June 21, 2013

Mission: Examine climate change effects on Maine lakes

Blooms of algae, depletion of fish and reduced ice cover are among the threats posed in Maine.

By MATT HONGOLTZ-HETLING Morning Sentinel

With climate change threatening central Maine's lakes, it is more important than ever to manage the watershed responsibly, say speakers who will discuss the issue during a state conference on lakes and climate change Saturday.

click image to enlarge

Roy Bouchard, a retired lake biologist, in Belgrade on the banks of Long Pond where Great Pond flow into it. Central Maine lakes are particularly susceptible to the threats associated with climate change because they are more heavily populated, and warmer, than the mountainous regions that make up much of the rest of the state, he said.

Staff photo by Michael G. Seaman

The conference, sponsored by the Congress of Lakes Associations, comes just weeks after state lawmakers ordered the Department of Environmental Protection to resume working on a state plan geared toward meeting the challenges posed by a warming planet.

Belgrade resident Roy Bouchard, who retired from his position as a state lake biologist a year ago, is one of several speakers who will discuss the impact of climate change, which he said includes blooms of algae, threats to fish species and less winter ice cover.

"A number of our lakes are right on the edge, places like Great Pond are showing really significant distress," he said.

Central Maine lakes are particularly susceptible to the threats associated with climate change because they are more heavily populated, and warmer, than the mountainous regions that make up much of the rest of the state, he said.

Bouchard said Maine residents must accept that their children will not have the same level of water quality that the previous generations have.

"People buy property saying it's always going to be the same," he said. "That's not true anymore."

Bouchard, whose family has owned a place on Great Pond since the early '60s, said he's been tracking the health of Great Pond and China Lake for 25 years.

In that time, he's seen a growing population in central Maine's lakefront communities put development stress on the watershed.

"In Belgrade, the population has doubled since the '80s," Bouchard said, a far greater rate of growth than in the state as a whole, which increased by roughly 15 percent between 1980 and 2010, according to data from the U.S. Census Bureau.

The water quality has declined in many of the lakes, a trend that Bouchard said will continue.

"The ones that are marginal are going to be stressed," he said. "The ones that are doing OK are going to be marginal."

Bouchard said it's impossible to separate the impact of climate change on a lake from other factors that contribute to the same effects.

He said the effects of climate change are already being felt, and climate change models show that the pace of change will hasten over the next 20 to 30 years.

"The effects are not linear, not a slow creep," he said. "The effects are accelerating."

In the same way scientists track the shrinking of ice at the planet's polar caps, researchers at the U.S. Geological Survey have been carefully combing through historical records to document the annual freezes and thaws of Maine's lakes.

Bouchard said data shows lake surfaces are freezing later and melting earlier, leaving lakes uncovered by ice for as much as a month longer than they were several decades ago.

He said an early ice-out only nudges the average water temperature up by a degree or two, but the impact on the species who live there is massive.

As a lake warms, the water forms distinct layers of different temperature zones, a process called stratification. Every summer, while the lake is warm, the deep, cold layers trapped at the bottom lose their oxygen.

When the period of warm water is prolonged, salmon and trout, which have adapted to live in cold water, lose their habitat.

"They can't breathe," said Bouchard.

Climate change will also increase the likelihood of algal blooms, an undesirable lake condition that can threaten animal and human health, he said.

The absence of oxygen affects the chemical makeup of the water in such a way that phosphorus, a component of fertilizer, is released and feeds the algae that collectively form blooms.

(Continued on page 2)

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