Climate change was the topic of discussion at the Friends of Walker Pond annual meeting last month at Sedgwick Elementary School.
Aquatic biologist and Maine Volunteer Lake Monitoring Program Director Scott Williams talked about the possible effects of climate change on Maine’s lakes and ponds.
“I use the word possible because we don’t know what the effects will be,” said Williams.
One thing is likely, said Williams. As the phenology—timing of natural weather events, such as when ice is out of ponds or how often there are severe storms—changes, it’s unlikely the answers will be good for Maine lakes and ponds.
“People value clarity in lakes most of all,” said Williams. Increasing temperatures, longer warm seasons and more precipitation will likely mean a drop in clarity.
“Last year is a lens of what we can expect,” said Williams. “In 2012, the first eight months were warmer than the historical average, and we received eight inches of rain in a 48 hour period in mid-June.” Decreased ice cover and a longer growing season for biota.
Lakes typically undergo thermal stratification in the summer. This means that as a lake or pond warms, after the spring winds, which mix up the lake’s waters, a layer of cool water forms at the bottom, with a warmer buffer layer and then a layer of very warm surface water. The layers don’t mix during the warmer months, and the lowest and coldest layers may run out of dissolved oxygen. This means cold-water fish may die off during very warm summers.
A warmer pond means problems with algae are more likely as well. “Harmful algal blooms result in an alteration in the lake’s food web,” said Williams. Warmer water and a longer growing season mean an acceleration in growth of native and invasive aquatic plants and an increase in lake color from humic acid.
“The water is likely to be less drinkable and less swimmable,” said Williams. In part, this is due to an increase in blue-green algae, which produce cyanotoxins, which can effect the liver even in low doses.
As an example, Williams cited Lake Auburn, which serves as the drinking water source for the cities of Lewiston and Auburn. Last summer, the lake saw a massive algal bloom and a “substantial die off of lake trout,” said Williams. Scientists are still not sure what caused the problem, and are keeping an eye on it this summer. Figuring out the singular cause of an algal bloom is a bit like searching through a labyrinth, with the specter of invasive plant species looming like a minotaur. Is it increased phosphorous levels due to runoff? Unusual rain events which increase nutrient levels? Symbiotic biota like gleotrichia, suspected to increase other algae levels by 500 or 600 percent?”
“Every lake is unique,” said Williams. “There are so many factors that go into it, the systems are incredibly complex.”
Walker Pond is clear of gleotrichia, said Williams, and has had good readings over the years in terms of clarity and phosphorous. Phosphorous is often a sign of nutrients in a lake ecosystem that can trigger a bloom.
Williams recommends those who are interested in helping preserve the lakes and ponds of Maine join the volunteer lake monitoring program and receive training in how to identify invasive species and other monitoring aspects.
For more information on the program, visit mainevolunteerlakemonitors.org.
Friends of Walker Pond business
After the conclusion of Williams’ talk, the Friends of Walker Pond held its annual meeting. The group discussed public access to the pond, now that the landing is open. President Marilyn Heineman said much of the success of the effort is due to Sedgwick Selectman Nelson Grindal, who long advocated for the access.
“I hope everyone will enjoy it,” said Heineman. The issue now becomes one of maintenance, and helping to ensure that boats participate in voluntary inspections to remove any invasive species that might be on a boat before it is put into the water.
Heineman also spoke briefly about jet skis, which she said are “fun, but loud.” Some are concerned about safety with swimmers and jet skis. Heineman said if jet skis can keep 200 feet from shore to allow for the safety of swimmers and to protect native vegetation, “the jet skis can be a lot of fun for a lot of people.”
Candy Eaton, director of Nichols Day Camp, reported the $5,000 received by the camp sponsored the Swim Club, paying for insurance and promotion of the club. The organization then presented Eaton with another check for $5,000 for next year’s Swim Club.