WHAT IS
OEAN ACIDIFICATION?

Ocean acidification (OA) is the process where carbon dioxide is absorbed by the oceans, causing a chemical reaction that leads to a reduction in seawater pH. The oceans absorb about one third of these carbon dioxide emissions every year. Since the industrial revolution, the burning of fossil fuels has led to an exponential increase of carbon dioxide in the atmosphere, resulting in an approximately 30% increase in ocean acidity. As carbon dioxide levels in the atmosphere continue to rise, so will the ocean’s acidity.

 

One of the major consequences of ocean acidification is decreases in the amount of shell-building materials available to shelled organisms, such as oysters, mussels, and corals. Ocean acidification is also harmful to the development and bodily functions of many organisms, such as crabs, lobsters, and fish, and can even impact normal animal behaviour.

 

Many of the species most vulnerable to ocean acidification are critical habitat formers and sources of food for their ecosystems, such as oysters, mussels, and many types of plankton. A lot of the species most impacted by ocean acidification are also important economic and food resources for humans, including important shellfish such as oysters, mussels, crabs, and lobsters.

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How is Canada impacted by OA?

 

Canada has the longest coastline of any country in the world and is surrounded by three ocean basins all with unique dynamic processes. Situated at high latitudes, the waters surrounding Canada are also naturally more vulnerable to OA, as carbonates are more soluble in cold water.

 

Each coastal region in Canada faces its own set of challenges when it comes to OA. 

 

• In the Pacific, seasonal upwelling brings naturally acidic waters close to the ocean’s surface, negatively impacting important shellfish like oysters.

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• The cold waters of the Arctic are especially vulnerable to OA due to increased absorption of atmospheric carbon dioxide and freshwater input that both increase seawater acidity and decreasing ice cover that further accelerates these processes.

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• Ocean acidification in Atlantic Canada is influenced by both the input of acidic Arctic waters from the Labrador Sea, as well as the St. Lawrence, and threatens many socioeconomically important shellfish such as lobsters and scallops. ​​