Brooktrout lake was once teeming with the speckled fish after which it is named, but by the 1980s, it had become one of hundreds of lakes and ponds in the Adirondacks of upstate New York that were devoid of fish. The culprit: acid rain from the burning of fossil fuels.

1990s to 2000s

As the lake slowly stabilized, phytoplankton and zooplankton species recovered.

2005

When the waters had improved enough, scientists reintroduced fish to the lake.

2010

Within five years, the brook trout were able to successfully reproduce.

The bodies of water in this region are among the most impacted by acid deposition in the United States.

But reductions in sulfur dioxide emissions over the past three decades, fostered by federal environmental regulations, have allowed the pH of the Adirondack lakes to stabilize over time — giving scientists a unique opportunity to attempt to reintroduce fish to the lake.

Two researchers from the Academy of Natural Sciences of Drexel University — Donald Charles and Frank Acker — were part of a nine-institution group that has spent two decades documenting changes in the lake and their effects on species such as bacteria and fish.

Their research, which was published in 2015 in the journal Environmental Science and Technology, marks the most comprehensive long-term study of how acidification affects lake ecosystems to date.

The researchers documented the water quality and aquatic plant and animal life recovery throughout the 1990s and 2000s. They discovered that, as lakes recover, more species of phytoplankton and zooplankton were found, thus beginning to rebuild the food chain.

By 2005, the waters had improved enough that scientists decided to re-introduce fish to the lake.
In the paper, the researchers describe the complex process by which they reconstructed historical conditions, re-introduced tagged fish to the lake and then meticulously monitored changes in the lake’s species and water chemistry over time.

Finally, in 2010, the researchers discovered that the brook trout could not only survive but also reproduce.

This achievement was the first demonstration of food chain recovery through re-introduction and re-establishment of fish in a region that had been heavily affected by acid deposition.

Most significantly, the study underscores the success of national and international environmental regulations that limit pollutants, enabling nature to begin its healing process.

“Although it took a long time, the recovery of fish in Brooktrout Lake shows that the reduction in emissions did pay off,” says Charles.