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Lake Researcher Retreat: Climate and DNA were hot topics 

On Friday, January 10th, practitioners and researchers who study lakes and ponds gathered to present recent studies and findings on the shore of Highland Lake in Bridgton. This biennial researcher retreat was hosted by Lakes Environmental Association (LEA) and held at the Highland Lake Resort.  

One of the first presenters was Jeremy Deeds, from the Maine Department of Environmental Protection’s Lake’s Unit.  He gave an overview of a new “Lake Scorecard” that is being developed for the public to better understand lake water quality. This rating system compares and reports on water quality trends, invasive plants, shoreland habitat, and lake vulnerability. The plan is to have the scorecard updated yearly using data collected by other organizations (like LEA) and volunteers across the state.      

Robin Sleith from Bigelow Laboratories talked about some of the methods and challenges in monitoring and assessing toxic cyanobacteria (blue-green algae) in Maine. Currently, toxic blooms are still relatively infrequent in the state and getting bloom samples can be tricky. He said that, so far, most of the blooms in Maine rarely produce enough toxins to be considered a health risk according to the World Health Organization or Environmental Protection Agency. 

Robin then gave an update on the cyanobacteria Gloeotrichia, which has been monitored and studied by several groups across Maine, including LEA.  While other research has indicated that this species can produce the toxin microcystin, it is not usually found in Maine samples. While this is good news, it is still possible that there are toxic strains of this type of cyanobacteria in Maine and more research is being done to assess Gloeotrichia populations across the state.  

Erin Grey from the University of Maine gave an overview of the use of environmental DNA (eDNA) to assess water quality. Unlike traditional DNA testing, which relies on samples taken directly from a plant or animal, eDNA is taken from a sample of water, air, or sediment. Dr. Grey has found that using eDNA to detect invasive mussels in ballast waters in the Great Lakes was more accurate than traditional assessment methodologies. She has also used eDNA to detect invertebrate species in Maine lakes and found patterns by lake but not by depth, indicating that genetic material from these species was well distributed throughout the water column. She also pointed out the utility of using eDNA for the early detection of harmful algal blooms and to assess water quality conditions before and after lake remediation treatments. 

Lucas Bernacki, from Saint Joseph’s College, is also working with eDNA and has been using it to differentiate between invasive plants that look similar to native plants. In particular, he has been using eDNA to distinguish between native and invasive milfoils. 

In a study he completed last year with LEA samples, he looked for evidence of highly invasive Eurasian milfoil in Long Lake and Moose Pond. These two waterbodies were chosen because they both have different species of milfoil (Long Lake has invasive Variable-leaf milfoil and Moose Pond has native Northern Water milfoil).  While these findings are not definitive, his research found no evidence of invasive Eurasian milfoil in either water body.  

Dr. Bernacki is also studying milfoil population genetics before and after control work is completed and developing a method to detect and differentiate invasive swollen bladderwort from native bladderworts in Maine.      

Prior to lunch, attendees separated into three break-out groups to discuss climate impacts and mitigation strategies, freshwater research gaps, and lake monitoring frequency. Some of the takeaways included the need for continuous temperature monitoring of streams, the value of baseline data, interest in studying the impacts of road salt, and a renewed emphasis on the need for traditional conservation practices to protect Maine’s lakes from climate change.   

Portland Water District’s Amanda Pratt presented an assessment of water quality, land use, and land conservation for lakes, ponds, and rivers that drain into Sebago Lake. She noted that these waterbodies are referred to as Sebago’s indirect watershed and make up for 33% of the nutrient load to Sebago. Portland Water District is concerned that problems in lakes that flow to Sebago may be an indicator of what is to come in the larger, downstream Sebago Lake. This assessment used water quality data, long-term trends, and the amount of development and conservation in the watershed and ranked lakes on a 1-5 scale.  

Amanda Gavin from the University of Maine presented her research on changing conditions within mountain lakes during the fall. She began her presentation by stating that, when it comes to lake monitoring, autumn is a “neglected season” and not as well understood as other times of the year. She pointed out that autumn periods are getting shorter and fall temperatures in Maine have increased about 1 degree Celsius since 1998. Her research showed high variability in lake stratification (layering) in the autumn and that ice-on dates do not seem to be related to the onset of lake turnover and mixing.  

Lakes Environmental Association’s Ben Peierls presented a long-term temperature analysis of lakes within LEA’s service area. He noted that some, but not all of the lakes in this area show clear warming trends. Out of the 40 lakes the LEA monitors, 11 showed warming of 0.3 to 0.8 degrees Celsius per decade in summer surface waters since the mid-1980s.  When looking at all the lakes within LEA’s service area combined, Ben found an increase of 0.5 degrees Celsius per decade in summer surface waters. His research did not find any clear relationship between temperature trends and lake size and he noted that monitoring frequency and timing could play a role in trend detection. 

LEA’s 7th wintertime Lake Research Retreat was attended by approximately 50 professionals from universities, colleges, research institutes, non-profits, agencies, and water districts across Maine and New Hampshire.  

By Colin Holme

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