BURLINGTON — Pete Stangel, an aquatic biologist with the state, has sampled Lake Champlain’s waters for over two decades. But this year he’s out looking for something different than in years past: cyanobacteria DNA.
Stangel, along with environmental technician Kelcie Bean and US Geological Service microbial ecologist Charlie Culbertson, were taking water samples out past the breakwater in Burlington Bay on a choppy Tuesday morning.
Nutrient runoff and climate change are creating ideal conditions for headline-grabbing cyanobacteria blooms in freshwater bodies. Culbertson, who is based in Maine, said that "the frequency and intensity of blooms is on the rise” in New England.
Scientists have been using the relatively new technique of analyzing free floating DNA in soil and water samples, called environmental DNA, to take a rapid biodiversity assessment. Culbertson is leading a USGS study taking environmental DNA samples in Lake Champlain and ponds in southern Maine and Cape Cod to provide a “snapshot” of what microbial communities are present in different water conditions.
Scientists are still trying to understand what triggers toxic cyanobacterial blooms. While there are many cyanobacteria species, not all of them release toxins and and even those that do only do so at certain times, said Culbertson.
“For us, just because a bloom is out here and it’s cyanobacteria does not mean it’s harmful, right?” he said. “Until it starts causing some sort of ecosystem reaction, and that can be toxin production, it can be taste and odor issues, or skin irritations.”
However, the blooms can produce substances that are “highly toxic,” he added. In the short term, exposure to cyanotoxins can lead to fever, headaches, skin irritations and diarrhea. In severe cases, exposure to certain cyanotoxins can lead to liver or kidney damage.
Culbertson hopes the DNA sampling research will provide a “predictive tool” to see the changes in microbial communities leading up to toxic cyanobacteria blooms.
Out on the water in Burlington, Stangel took a water sample using a stainless steel tube called a Kemmerer in the same vein as a glaciologist sampling an ice core. He dumped the sample into a churn splitter bucket and Culbertson turned a spigot on a bucket to fill up a plastic syringe with some of the water sample.
Bean pushed the sample through a filter to capture DNA from fish, phytoplankton, and bacteria on a small piece of paper. Culbertson placed the filter in a dry ice cooler to keep it frozen until it arrived at the University of New Hampshire’s genomics center.
“It’s kind of like CSI Champlain,” joked Bean.
The researchers adroitly collected their usual array of water samples — pH, zebra mussel larvae, chlorophyll pigments — in the lurching boat. By combining the DNA analysis with long-term water quality monitoring data, they hope to better understand what lake conditions lead to toxic cyanobacteria blooms.
Angela Shambaugh, acting director of the state Department of Environmental Conservation’s lakes and ponds program, said that the new research should provide “an opportunity to get a better understanding of what (cyanobacteria) communities are out there.”
The state currently analyzes some cyanobacteria samples with a microscope, but the environmental DNA sampling uses larger water samples, which could allow them to detect species present in smaller amounts.
Early season cyanobacteria blooms reported in Vermont and New York as part of the state’s cyanobacteria tracking program were at an all time high this year. Shambaugh said the increased reporting in Vermont is likely a combination of more public awareness of the blooms and climate change, which has led to warmer waters in the spring and fall.
“These are living organisms and so they change very rapidly in response to water conditions,” said Shambaugh. “And there are very few techniques that can offer instantaneous turnaround that can confirm cyanobacteria.”
She added that while the swimming season may be over, duck hunters need to be aware that their dogs still could be at risk as cyanobacteria blooms can still occur for a few more weeks.
Don't miss a thing. Sign up here to get VTDigger's weekly email on the energy industry and the environment.