Muskoka’s lakes face new environmental threat: report

[Spiel]

Muskoka’s lakes face new environmental threat: report

 

 

December 10, 2008

Karen Longwell / bracebridgeexaminer.com

 

 

An emerging threat to Muskoka’s lakes and forests is part of a new report published in the international journal Science.

 

The effect of declining levels of calcium on aquatic creatures in soft water boreal lakes was reported for the first time in the Science article this November.

 

“This is not a small issue,” said Norman Yan, a York University professor and limnologist (lake scientist) who lives in Bracebridge. Yan was one of the authors of the report.

 

According to the study, long-term consequences of calcium decline could result in areas where forests won’t grow back well. Lakes could also start to lose calcium-rich organisms.

 

A type of water flea, Daphnia, was the aquatic creature studied in the report, said Yan. The water flea is a crustacean, like little tiny shrimp, not an insect, he said.

 

While all animals, including humans, need calcium, the water flea is a calcium-rich creature. Despite its small size, about two millimetres long, the water flea is an important part of our ecosystem and is responsible for eating the algae in our lakes, he reported.

 

“The entire volume of Lake Muskoka is passed through the stomachs of these water fleas twice a month,” said Yan. “So these guys are really working hard on our behalf to keep the water clean.”

 

Typically there are 50 Daphnia in every litre of lake water, he said.

 

Yan has been studying lakes in Haliburton and Muskoka for about 38 years. He noticed calcium levels starting to fall and along with the other authors of the report, wanted to study the life forms affected by the decline.

 

They chose the water flea because it is easy to get a large sample of them and they need lots of calcium.

 

The study found that water fleas do poorly when calcium levels are low in a lake.

 

“It turns out if calcium is below one and a half milligrams per litre, these animals do very badly,” said Yan.

 

About 40 per cent of Muskoka’s lakes have less than one and a half milligrams of calcium per litre, he said.

 

“We are kind of likening these water fleas to canaries in the coal mine,” Yan explained. “So if one calcium-rich animal is in trouble, then we darn well better find out about all the other calcium-rich animals, like crayfish and snails.”

 

Calcium in the lakes comes from minerals in the soil, but the soil in many parts of Muskoka is thin. Unlike other types of rocks, the rock under the soil, granite, does not have many nutrients, said Yan.

 

In the industrial age, minerals in the soil were leached through acid rain and logging.

 

“What takes the minerals away is six decades of acid rain and then logging, followed by forest regrowth,” said Yan.

 

In many areas of Muskoka where the soil is thin, forests can regrow about three times, but then there aren’t enough nutrients to regrow the trees, he said.

 

The study included about 40 lakes across Muskoka and Haliburton and also lakes in Nova Scotia and the Adirondacks.

 

The study finds acid rain is still playing a role in our ecosystem.

 

“Tragically the acid rain story is not yet over . . . but it is much better than it was,” said Yan.

 

The rain is 50 per cent less acidic than it was 25 years ago due to reduced sulphur emissions, he said. But it is still too acidic for about 25 per cent of the land, and a lot more acidic than 100 years ago, he said.

 

“We have to keep working to reduce sulphur emissions,” said Yan. Yan hopes other scientists will help in the study of calcium decline, and that Canada and the United States will take further action on sulphur emissions regulations.

 

“What we hope we have done is open the door on a new, or at least not well understood environmental threat that we can quickly learn more about,” said Yan.

 

Yan will continue to work on calcium decline in a different study with two professors from Trent University and another from York University.

 

This study aims to find the effect of logging and forest fires on calcium levels. It will also try to find out how many of Muskoka’s 1,600 lakes have a problem with calcium.

 

The District of Muskoka, Ministry of the Environment and the above universities are collaborating on this project.