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Algae blooms are a recurring problem in the Chowan River Basin, but excess nutrients are being triggered more and more, including those deemed harmful or toxic, but scientists are not sure exactly why.
By Catherine Kozak
Stresses on the environment may be unnoticeable for a while, but eventually natural imbalances will become evident.
In the calm, fresh waters of the Chowan River Basin, the unhealthy water quality is all too well exemplified during the summer by blooms of blue-green algae, whether they crawl along the shore or explode from one shore to another.
“They were really bad in 2015,” said Colleen Karl, president of theChowan Edenton Environmental Group, or CEEG. “It started in Edenton Bay. The water was turquoise.
Algae, which are photosynthetic microorganisms, are natural inhabitants of waterways. But when conditions are out of balance, they can quickly multiply into harmful algal blooms.
Until six years ago, the Chowan River and creeks had not had significant blooms since the 1970s, which were related to releases from a paper manufacturer. The problem with algae blooms this time around has persisted, but no one knows exactly what triggers them, beyond the unhealthy amounts of nutrients.
“We know the nitrogen levels are very high,” Karl said. “The big question now is that we don’t know enough because these are fueled by so many different things.”
And flowers are now starting to appear in new places in the Little, Perquimans, and Pasquotank rivers and their tributaries.
Some culprits could be leaks from septic tanks, fertilizer or animal feed, Karl said, but whatever the source, the problem is being exacerbated by warming waters and rising waters due to climate change. .
“It seems there are more flowers after the rains,” she said. “But the trick is there. The biomass is there. It doesn’t take much for these to explode.
The North Carolina Department of Environmental Quality issued a notice on August 2 warning the public to avoid contact with blue or green water from Arrowhead Beach to Rockyhock in Chowan County and Colerain in Bertie County.
The state determined that the bloom was dominated by cyanobacteria, known as blue-green algae which can contain toxins and create health risks to humans and animals, including liver damage. Not only are swimming and boating dangerous, health officials say, any skin exposure should be rinsed off with soap and water as soon as possible.
Karl has said more than once that she has observed people kayaking and canoeing in waterways filled with algae.
A recent bloom at Bennett’s Millpond has formed green mats of algae that have covered the surface.
“Know that this body of water is full of blue-green algae which may or may not be toxic,” Karl posted on September 1 on the CEEG’s Facebook page. “The smell of degrading seaweed was strong even though we were all wearing N95 masks. It is heartbreaking to see our beautiful waterways in this state.
Risks to human health
The health effects of blooms are not fully understood, including the short- and long-term dangers of certain levels of exposure to certain toxins in algae. For example, an algae bloom has been cited as a possible cause of therecent mysterious deaths near Yosemite National Park of a family of hikers and their dog.
Little is known about the health effects of breathing airborne cyanobacterial toxins, said Haley Plaas, a doctoral student in environmental science and engineering at the Chapel Hill Institute of Marine Sciences. the University of North Carolina at Morehead City, in a recent interview.
Plaas, who has been researching the effects of aerosols since 2020, said Karl and other community scientists at CEEG have helped provide study sites and water samples of blooms. In fact, she said she traveled to Bennett’s Millpond in late August to take water and air samples.
New equipment, an odd-looking 4½-foot-tall steel body with a mushroom-shaped head, was deployed on private property to collect the aerosol particles. In addition to writing a manuscript on his work in a peer-reviewed journal, Plaas said the data will be analyzed to determine details such as the identity and concentration of toxins, and what environmental factors may have contributed to Her presence. In addition, the raw data will be published in an open source database.
All kinds of algae are known to create toxins, she said, or harmful algal blooms, although not all algae blooms are toxic. As the data only goes back 30 years, Plaas said, it is not yet known whether algae blooms are becoming more toxic.
In general, blooms are increasing worldwide not only because of the warming associated with climate change, but also because there is more nutrient pollution. Researchers hypothesize that one of the reasons for Chowan blooms could be linked to changes in land use that have reduced swamps and wetlands – riparian buffers – that would otherwise be there to suck up the wetlands. excess nutrients.
The sources of the nutrients can be difficult to identify, let alone control, said Plaas, and there is also a lack of epidemiological research into the damage caused by toxic algal blooms, in part because it is so difficult. to do.
“Basically, you can be exposed to these toxins by swimming in water, eating food (like fish), drinking water, or inhaling it,” she said. “People in North Carolina are most likely exposed to recreational activities. “
But the symptoms – nausea, vomiting, rashes – overlap with symptoms associated with many other illnesses.
“By the time someone gets sick, it can be two or three days after exposure. Then it can happen seven days after exposure when a doctor rules out other causes, ”she said. Then there is the complication of collecting the sample and testing it. Since the flowers can not only move, they can come and go before anyone has a chance to take a sample, and there are no staff available to sample and test every flower in such a large condition. than North Carolina.
Research is underway to develop a real-time sensor, she said. But in the meantime, there’s a networking system that includes cellphone apps and community scientists who report blooms and take samples when possible. There are also digital tools for monitoring and mapping harmful algal blooms.
With algal blooms becoming a growing concern globally, recurring blooms in the Chowan River have garnered more attention from the scientific community.
Part of the Albemarle-Pamlico estuarine system, the second largest in the country behind the Chesapeake, the waters of the Chowan Basin are referred to as nutrient sensitive waters, because of the way they empty and drain.
The Chowan River Basin Water Resources Plan 2021was approved in March by the State Environmental Management Commission. Basin plans are required by state law and approved every 10 years by the commission. Among the plan’s priorities is managing and / or reducing recurring algal blooms in the region, which will require more data collection and review, said Anna Gurney, spokesperson for the Quality Division. of water, in response to Coastal Review.
Implementation of the plan will involve interstate cooperation and best management practices to reduce the amount of nutrients entering the system, such as wastewater and stormwater. Another important part of the plan is public engagement.
“Communicating the science will spark interest and action to protect water resources,” Gurney wrote, adding that several basin stakeholders are already involved in the effort.
“Northeastern North Carolina, like many other parts of the state, works with limited resources; however, people are passionate! DEQ / DWR Basin Planner Forest Shepherd said in an email. “Citizens are concerned about their waters and have expressed this in the multiple letters of public comment we received during the development of the Chowan and Pasquotank River Basin Water Resources Plans. These plans are tools to help with education, awareness and public engagement; which is vital for the successful protection of these water resources.
Karl, who has a background in science, said she saw the need for a lot more communication with the public, as evidenced by the people she saw fishing and boating at Bennett’s Millpond.
“Literally the water was pea green,” she said. “Where were the signs? Not many people know what these toxins can do.
The county has not posted any warning about the overgrowth on its website, Karl said, and the water resources press release is limited in scope.
“Who sees this? ” she asked. “Unfortunately, we have no way of getting the word out.”
Although she credited the progress of researchers and officials in North Carolina, Karl said everyone is scattered and under-resourced. New York is an example of a state doing a better job of networking and reporting blooms, as well as using citizen scientists, she said.
“They seem to be able to get the word out more widely,” Karl said. “You need people. It takes money.
This is the third in a series of multi-part special reports on coastal water quality.Read more.
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