At one time, Brook Trout Lake in the Adirondacks was full of fish.
That was before the lake’s once pristine waters became too acidic for fish to live in, the result of acid rain.
But after amendments to the federal Clean Air Act went into effect in 1990, the lake began to recover, and several years ago the state Department of Environmental Conversation reintroduced fish to Brook Trout Lake. Sandra Nierzwicki-Bauer, director of the Darrin Fresh Water Institute of Rensselaer Polytechnic Institute, said she believes it’s the first time fish have successfully returned to a lake where all of the fish died because of acid rain.
It may be a sign of things to come.
Researchers at the Darrin Institute in Bolton Landing have been studying 30 lakes in the southwest corner of Adirondack Park, one of the areas most severely impacted by acid rain, since 1994. The idea, Nierzwicki-Bauer said, is to assess how these lakes have fared since the Clean Air Act went into effect. A paper on the topic was published in a recent edition of the scientific journal Applied and Environmental Biology, and a new database contains information available to anyone researching acid rain.
“It’s good information,” said John Sheehan, a spokesman for the Adirondack Council. “It’s an important move forward. We’d like to learn as much as possible.”
So far, 26 of the 30 lakes have shown a decline in acidity, although improvements varied from lake to lake, with factors such as how deep the water is and the steepness of the shoreline having an effect, Nierzwicki-Bauer said. Now there are several other fishless lakes, she said, that would be good candidates for fish reintroduction.
“In general, the fact that we saw an increase in 26 of 30 lakes is pretty good,” Nierzwicki-Bauer said.
Other research has focused on the water chemistry of lakes impacted by acid rain. What made the Darrin Fresh Water Institute project unique is that it looked at water chemistry but also at “biota” — the organisms that make up the food chain in the area being studied. Researchers studied the population of fish and aquatic plants, but also zooplankton, the animal form of plankton, phytoplankton, the plant form of plankton, and bacteria.
“In addition to looking at the chemical changes in the water, we also looked at the biological recovery,” said Nierzwicki-Bauer, a microbiologist. “We looked at chemical recovery, but also at life. … We really view this as our baseline data. Before we can start looking at what is happening and changing in the lakes, we need to know what was there to begin with. In some lakes, we’re seeing significant changes.”
Sheehan agreed. “We’re not seeing lakes with the acid rain problem they had before,” he said. “The ones that were marginal are now turning the corner and getting fish back.”
Prior to this study, little was known about the effects of acid rain at the bacterial level, in part because the bacteria involved cannot be looked at under a microscope or grown in a lab. “There was really kind of a gap,” Nierzwicki-Bauer said.
Researchers at the Darrin Fresh Water Institute collected a sample of bacteria, broke open the cells and extracted and cloned the DNA. Some of the techniques they used, Nierzwicki-Bauer said, are so new they did not exist just 15 years ago.
Bacteria, Nierzwicki-Bauer said, are resilient. There are thousands of different types of bacteria, which means bacteria can thrive in almost any type of environment. What researchers found, she said, is that some types of bacteria aren’t at all impacted by acid rain. But other types are. The population of a species of bacteria known as Alphaproteobacteria, for example, declines in highly-acidic water. Species of bacteria whose population rises or falls depending on the pH — a measure of acidity — of the water could serve as indicators of lake recovery from acidification. If water chemistry is good, these species of bacteria should be healthy and prevalent.
Acid rain can severely decrease the diversity of plant and animal life in freshwater lakes and ponds; the Clean Air Act, first passed in 1970, aimed to cut the industrial emissions that cause acid rain, a chemical mixture containing nitric and sulfuric acids.
“The Clean Air Act had a positive effect,” Nierzwicki-Bauer said. “Could more be done? Absolutely. We’re not going to declare victory.”
A study like this needs to be long-term, Nierzwicki-Bauer said.
“Even though it’s 13 years, it’s a good beginning,” she said.
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