While visiting Vermont in late July, I took a day to catch up with colleagues who are studying lakes. University of Vermont (UVM) Rubenstein Ecosystem Science Laboratory director Jason Stockwell arranged for me to go out on a sampling run with two interns. Our destination was Shelburne Pond, a shallow lake located about ten miles south of Burlington. The hyper-eutrophic lake was the subject of my undergraduate thesis research, “Internal Sources of Phosphorus in Shelburne Pond, Vermont.” I was interested to learn about the latest round of research there and invited college friends Jennifer Curtin and Sara Thompson to join me for the outing.
A large frontal system had moved through the day before, leaving behind a quintessential Vermont summer day: clear skies with air temperatures in the 70s. Puffy white clouds floated by. It was not unlike the day I arrived in 1985 as a geology student to collect samples and discovered that a massive fish kill had occurred the night before.
A Tipping Point: Massive Fish Kill in the mid-1980s
On that day over a quarter century ago, thousands of fish were floating belly-up, perch, walleye and northern pike alike. A few were gasping for breath at the surface. The event had occurred so recently that the stench of rotting carcasses had yet to develop on that late summer morning. It smelled more like a busy, outdoor fish market than an idyllic natural lake. I suited up in my wetsuit and scuba tank, and with dead fish swirling all around me, plunged to the murky depths. My advisor Jack Drake reminded me that it would be an important data point, so in I went.
Shortly after arriving at the boat launch this summer, a fisherman arrived to launch his boat. With the help of Jennifer, an environmental lawyer, we soon realized that he and I had stood together on this same shore nearly 30 years earlier. He, too, had been on Shelburne Pond the day of that fish kill.
Jon Kruger, an outdoorsy 68-year-old who lives in Milton, has been fishing on the lake since he was eleven years old, he told me. When he was a boy, he could rent a rowboat from a vendor on the lake and go out fishing just miles from his home. He caught a lot of pumpkin seeds, a common sunfish. “In the 1960s and 1970s, the lake was a premier walleye fishery,” he said. “It was good up until the big fish kill in 1985.”
We reminisced about the causes of the fish kill. He reminded me of the allegations about a now defunct cheese factory dumping whey in a stream flowing into the lake. I recounted how, after a period of warm weather and calm winds, the massive algae bloom died off suddenly when a cold front passed through. The process of decomposition consumed the dissolved oxygen fish need to breath.
The Vermont Fish and Wildlife Department tried to restock the walleye, but the fishery never recovered, Kruger told me. “I’ve caught only one walleye from the lake since then,” he said. Smaller fish kills have returned in recent years, the most significant occurring in 2009, but nothing on the scale of the event in the 1980s.
Scientists refer to these dramatic changes as “regime shifts,” when an ecosystem reaches a threshold or tipping point beyond which it is forever changed. With climate change already upon us, including greater climate variability, this is a subject of great interest for ecologists.
New Era of Lake Research Begins: Big Data and Global Collaboration
Lab director Stockwell is leading a new research program on Shelburne Pond to study just this sort of phenomena. He was inspired to bring a “smart” data buoy into the mix after we attended a meeting of the Global Lake Ecological Observatory Network (GLEON) in Argentina last year. He secured funding and contracted with Greensea Systems to design and construct a buoy with automated sensors using an “open source” approach. The buoy was deployed for testing in the fall and should be fully operational next year.
I asked Stockwell, who is also busy directing a research program on Lake Champlain, why he chose Shelburne Pond. “Getting classes and student researchers out on Champlain is expensive and involves more weather considerations. Shelburne Pond is close to campus and inexpensive to sample, relatively speaking. It’s also a UVM Natural Area, and we’ve been looking for ways to make better use of these areas,” he said.
Lakes are dynamic and constantly changing ecosystems. The approach that I used as a student of sampling every week or two is no longer enough. This is where automated sensors mounted on a buoy can make a difference. By collecting data on multiple parameters every 15 minutes, the sensors provide high frequency data. When combined with a field sampling program, this allows Stockwell and his students to better understand environmental changes in the lake.
It helps that the lake is well studied, Stockwell told me. Some of the earlier research, including mine, provides context for the current “big data” approach. In addition to past studies, researchers will be able to compare their results with those from Mississquoi Bay on Lake Champlain. Although larger than Shelburne Pond, the bay shares similar characteristics, and the Research on Adaption to Climate Change (RACC) project is conducting similar studies. And because the research project is linked in with GLEON, Stockwell’s team will also be able to compare their data with other lakes around the world and collaborate on global studies already underway.
One of those studies is called “Spring Blitz” and another is called “Storm Blitz.” GLEON scientists are researching what happens to phytoplankton diversity during periods of dynamic change, including after ice-out, when lake ice melts in spring, and after major storm events. Stockwell and his students began sampling the lake through the ice and continued twice a week late into the spring and weekly throughout the summer and fall. Shelburne Pond was one of two lakes participating in the study this year. The other lake was in Ontario, adding to the ten lakes that participated in the global study in 2013.
Harmful Algae Blooms Becoming More Common
On the day we visited Shelburne Pond last summer, my friends and I were in vacation mode, but they were up for any activity that would get us out on the water. I tried to warn them off with tales of fish kills and toxic algae blooms, but to no avail. When we arrived at the lake, the water near shore was bright green with slimy globs floating in it – a sure sign that a blue-green algae bloom was underway. Before I could dissuade them, they had climbed aboard the university’s red, rigid inflatable boat.
Blue-green algae are actually a type of cyanobacteria, microscopic organisms that are one of the earliest life forms found on Earth. Because cyanobacteria can produce toxins, they are sometimes referred to as “toxic algae,” but this is also somewhat of a misnomer because they themselves are not toxic nor do they produce toxins at all times. Cyanobacteria are not all bad either. Because they can fix nitrogen and produce oxygen, they are responsible for creating the air we breath.
UVM junior Brad Roy led our excursion, carefully issuing instructions on safety procedures and insisting that we wear the fluorescent yellow life jackets. Tall, clean-cut and wearing the requisite baseball cap and rubber boots of a field scientist, he is a Vermonter from Waterbury and the first generation in his family to attend college. Brad displayed an enthusiasm for environmental research that was more like the graduate students I know. It took me two years to declare a major in college, but he has known that he wanted to study fisheries biology at UVM since doing an independent study with the Vermont Fish and Wildlife Department as a high school student. That’s pretty specific for a guy who had never visited the campus, just over 30 minutes from his childhood home, until enrolling as a student.
Némesis Ortiz Declet, a Vermont EPSCOR intern and senior at the University of Puerto Rico, was the other field assistant that day. Quieter but equally serious about her research, she was outfitted the same as Roy, minus the baseball cap. She was collecting data for a study of blue-green algae in Shelburne Pond and Missisquoi Bay. Although the algae blooms had been very active in Shelburne Pond, they had yet to appear in Missisquoi Bay this summer, she told us. “It was bright green when we got here on June 17,” she said. “The surface water temperature has been warmer here than in Missisquoi Bay, so that might be a factor. Another factor is that Missisquoi Bay hasn’t stratified yet this summer, but Shelburne Pond has exhibited weak stratification.”
Lake stratification occurs in warmer months when water forms layers, with warmer surface water on top of cooler, denser water at depth. Stratification affects the physical, chemical and biological characteristics of lakes. With climate warming trends, there is concern about the length of the stratification season becoming longer, creating better growing conditions for the types of harmful algae found in both bodies of water.
It turns out that Missisquoi Bay didn’t escape the blue-green algae blooms, which began in August and continued into September, Stockwell told me. I visited the bay in early November and saw the decaying remnants of algae on the rocky shore.
Out on Shelburne Pond, Ortiz Declet lowered the sonde, a device that contains sensors for simultaneously measuring multiple water quality parameters. It confirmed the presence of blue-green algae, but details about the amounts, specific types and toxin production would require follow-up laboratory analysis. We then used a plankton net to collect samples of microorganisms and a small pump to gather water samples at different depths. We downloaded data from the temperature logger, which is collected from a set of digital thermometers, known as a thermistor chain, suspended between a float on the surface and an 80-pound (36 kilograms) anchor at a water depth of about 15 feet (4.5 meters), the average depth of the lake. We used a Secchi disk, a black and white disk on a string, to measure water transparency. Of the equipment we used that day, only the Secchi disk was the same as I used as a student.
While sampling, we talked about their observations of the algae blooms. On a visit earlier in the summer, they smelled chemical fertilizer, Ortiz Declet recalled. “This was followed by a big storm with lots of rain and then a couple of calm, hot days, causing a giant scum of algae to form on the lake’s surface,” she said. Roy added, “I grew up in rural Vermont and know what fertilizer smells like.” Although based only on anecdotal evidence, they both wondered aloud about the possible connections. They are not the only ones asking this important question.
After helping to collect samples, my friends got distracted with wildlife sightings. Two bald eagles soared overhead. Double crested cormorants flew past, and a flock of Canada geese landed in one of the two large wetlands on the northern shore. We convinced Brad to make a quick side trip to get a closer look. The wetland was teeming with water-loving birds, including a great egret and three great blue herons. It was not difficult to appreciate why the university designated the lake and wetlands as a natural area.
As we motored back to the boat launch, Roy talked about his impressions of Shelburne Pond and the research there. “I had never been here before starting this project. I find the dynamism of the system intriguing. It’s always changing. There is great variability from one week to the next,” he said. “As far as the research goes, I feel like we’re at the cusp of using this technology for new and different kinds of research and data collection. It’s exciting to be a part of that.”
Shelburne Pond played an important role at the beginning of my career, so I couldn’t help but smile while thinking about the next generation of lake scientists and advocates that might emerge from studying this lake and others like it.
Agricultural run-off. Harmful algae. Fish kills. Tipping Points. Climate warming. Extreme weather. These are common themes on lakes around the world. A week after our excursion on Shelburne Pond, news broke about the Toledo water crisis. Jennifer sent me a message soon after. I could tell that she, too, had a new appreciation for how widespread the problem of harmful algae blooms has become and how relevant this type of research is.
I noticed that one of the first actions in response to finding harmful algae in Toledo’s water supply was to install a data buoy near the water intake in Lake Erie. Smart move. Whether for early detection of impaired water bodies, like Lake Erie, or for gaining a more in-depth understanding of the dynamics of aquatic ecosystems where these blooms occur, like Shelburne Pond and Lake Champlain, collecting high frequency data is essential.
When combined with more traditional approaches to lake science, as well as collaboration globally, this new era of research holds great promise for providing information to help address both ongoing and new lake management challenges. “It’s also a great opportunity for undergraduates to receive training in big data and to develop skills in concert with technological advances,” Stockwell said.
Lisa Borre is a lake conservationist, freelance writer and avid sailor. With her husband, she co-founded LakeNet, a world lakes network, and co-wrote a sailing guide called “The Black Sea” based on their voyage there in 2010. A native of the Great Lakes region, she served as coordinator of the Lake Champlain Basin Program in the 1990s. She is now an active member of the Global Lake Ecological Observatory Network.