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Cape Breton Highlands National Park of Canada

The Briny Deep - Marine Regions Off Cape Breton Highlands National Park

An underwater view of a kelp bed off Cape Breton Island.
The marine regions surrounding Cape Breton Highlands National Park are an important part of the ecosystem.
© Cape Breton Highlands National Park / G. B. Croft

Cape Breton Island borders on three Parks Canada marine regions. The Magdalen Shallows and Laurentian Channel marine regions are found within the Gulf of St. Lawrence while the Scotian Shelf marine region is part of the Atlantic Ocean. The Gulf of St. Lawrence and Atlantic Ocean are effectively separated by the island. Along the coast, the Cape Breton Highlands National Park boundary follows the average high tide line.


The tail end of a humpback whale as it dives in the Atlantic Ocean.
Tidal upwelling along the Laurentian Channel supports a rich marine food chain including invertebrates, fish and marine mammals such as this humpback whale.
© Terra Nova National Park / M. Rosen

The Atlantic Ocean and the Gulf of St. Lawrence are an important part of the northern Cape Breton ecosystem. On both coasts, tidal up-welling along branches of the Laurentian Channel, a deep canyon in the sea floor, brings oxygen- and nutrient-rich water to the surface which supports a complex marine food chain including algae, plankton, invertebrates (such as crab, lobster and squid), fish (such as cod, haddock, herring, swordfish and tuna) and whales.


A map of the Atlantic Provinces, showing the location of the Laurentian Channel between the mainland and Newfoundland.
A map of the Atlantic Provinces, showing the location of the Laurentian Channel between the mainland and Newfoundland.
© Cape Breton Highlands National Park / Parks Canada

 
Sea ice glints coldly in winter along the Gulf shore of Cape Breton.
The Gulf of St. Lawrence is more likely to freeze over during the winter than the Atlantic Ocean because it is more shallow and less salty. Nevertheless, it is rich in marine species.
© Cape Breton Highlands National Park / Parks Canada

The Gulf is shallower and less salty than the Atlantic Ocean, which makes it slightly warmer in summer but also more likely to freeze in winter. With water warmer than any coastal waters north of Cape Cod, the Gulf is both highly productive and rich in species.

The number and variety of intertidal species such as periwinkles and barnacles is small along both coasts of the park. This is mainly due to ice scouring, storm waves, cold water temperatures and little difference in water level between low and high tides.