Marine Ecosystems
Submarine canyon
DISTRIBUTION
Worldwide around continental shelf edges
PHYSICAL OCEAN CHARACTERISTICS
Steep, branched valley walls extending to the deep sea; nutrient-rich waters
KEYSTONE SPECIES
Cold-water corals, sponges, sharks, groundfish, marine mammals
ECOSYSTEM SERVICES
Fisheries, carbon storage, nutrient upwelling, biodiversity hotspots
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Submarine canyons are deep and intricate underwater valleys. Millions of years ago, canyons were eroded into the ocean floor along continental shelves by geological processes, like movement of tectonic plates or erosion by ancient currents. Submarine canyons are often V-shaped cuts along a continental shelf, with steep rock walls that narrow down as they reach the seafloor. Each canyon is unique in its shape and size, influenced by oceanographic conditions like ocean currents, temperatures and water salinity. Submarine canyons can be massive and may even have smaller canyons or channels branching from them, creating intricate structures.
Submarine canyons are essential parts of the deep-sea environment, playing a crucial role in nutrient cycling and carbon storage. Particles of organic matter, made up of dead plants and animals, and sediments fall to the seafloor from the ocean surface. This sinking organic matter contains carbon, and as it falls and accumulates on the seafloor, it is stored there for millions of years, causing submarine canyons to act as carbon sinks. Moreover, strong currents carry nutrients from deeper ocean waters into submarine canyons in part thanks to their shape and structure. The unique structure and flow dynamics of these canyons help induce “upwelling events” that push nutrient-rich waters to the surface as they are carried in from the deep-sea.
This combination of strong currents and upwelling events can cause submarine canyons to become hotspots for marine life, creating rich feeding grounds and habitat for many marine animals. In fact, these features and phenomena can create the perfect conditions for cold-water corals and sponges to thrive, allowing them to grow into large reefs, gardens and forests. Cold-water coral reefs and sponge gardens provide food, shelter, spawning grounds and nurseries for many other species, including fish, crabs, marine worms, brittle stars and sea stars. The nutrient-rich waters and shelter provided by canyons attracts many other species, like sharks and whales, to these biodiverse regions.
Submarine canyons are important and unique ecosystems, but the long-lived, habitat-forming organisms, like corals and sponges, that they support are incredibly vulnerable to threats from human activities. Deep-sea fishing is a primary threat to submarine canyon environments, as bottom-contact fishing gear can easily break and kill corals and sponges, which may take decades or centuries to recover. Offshore oil and gas activities and deep-sea mining can also disturb sediments, release oil and other pollutants into the water, and put all marine life in submarine canyons at risk. This is why it is so important to protect vulnerable habitats, like submarine canyons, and marine life that depend on these ecosystems from destructive practices that can threaten their existence.
Fun Facts
- Canada has many submarine canyons along it’s coasts, with at least 13 canyons found in Atlantic waters and nine in Pacific waters.
- Submarine canyons are home to a number of deep-sea species like thorny skates, redfish, and endangered species like the northern bottlenose whale.
- Bamboo and bubblegum corals are some of the most common cold-water species, especially in submarine canyons of the northwest Atlantic Ocean.
- Humpback whales have been found to feed on plankton at the sea surface above canyons, while sperm whales hunt for squid in the depths in both Pacific and Atlantic submarine canyons.
FURTHER READING
Blue Habitats – Submarine Canyons
Fisheries and Oceans Canada – Closures to Protect Sensitive Benthic Areas
Fisheries and Oceans Canada – The Gully Marine Protected Area