ACADIA NATIONAL PARK, Maine — Ask someone to name the first lake to appear in Maine thousands of years ago and you’d likely get answers like Moosehead or Sebago. Few would guess the answer is very likely Sargent Mountain Pond.
It is neither the largest nor the most easily reached nor the most popular body of fresh water in the state. Nor are motors allowed on the pond, and there are no launch facilities.
According to recent research at the University of Maine earth sciences department and the Climate Change Institute, the small, shallow pond near the top of Sargent Mountain within the borders of Acadia National Park is a prime candidate for the title of Maine’s First Lake.
“You can’t really say it’s the first without checking them all,” said Stephen Norton, professor emeritus at the Climate Change Institute. “But if I had to guess, I’d say that Sargent Mountain Pond is probably the first one.”
Norton led a team of researchers who studied the history of the lake, which goes back nearly 17,000 years as the last ice age was waning. At that time, the great ice sheet that had covered much of North America was wasting away and nunataks — an Inuit term for isolated rock outcroppings — began to appear in the ice that still encased what is now Mount Desert Island.
“Cadillac Mountain, Dorr Mountain, Sargent Mountain would have peeked up through the ice,” Norton said this week.
Sargent Mountain, at 1,373 feet, is the second-tallest peak in the park and would have been one of the first areas of Maine to become ice-free. While there are taller mountains and lakes at higher elevations in Maine, they are all inland and at that time still would have been covered in ice, according to Norton. Even Mount Katahdin was still under ice at that time, as was the Maine coast.
As the upper levels of Sargent Mountain became ice-free, the lake began to form, and because the rest of Maine was still in the deep freeze, the body of water became, apparently, Maine’s first lake.
Almost as soon as the lake formed, sediment began to be deposited on the lake bottom. That sediment was the focus of the team’s research, which began in 2007, according to Norton.
“Three years ago, we took a core of sediment — about 5 meters of sediment — that represents a 16,600-year record of what was going on in the water and watershed,” Norton said.
Over the next two years, researchers studied the core and gathered evidence about vegetation, soil, climate and water chemistry, working up from the oldest layer of sediment to the current lake bottom.
According to Norton, the research provided insight into the workings of the lake. Among their different studies, researchers examined the remains of diatoms, single-celled algae that live in communities and change their communal structure in response to changes in water chemistry.
Based on the evidence of the diatoms found in the sediment core, team member professor Jasmine Saros determined that about 11,000 to 12,000 years ago there was a dramatic change in the water chemistry in Sargent Mountain Pond. That corresponds to the growth of trees in the watershed about 12,000 years ago, according to professor George Jacobson, another team member. Until then, much of the emerging land in what is now Maine had been tundra.
With the proliferation of trees came forest debris which, as the leaves and branches decomposed, created dissolved organic carbon. Through a complex system of chemical bonding, the organic carbon has the ability to dissolve aluminum from the soil. As the aluminum was transported into the lake, precipitated, and moved through the water column, it stripped phosphorus from the water.
Phosphorus is a nutrient that promotes growth in freshwater lakes, and the depletion of it at Sargent Mountain Pond turned what had been a productive lake into an unproductive one, with “less algae and fewer critters.”
“For the first 5,000 years of its life, it was a very productive lake,” he said. “Then, as the result of the arrival of trees, there was a change in the productivity of the lake.”
The research also showed that a cold snap about 10,000 years ago slowed the growth of trees in the region and halted that process for a while.
“The climate of the Earth got dramatically colder,” Norton said. “The cold snap — which lasted about 1,000 years — shut down that process temporarily. When the Earth began to warm up again, the forests got going, and the process commenced again and has continued to today.”
Through the study of this old, small pond — which may be the first of Maine’s many lakes — researchers have discovered a naturally recurring system through which a lake changes from productive to unproductive, Norton said.
“This has been a nice case study of the co-evolution of climate, vegetation, soil and lake water chemistry,” he said.
Those findings may be useful to agencies that monitor development close to Maine’s lakes and ponds, particularly if they are concerned about the amounts of phosphorus that might enter those water bodies from human sources.
That, however, is outside Norton’s purview.
“I was just an old scientist interested in finding answers to questions,” he said.
Norton has spent the past year preparing a report on the team’s findings from Sargent Mountain Pond. He is editing the final manuscript that will be submitted to the Journal of Paleolimnology.
Information about the University of Maine Climate Change Institute is available at www.climatechange.umaine.edu.