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Canada's Ocean Basins

By CarolAnne Black

publishedSeptember 1, 2022
Image of the Heiltsuk Nation. A forested coastline littered with inlets on a beautiful sunny day, with mountains in the background.

Coast to Coast to Coast: How well do you know Canada’s three ocean basins?

Canada’s coast, the longest of any nation in the world, touches three ocean basins. These basins are interconnected parts of our one global ocean, each with its special character. The Pacific, with its nutrient-rich waters and hydrothermal vents, supports an unrivaled abundance of marine species. The Atlantic takes up vast amounts of carbon dioxide and supports most of Canada’s fisheries value. The Arctic, small and mighty, into which 1/10th of all the world’s river water drains and home to unique life forms and cultures, is also the basin most at risk from climate change.

“Canada is blessed with a quarter-million kilometres of stunning coastline, historically harbouring some of the largest numbers of marine mammals, fish and seabirds in the world. We can all help to protect and restore these riches, and make sure our ocean stays healthy and safe for generations to come”, says Ocean School Co-Founder Boris Worm. “Let Ocean School take you on a learning journey to explore places, people, and stories from our three coasts.”

The Pacific Ocean
Just west of North America, the Juan de Fuca tectonic plate is being driven beneath the continent. In this process, called subduction, the plates are bending and cracking. It is a multimillion-year re-shaping of the Earth’s surface, and causes earthquakes and tsunami waves that sometimes travel toward the North American coast, and also halfway around the world.

Closer to shore, ocean currents along the western coast of North America bring nutrients from the seabed to the surface and shallow coastal waters. These nutrients fuel the growth of algae and form the base of the marine food web. The abundance of algae provides food and habitat for many kinds of marine life. Juvenile salmon swim down-river from where they hatched, and mature into fish that can live in saltwater in the safety of dense kelp forests, where great strands of wavy green reach from their roots in the seabed toward light at the surface.

The Haíɫzaqv (Heiltsuk) people know these coastal waters intimately. They have been harvesting fish such as salmon in what is now known as British Columbia’s Central Coast for over 14 millennia. For the Haíɫzaqv, when the salmon return from the ocean to the rivers to spawn, they are also coming to nourish the people. In their relationship with the ocean and these important fish, the Haíɫzaqv see a human responsibility to care for the salmon, including ensuring they come home to a healthy environment.

The Atlantic Ocean
Reaching from shore up to 200 km and more, extensive continental shelves run along much of the east coast of Canada. These are parts of the continent under the sea, and because they are relatively shallow, at an average depth of 90 m, they can be sunlit and provide ideal habitats for many marine species.

This vast nearshore region includes the Bay of Fundy, where due to its unique shape, the tides reach 16 m, the highest in the world. Strong tidal currents bring nutrients into the Bay that support the ocean food chain: seabirds come to forage in the muddy tidal flats, and endangered right whales spend their summers feeding on tiny crustaceans called copepods.

Crab and lobster, bottom-dwelling crustaceans, thrive in the Bay and the coastal and continental shelf area of the Atlantic: these regions are just the right temperature, provide ample hiding spots like crevices in rocks. They are also home to plenty of fish, molluscs and other small marine life to eat. Because of this rich ecological diversity, the Atlantic Ocean supports the most productive fisheries in Canada.

Further north, vast amounts of the carbon dioxide emitted into the atmosphere are taken up by the ocean. In the cold of the North Atlantic, carbon dioxide is drawn down into deep ocean currents that travel the globe. Some of these currents resurface after more than 1,000 years on the other side of the world. This ‘breathing’ down of carbon dioxide into the deep sea makes the Atlantic Ocean critical to moderating the effects of climate change.

The Arctic Ocean
The Arctic Ocean basin holds just 1% of the world’s ocean water, and covers only 3% of the ocean’s area. Yet 10% of global river water flows into the Arctic Ocean, and it is where 20 of the world’s longest rivers end their journeys. All of this freshwater (non-salty water) flowing into the Arctic Ocean forms a 200 m thick layer of cold water at the surface that creates the special conditions needed for sea ice. This layer of cold water insulates the ice from warm saltwater that originates in the Atlantic and Pacific. Through this unique interaction, river run-off stops the ocean from continuously melting the polar ice. Sea ice in the Arctic is critical to the Earth’s climate and to unique Arctic species and cultures like the Inuit.

One third of the world’s coastline and one quarter of its continental shelf are in the Arctic. The continental shelf region is one of abundant marine life, and the Arctic is home to about 240 fish species. One of the most abundant, Arctic cod, are an important link in the Arctic food web: they prey on bottom-dwelling animals and plankton; seabirds, seals and whales prey on them. In their younger life stages, Arctic cod rely on sea ice as a protective habitat. The continued loss of sea ice due to climate change may impact these fish and the entire Arctic ecosystem.

Many of us in Canada live far from the ocean. If we live by the coast, we may know our local coast better than we know others. On our journey to learn about the ocean, increasing our ocean knowledge includes discovering places that are far from us. Ocean knowledge empowers us to understand our ocean as one interconnected system, connected to all of us on land, with ecosystems and basins that hold unique value and character worth protecting.

About CarolAnne Black

CarolAnne Black tells ocean stories. She writes on all topics related to the ocean, and especially loves to work on writing projects that help empower girls and women in ocean science. In her work, CarolAnne gets to talk with ocean experts from around the world and write about how they’re working to understand and protect our global ocean. She likes to swim with her three kids in the Ottawa River by their home and talk about how the water is making its way back to the ocean.

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