Canaan.

Amanda McQuaid is the beach program coordinator for DES, which monitors water quality at the state’s freshwater and coastal beaches.

She wasn’t surprised to see another lake added to the list this week. “We’ve had a lot of rain, and it can bring in a lot of nutrients,” she said.

“When you fertilize your lawn, you’re getting a green lawn, but that also can run off your lawn into the lake, and it gives you a green lake,” McQuaid said.

DES typically issues an advisory when a cyanobacteria bloom over a certain threshold is seen; the agency uses a threshold of 70,000 cells per milliliter to issue such advisories. It doesn’t necessarily mean that dangerous toxins are present, but that the potential is there.

Haney said the toxins can multiply in other waterborne organisms.

“It is very much like DDT and mercury in that respect. These toxins can be moved up the food chain and be bio-magnified, starting at a level of 1 and then getting up to a level of 1,000 in a large fish or a loon,” Haney said.

After exposure

DES does not close a beach if cyanobacteria is found, McQuaid said. “But we want people to know when they’re at high levels,” she said.

DES advises anyone who comes into contact with a cyanobacteria bloom or scum to rinse off with fresh water as soon as possible.

McQuaid advised people to avoid swimming and to keep children, pets and livestock out of the water if a bloom is visible. “If you can see it, it’s likely in concentrations that are high enough that there could be a contact issue,” she said.

Dogs are especially susceptible because they’re likely to drink the water and groom themselves after swimming, she said.

“Dogs are the mine canaries of the lake,” Haney said. “They will drink the water no mater how distasteful it is. They are sampling it for us.”

In addition to regular monitoring, McQuaid said, her agency relies on the public to report potential cyanobacteria blooms, which can appear as blue-green “globs” near the water surface. She said EPA scientists have developed a “bloomWatch” app that lets the public help track cyanobacteria blooms with their smart phones (for information, visit

But McQuaid warned that people shouldn’t collect water samples themselves “just because of how dangerous we think it could be.” Leave that to the experts, she said.;

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