trout

A combination of the warming climate and the phenomenon of lake browning are making the bottom of most lakes in New York’s Adirondack Mountains unlivable for cold water fish – such as trout, salmon, and whitefish – in the summer.

Lake browning occurs when dissolved organic matter from forests turns the water tea-brown. Browning is the legacy of a century of acid rain and subsequently the fact that forest soils have suffered reduced capacity to absorb weak organic acids, leading to more dissolved plant matter flowing into lakes. Climate change has increased the frequency of extreme precipitation events and the length of growing seasons, leading to more runoff of organic matter.

Browner water traps more of the sun’s heat at the top of the lake and blocks the sun’s rays from reaching deeper. The result of the browning is lakes that are either too warm or too deoxygenated to support trout populations.

A study of 1,467 Adirondack lakes by Cornell University researchers found that only about 5% of them may continue to maintain water that is cold and oxygenated enough to support cold-water fish.

Deeper lakes fare much better because they have so much water that their oxygen is hard to deplete, but only 1% of all Adirondack lakes are deeper than 30 meters. Another 4% are very clear because the influx of cold water outpaces the expansion of low-oxygen zones and limits the effects of browning.

The study urges the protection of as many lakes as possible from species invasions, nutrient and salt pollution, and other forms of environmental degradation.

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Most Adirondack lakes will likely become unsuitable for trout

Photo, posted July 17, 2011, courtesy of Lida via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Highway accidents involving animals are a big problem for both people and animals. About 200 people die every year in the U.S. as a result of collisions with animals. In total, one to two million large animals are killed by motorists every year. And these crashes are expensive: deer-car collisions cost an average of more than $8,000 each; elk-vehicle collisions about $25,000; and moose-vehicle collisions over $44,000.

In the United States, there are 21 threatened and endangered species whose very survival is threatened by road mortalities. These include Key deer in Florida, bighorn sheep in California, and red-bellied turtles in Alabama.

One solution that has been quite effective around the world in reducing car-animal collisions is wildlife overpasses and underpasses. Crossings and fencing that guide animals over or under highways reduce collisions by 85-95%.

These traffic-spanning bridges and tunnels have been popular in Europe since the 1950s. The overpasses usually look much like regular overpasses for cars but are decked out with native flora. The underpasses, which assist shyer and smaller animals, are typically invisible to drivers.

Washington State has recently started building wildlife bridges and underpasses on Interstate 90. These passes will allow elk, black bears, mountain lions, pika, and even trout to traverse what was once a near-impenetrable barrier of road.

Some animals that are accustomed to human structures start using the crossings almost immediately. For others, there is learning curve. As in many things, the early adapters are important as they provide paths and model behavior that more reticent animals learn to follow.

Wildlife bridges are a very good thing for wildlife and for people.

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How wildlife bridges over highways make animals—and people—safer

Photo, posted July 22, 2017, courtesy of David Fulmer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Adirondack lakes becoming inhospitable for trout

A combination of the warming climate and the phenomenon of lake browning are making the bottom of most lakes in New York’s Adirondack Mountains unlivable for cold water fish – such as trout, salmon, and whitefish – in the summer.

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Wildlife Bridges

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