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CNY OUTDOORS
Adirondack lakes are turning browner, warmer, and less oxygenated according to a new study by researchers at Cornell University.
The phenomenon, known as “lake browning,” has dark implications for cold-water fish species central to the Adirondack region’s identity and economy, particularly brook trout, the official New York State fish.
Brook trout prefer cold, well-oxygenated water, which is why they’re most often found in fast running streams and rivers amply shaded by trees. New York is one of only two states—the other being Maine—with lakes that support wild brook trout populations.
But if current warming and browning trends continue, 95% of Adirondack lakes won’t support brook trout populations in the near future, said Stephen Jane, lead author of the study and a post-doctoral fellow at Cornell’s Atkinson Center for Sustainability from 2021-23.
“It may not take a whole lot of warming or browning to really put fish into a real squeeze,” he said. “If it’s bad enough they’re just not going to be able to survive.”
Most Adirondack lakes have a sepia tint similar to weak tea, a byproduct of dissolved organic matter leaching into aquatic systems from the surrounding landscape. Think of it as tea brewed from leaves decaying on the forest floor.
“Just like you put a tea bag in a cup of water and the water becomes brown, it’s the same concept,” Jane said. “The brown water that becomes tea is dissolved organic matter.”
Lake browning is an accelerated version of this otherwise natural process. Let a tea bag steep too long and you get a darker brew. That brown water traps heat at the surface and prevents light from penetrating into the water column, expanding the volume of cool water near the bottom.
The result is lakes divided into hot and cold zones that don’t mix. Oxygen can’t reach lower depths. That’s bad for brook trout, Atlantic salmon, and other cold-water fish species. Surface waters become too hot, and deep water has no oxygen, forcing fish to seek refuge somewhere in the shrinking middle.
Jane calls this dynamic “the oxythermal squeeze” and estimates that about half of all Adirondack lakes already contain no hospitable zone for brook trout in late summer.
Jane found that deep lakes over 30 meters seem to be resistant to both warming and browning, but they’re extremely rare. Less than one percent of Adirondack lakes fall into this category, he says.
“The best-case scenario for Adirondack brook trout is to be in one of the 1% of lakes that are big and deep and well-oxygenated all the way to the bottom. Most fish are not that lucky,” said Peter McIntyre, an aquatic biologist at Cornell. “They’re in the other 99% of the lakes that show these browning trends.”
Apart from a handful of deepwater lakes, researchers determined that less than five percent of Adirondack lakes host a hospitable zone for brook trout year-round. And that zone is typically no thicker than five feet during the warm season.
“If the inhospitable layers touch at some point, then you’re likely to see some mortality of the fish,” said McIntyre.
Evidence shows that climate change is super charging the problem by prolonging the time period that lake bottoms remain anoxic, and by flushing ever more organic matter into lakes through extreme precipitation events—like pouring hot water on a tea bag.
“Currently [brook trout] are hanging on,” Jane said, “but they’re certainly going to get squeezed into a smaller and smaller space, and that’s going to likely reduce populations sizes.”
When scientists began studying the impact of air pollution on Northeast ecosystems in the 1970s, the public was confronted with alarming images of denuded Adirondack forests and crystal-clear mountain lakes bleached of all life.
The phenomenon had a sinister name: acid rain. If you thought the problem of acid rain was solved decades ago, you’d be half right.
Amendments to the Clean Air Act in 1990 greatly curtailed pollutants that caused acid rain. Ecosystems began to recover. Once dead Adirondack lakes came back to life and regained their natural sepia hue.
What scientists didn’t fully understand until now is that acid rain had altered the region’s soil chemistry, causing dissolved organic matter—the stuff inside the tea bag—to leach into aquatic systems at very high levels.
Researchers might have overlooked lake browning altogether if Jane and his team hadn’t dropped high frequency oxygen sensors into 15 remote Adirondack lakes in the spring of 2021 to explore another legacy of acid rain: mercury contamination.
“It quickly became obvious that several of the lakes had extensive anoxia,” Jane said.
Jane’s sensors revealed for the first time the full extent of a problem that had been growing unnoticed for decades and has no end in sight.
“These sorts of processes never continue forever,” said McIntyre. “It’ll be reined in at some point, but we have no idea what that point will be.”
www.syracuse.com
Lakes in the Adirondacks are getting browner. Here’s why that’s bad.
Adirondack lakes are turning browner, warmer, and less oxygenated according to a new study by researchers at Cornell University.
The phenomenon, known as “lake browning,” has dark implications for cold-water fish species central to the Adirondack region’s identity and economy, particularly brook trout, the official New York State fish.
Brook trout prefer cold, well-oxygenated water, which is why they’re most often found in fast running streams and rivers amply shaded by trees. New York is one of only two states—the other being Maine—with lakes that support wild brook trout populations.
But if current warming and browning trends continue, 95% of Adirondack lakes won’t support brook trout populations in the near future, said Stephen Jane, lead author of the study and a post-doctoral fellow at Cornell’s Atkinson Center for Sustainability from 2021-23.
“It may not take a whole lot of warming or browning to really put fish into a real squeeze,” he said. “If it’s bad enough they’re just not going to be able to survive.”
Most Adirondack lakes have a sepia tint similar to weak tea, a byproduct of dissolved organic matter leaching into aquatic systems from the surrounding landscape. Think of it as tea brewed from leaves decaying on the forest floor.
“Just like you put a tea bag in a cup of water and the water becomes brown, it’s the same concept,” Jane said. “The brown water that becomes tea is dissolved organic matter.”
Lake browning is an accelerated version of this otherwise natural process. Let a tea bag steep too long and you get a darker brew. That brown water traps heat at the surface and prevents light from penetrating into the water column, expanding the volume of cool water near the bottom.
The result is lakes divided into hot and cold zones that don’t mix. Oxygen can’t reach lower depths. That’s bad for brook trout, Atlantic salmon, and other cold-water fish species. Surface waters become too hot, and deep water has no oxygen, forcing fish to seek refuge somewhere in the shrinking middle.
Jane calls this dynamic “the oxythermal squeeze” and estimates that about half of all Adirondack lakes already contain no hospitable zone for brook trout in late summer.
Jane found that deep lakes over 30 meters seem to be resistant to both warming and browning, but they’re extremely rare. Less than one percent of Adirondack lakes fall into this category, he says.
“The best-case scenario for Adirondack brook trout is to be in one of the 1% of lakes that are big and deep and well-oxygenated all the way to the bottom. Most fish are not that lucky,” said Peter McIntyre, an aquatic biologist at Cornell. “They’re in the other 99% of the lakes that show these browning trends.”
Apart from a handful of deepwater lakes, researchers determined that less than five percent of Adirondack lakes host a hospitable zone for brook trout year-round. And that zone is typically no thicker than five feet during the warm season.
“If the inhospitable layers touch at some point, then you’re likely to see some mortality of the fish,” said McIntyre.
Evidence shows that climate change is super charging the problem by prolonging the time period that lake bottoms remain anoxic, and by flushing ever more organic matter into lakes through extreme precipitation events—like pouring hot water on a tea bag.
“Currently [brook trout] are hanging on,” Jane said, “but they’re certainly going to get squeezed into a smaller and smaller space, and that’s going to likely reduce populations sizes.”
When scientists began studying the impact of air pollution on Northeast ecosystems in the 1970s, the public was confronted with alarming images of denuded Adirondack forests and crystal-clear mountain lakes bleached of all life.
The phenomenon had a sinister name: acid rain. If you thought the problem of acid rain was solved decades ago, you’d be half right.
Amendments to the Clean Air Act in 1990 greatly curtailed pollutants that caused acid rain. Ecosystems began to recover. Once dead Adirondack lakes came back to life and regained their natural sepia hue.
What scientists didn’t fully understand until now is that acid rain had altered the region’s soil chemistry, causing dissolved organic matter—the stuff inside the tea bag—to leach into aquatic systems at very high levels.
Researchers might have overlooked lake browning altogether if Jane and his team hadn’t dropped high frequency oxygen sensors into 15 remote Adirondack lakes in the spring of 2021 to explore another legacy of acid rain: mercury contamination.
“It quickly became obvious that several of the lakes had extensive anoxia,” Jane said.
Jane’s sensors revealed for the first time the full extent of a problem that had been growing unnoticed for decades and has no end in sight.
“These sorts of processes never continue forever,” said McIntyre. “It’ll be reined in at some point, but we have no idea what that point will be.”
Lakes in the Adirondacks are getting browner. Here’s why that’s bad.
Adirondack brook trout populations threatened by lake browning, warming, new study says
www.syracuse.com
