Acid Rivers to Oceans

It’s your quintessential good-news/bad-news story. The good news? Emission-control legislation enacted in Canada and the U.S. over the last three decades has resulted in significant acid rain declines in this country. The bad? Despite those efforts, much of Atlantic Canada still gets more acid precipitation than local ecosystems can bear, according to Environment Canada. And a recent study published in the scientific journal Proceedings of the National Academy of Sciences claims the impact of acid rain is greatly amplified in shallower coastal waters.

Ocean acidification results from the mixing of seawater and chemical compounds, such as carbon dioxide, sulphur and nitrogen, which lowers the water’s pH level. Those same chemicals, released by burning fossil fuels, cause acid rain. In the ocean, those compounds are preventing some marine organisms, such as sea urchins, corals and certain planktons, from making hard outer shells. And as an essential food or habitat source for many other species, the loss of these marine organisms could affect entire ocean ecosystems.

“That effect is most pronounced near the coasts, which are already some of the most heavily affected and vulnerable parts of the ocean due to pollution, over-fishing and climate change,” notes Scott Doney, the study’s lead author and a senior scientist in the Department of Marine Chemistry and Geochemistry at the Woods Hole Oceanography Institution.

This is, no doubt, hardly surprising news to Atlantic Canadians. Thanks to prevailing winds that carry pollution from industrial centres in the eastern U.S., southern Ontario and Quebec, the country’s easternmost provinces have long been concerned with acid precipitation—and its affects on local aquatic life.

Case in point: Atlantic salmon. Inner Bay of Fundy Atlantics have been listed as endangered by the Committee on Endangered Species in Canada (COSEWIC) since 2001, and late in 2009, all Canadian populations of Atlantic salmon were listed by COSEWIC as a “high priority candidate.” The culprit? You guessed it. Acid rain is considered the main cause of Canada’s once-mighty salmon population’s demise.

The good-news/bad-news story doesn’t end there, though. Under the national Acid Rain Strategy for Post-2000, Nova Scotia, New Brunswick, Ontario and Quebec have committed to additional sulphur dioxide reductions of 30 to 50 per cent. That’s the good news. The bad? According to the conclusions of the 2004 Canadian Acid Deposition Science Assessment Document, further sulphur dioxide reductions in both Canada and the U.S. are necessary to protect Eastern Canadian ecosystems from acid rain. For Atlantic salmon and other aquatic species, however, time may be running out. It’s up to us to help!