Marine Ecosystems
Fjords
DISTRIBUTION
Cold temperatures to polar latitudes of the north Atlantic, north Pacific and south Pacific
PHYSICAL OCEAN CHARACTERISTICS
Long, deep, narrow inlets surrounded by steep cliffs, often with strong tides
KEYSTONE SPECIES
Cold-water corals, sea anemones, orcas, seals, salmon and char
ECOSYSTEM SERVICES
Fisheries, ecotourism, aquaculture, artisanal fishing and hunting
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Fjords are long, narrow, deep bodies of water along the coasts of areas formerly covered in glaciers. As the glaciers began to retreat thousands of years ago, they flowed down towards the sea, eroding deep, sharp canyons in the bedrock. As the glaciers continued to melt, these canyons were flooded by rising sea levels, creating fjords. These marine ecosystems are typically surrounded by tall mountains with steep sides that continue below the waterline.
As a result of their steep sides, fjords can reach extreme depths only a few metres from shore. On average, fjords can reach 200 metres in depth, however the deepest fjords on Canada’s west coast are almost 500 metres deep. The long, narrow nature of fjords means that they may extend far inland from the coast; the longest fjords extend hundreds of kilometres inland. The water in fjords come from two sources: saltwater from the ocean, and cold, freshwater from upstream rivers, glacial meltwater and rainfall.
Most fjords are found in the northern hemisphere, which was the half of the planet most significantly covered by glaciers during past ice ages. They are commonly found in northern Europe, Greenland and Canada but there are also fjords in some areas south of the equator that are near coastal mountain ranges, for example in New Zealand and Chile.
These unique systems allow deep-sea organisms to live close to shore, even somewhat inland, a fact that is abnormal or impossible along typical coasts. Deep-water coral reefs are also found in fjords. Most people think of coral reefs as tropical but cold-water corals live on seamounts, underwater mountains, and in deep fjords, in cold temperate or sub-polar waters. Reefs in both northern and southern hemisphere fjords are characterized by extremely old, slow growing corals, like bubblegum coral and anemones that provide important habitat for fishes and invertebrates, like crabs.
Other animals that live in fjords include whales, such as orcas, Greenland sharks, several species of seals, different salmon species and Arctic char. These species are the top predators in fjord food webs, which also include numerous species of forage fishes and other prey.
Because of their dynamic shape, there can be limited water exchange between fjords and the ocean, resulting in pollution acting as the primary threat to fjord ecosystems. Invasive species pose a problem to these systems as well. Like in any marine ecosystem, destructive fishing practices can also threaten fjord habitat and risk fisheries for species that live in fjords.
FUN FACTS
- Fjords get their name from the Old Norse fj?rðr, which was used to describe a narrow inlet of the sea.
- Fjords were created by a combination of glacial erosion, meltwater and flooding of sea water.
- Fjords are often set in a U-shaped valley, with a relatively wide and flat basin floor and steep, almost vertical walls.
- These systems are important transition habitats between the land and sea and provide habitat for a variety of species.
EXPLORE FJORDS
Check out some of the fjord ecosystems in Canada we visited on our expeditions to the Central Coast of British Columbia and Imappivut off the coast of northern Labrador!
