Vineyard group monitoring cyanobacteria blooms

Cyanobacteria, a potentially toxic blue-green algae, is no new sight to Islanders, but MV Cyano is now bringing regular, up-to-date monitoring of some of the Island’s freshwater and brackish ponds to the public for two reasons: the first, to monitor the safety of the water for people and animals, and the second, to study and protect the Vineyard’s ponds and ecosystems. 

Founded only three years ago, MV Cyano monitors cyanobacteria that exist in mixed fresh and salt waters, an area of science that Great Pond Foundation Executive Director Emily Reddington says has little been studied. MV Cyano hopes to keep the public aware of cyanobacteria levels in Island ponds in collaboration with the Great Pond Foundation and the Island boards of health, to promote safety for recreational users.

Warming water temperatures and nutrient-rich waters, made richer by nitrogen pollution from septic and agricultural runoff, are the primary contributing factors to these harmful algal blooms, according to Reddington and the foundation’s director of science and collaboration, David Bouck. 

Cyanobacteria creates a filmy layer or thick mat of algae on the edges and on the surface of freshwater and brackish ponds. Occasionally ponds, like Seth’s Pond, have been closed to the public due to hazardous levels of cyanobacteria. 

Cyanobacteria, when it blooms, may produce cyanotoxins, which can create potentially unsafe conditions for humans, pets, and livestock. While there is some risk to swimming and wading, the highest risk comes from ingesting cyanotoxins, for both people and pets. 

Not all cyanobacteria blooms produce cyanotoxins, and not all green algae lead to the toxic blooms. Not every pond that has a film of green algae is toxic. Knowing the difference is part of the work being done at MV Cyano, Reddington says. 

“We help the public to differentiate between nontoxic regular things you’d see in the water, and something potentially toxic, like cyanobacteria,” Reddington said. “Not all types of cyanobacteria are toxic, but what MV Cyano does is say, ‘When is there a risk, and what is it?’ so that people can still use the water.” 

Cyanobacteria can appear in many ways, and can be tricky to diagnose with the eye. “Blooms can look like a blue-green scum, can look filamentous like globby algae, or it can be toxic and the water looks clear,” Reddington said. “That’s why regular monitoring is really important.” 

Some ponds are monitored on a weekly basis, like Chilmark Pond and Edgartown Great Pond.

“It’s serious when you talk about cyanotoxins, and it shouldn’t be taken lightly, but it really depends on the type of toxin present and the concentration. The goal with MV Cyano is to try to get out public information quickly and effectively,” says Reddington.

MV Cyano and the Island’s boards of health work in collaboration to put up fliers to advise on the quality of the water and which activities are safe, have some risk, or are not advised. These notices are color-coded in conjunction with the maps uploaded on the website. On both website and flier, green indicates no cyanobacteria detected. The maps and more information on MV Cyano are available at greatpondfoundation.org/mvcyano. 

James Pond, Mink Meadows, and areas of Tisbury Great Pond and Chilmark Pond are currently displaying advisory levels for cyanobacteria. 

Reddington also encouraged anyone who suspects a pond not monitored by MV Cyano may have some kind of algae to report it to the town’s board of health.

Yellow alerts are common for ponds in the summer, Reddington said. “It just means that cyanobacteria are present, they are measurable. There’s always some risk for a dog, or a jump in the water. Yellow is a normal thing that you often see in summer ponds. It’s just a ‘use some caution,’” Reddington explained. 

“Orange indicates numbers have come up and that there is a potential harmful algal bloom,” also called a HAB for short, Reddington said. “If they continue to rise it could go to an advisory. It’s telling you that the concentration of cyanobacteria has increased enough to use more caution.” 

“The only one that says no swimming is the red,” said Reddington, the HABs advisory, but she says in scenarios involving HABs, it’s all about individual risk tolerance. 

“These are advisories,” said Emily. “No handcuffs.” 

If walking a dog along a pond with a HABs alert, watch, or advisory, be sure to prevent the dog from drinking the water, as cyanotoxins become more dangerous when ingested. While human disease resulting from HABs is rare, known effects of ingesting cyanotoxins involve neurological problems, with select studies examining a speculative link between HABs and ALS. 

These toxins are only of concern when present in high concentrations, but shellfish grown in waters experiencing cyanobacteria blooms or alerts should not be consumed. If pond water is visibly bright green, or if there is any sign of a bloom, it is recommended to avoid swimming and avoid eating seafood harvested from the pond until testing confirms toxin levels are safe. Oysters, blue crabs, soft-shell clams, and other shellfish are harvested en masse from ponds around the Island. “The shellfish industry is really important economically and also culturally,” acknowledged Reddington.

While cyanobacteria and toxic blooms may be natural, and nothing new, Reddington and Bouck’s mission with MV Cyano is to help keep these dynamic ecosystems in a state of healthy balance. 

“Last month, July, was the hottest month on record, globally,” says Reddington. “The things that drive blooms are imbalance in the ecosystem, like when it’s super-hot and there’s too much nitrogen or phosphorus feeding the ponds. The more nitrogen and phosphorus we put in the water, and the warmer the temperature, the more likely we are to see future blooms.” 

In partnership with Falmouth’s Marine Biological Lab, MV Cyano tested four Island ponds using technology that allowed researchers to determine the source of nitrogen, be it naturally occurring or originating from wastewater or fertilizer runoff. 

“You can actually tell by the nutrient sample where the nitrogen is coming from, and that percentage,” said Reddington. 

Of the four ponds studied on the Island, more than 50 percent of the nitrogen came from wastewater. The next greatest contributor was fertilizer and other human-introduced nitrogen sources, according to Reddington and the MBL study. 

“This has been a large discussion in the state of Massachusetts and the Cape specifically, what to do about this nitrogen problem,” said Bouck. “A lot of it comes from wastewater, and probably the majority of that is from septic leach fields and septic tanks.”

Because MV Cyano has only been monitoring the ponds for three years, Bouck and Reddington could not comment on any trend indicating increased toxic blooms. They did have some recommendations about things the community could do to lessen the amount of phosphorus and nitrogen humans contribute to the ecosystem. 

“The simplest thing that we know will help is to stop using fertilizer,” said Reddington. “But that has to be homeowners, that has to be landscapers, that has to be a lot of people choosing not to use fertilizer,” she said, a potentially big ask for the Island’s landscaping and agricultural economies. 

When it comes to mitigating nitrogen in wastewater runoff, Bouck has been researching innovative alternative systems and technologies that the Island could adopt. 

“There are many different setups for many different kinds of homes,” he said. 

Bouck explained that filters can be installed in septic tanks that remove nitrogen from the water before it can make it into the groundwater, decreasing the amount of nitrogen entering water bodies downstream. 

“Ammonium or nitrate are harmful to ponds; those are forms of nitrogen,” Reddington said. “But this converter converts it to nitrogen gas, which is already plentiful in the air. The goal is to transform harmful nitrogen into harmless nitrogen.” 

Expanding wastewater treatment plants could also be a good strategy, as Reddington says they are particularly good at removing nitrogen and phosphorus from the water. 

“It may be easier and more affordable in the long run to do that than to change every single individual septic system in a neighborhood, but it depends on the community,” said Bouck, when speaking of possible future solutions. 

Reddington commented on the town of Tisbury’s water treatment plans, calling them “innovative in putting forward different solutions and working to get regulations in place and systems tested.” 

“It’s not required right now on the Island, but it’s probably needed. You can see these blooms are happening,” said Reddington. 

Reddington and Bouck say there is no one-size-fits-all solution to this problem, should the Island community and towns choose to tackle it. “It’s going to have to be unique to the community, to the watershed, and to the pond itself. That’s why it’s so important to collect this environmental data,” said Reddington. 

“There’s a lot of beautiful water here we want to protect,” she said.