Seamounts | Oceana Canada

Marine Ecosystems

Seamounts

Distribution

Worldwide at the edges of tectonic plates

Physical Ocean Characteristics

Deep, low energy, nutrient-rich waters

Keystone Species

Coldwater corals, sponges, rockfishes

Ecosystem Services

Fisheries, mineral extraction, ecotourism, biodiversity hotspots

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Seamounts are unique geological features commonly referred to as underwater mountains that rise a thousand metres from the base of the seafloor or more. Seamounts are typically created by extinct or inactive volcanoes that had their lava piles rise abruptly and form a peak.  While many seamounts are located in the deep ocean, some peaks are found only a few dozen metres below the sea surface, meaning they connect the deep ocean to shallow ocean habitats. Because seamounts can span from deep, cold, dark waters to shallow, warmer waters, they provide incredibly important habitat for corals, sponges, octopuses, and fish, as well as feeding grounds for larger marine animals like whales, sharks, and even seabirds. Seamounts are internationally recognized as biological hotspots and critically important ecosystems to protect for the health of our oceans.

Seamounts can be found in every ocean basin in the world. Since they are the product of once-active volcanoes, they are commonly found near the edges of Earth’s tectonic plates or at mid-plate hotspots, which are isolated areas where plumes of lava rise up and erupt through the Earth’s crust onto the seafloor. When tectonic plates meet and collide, it forces the ocean crust down into the Earth where it is melted by the hot temperatures and high pressures. This process forms magma that rises back up to the ocean floor, creating volcanoes and seamounts.

The steep slopes of seamounts shape ocean current patterns and carry nutrients from deeper waters up their sloping sides to the sea surface, a process known as upwelling. This process provides a constant food supply for all kinds of marine creatures, from corals to invertebrates to fishes to whales. The hard surface of these seamounts provides an ideal foundation for corals, sponges, and anemones. As these animals grow and reproduce, they create complex three-dimensional living habitat for other species like crustaceans and sea stars, as well as important nursery and foraging habitat for fish, octopuses and many other species of marine wildlife. Seamounts offer this oasis amidst otherwise muddy, relatively barren expanses of seafloor, and because of this some seamounts have their own endemic species (species that can be found nowhere else). With less than one per cent of known seamounts having been explored, we still have a lot to learn about them and the sea creatures that call them home.

The isolation and uniqueness of seamounts’ ecosystems make them especially sensitive to human disturbances. Harmful activities such as bottom-contact fishing, especially bottom trawling, mining, oil and gas explorations, and climate change threaten the marine wildlife that inhabits seamounts. 

 
 

FUN FACTS

 

  • Seamounts are underwater mountains that were formed by volcanic activity and rise at least 1,000 metres from the bottom of the seafloor.
  • The tallest mountain on Earth is actually a seamount; Hawaii's Mauna Kea, a dormant volcano, rises more than 9,100 metres from its base on the seafloor (Mount Everest is 8,848 metres tall).
  • New estimates suggest that all together, seamounts encompass about 28.8 million square kilometres of the Earth's surface. That is more than deserts, tundra, savannah or any other single land-based habitat.
  • Many seamounts support species that are found nowhere else in the oceans.
  • It is estimated that there are over 30,000 seamounts in the Pacific Ocean alone.
  • The only known seamounts in Canada are found in the Pacific Ocean off the coast of British Columbia.

 

EXPLORE

 

Dive in and learn more about the Northeast Pacific Seamounts that we explored off the coast of British Columbia. We are calling on the government to implement permanent protection measures for these important seamounts. You can add your voice to protect this incredible underwater mountain range here!

 

 

FURTHER READING

 

NOAA National Ocean Service

NOAA Ocean Exploration and Research

Smithsonian Ocean

Woods Hole Oceanographic Institution

World Wildlife Fund

the Full Creature Index