Why Sea Otters Are So Important to Their Ocean Habitat: The Role of Sea Otters in Ecosystem Balance

raft of sea otters, group of sea otters

Sea otters — with their playful demeanor and iconic appearance — are more than just adorable creatures. They play a crucial role in maintaining the balance of their ocean habitat, making them indispensable to the ecosystem. This article explores the sea otter habitat, the importance of sea otters, and the role of sea otters in the ecosystem.

The Sea Otter Habitat

The sea otter (Enhydra lutris) is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean and has a habitat that is primarily in the shallow coastal waters. They are known to inhabit areas that have kelp forests, which provide them with ample food supply and protection from predators. The kelp forests also serve as a place for sea otters to anchor themselves during rest periods by wrapping themselves in the kelp to prevent drifting.

In North America, there are two distinct sea otter subspecies. The northern sea otter (Enhydra lutris kenyoni) is found in the Aleutian Islands, Southcentral and Southeast Alaska, British Columbia, and Washington. This subspecies is known to inhabit a range of environments, including areas that are rocky, areas with soft sediment, and areas with extensive vegetation. 

northern sea otter The southern sea otter (Enhydra lutris nereis) — also known as the California sea otter — lives in waters along the California coastline. This subspecies is found in nearshore environments, including bays, estuaries, and coastal waters. They are often found in areas with kelp forests, but can also be found in areas with seagrass beds.

Both subspecies of sea otters are known to spend the majority of their time in the water, but they will also come ashore to rest, groom, and nurse their young. They are known to be more terrestrial in areas where there are fewer human disturbances.

The Importance of Sea Otters in Their Ecosystem

Sea otters are a keystone species, meaning their role in their environment has a greater effect than other species. As top predators, sea otters are critical to maintaining the balance of nearshore ecosystems, such as kelp forests, embayments, and estuaries. 

Sea otters’ high metabolism and lack of blubber require them to consume between 25% and 30% of their body weight each day. This also helps them to control the numbers of their prey species, such as crabs, clams, urchins, snails, and worms. This appetite for invertebrate species exerts a strong influence on prey size and number and how they live and move in their habitat. Without sea otters, sea urchins can overpopulate the sea floor and devour the kelp forests that provide cover and food for many other marine animals. Once urchins have decimated all of the kelp in an area, they carpet the ocean floor, creating what is known as an urchin barren.

By maintaining healthy kelp forests, sea otters also indirectly help to reduce levels of atmospheric carbon dioxide — a prevalent greenhouse gas — as kelp absorbs and sequesters carbon. This makes the sea otter’s ecological role vital for the health of the planet, even helping to combat climate change.healthy kelp forest

The presence of sea otters also supports diverse and healthy seagrasses, another important nearshore community that helps battle climate change. The vast, underwater meadows and deep root systems of seagrass beds represent less than 0.2% of the seafloor, but they provide up to 10% of the ocean’s carbon storage.

In the 1970s, a scientist named Dr. James Estes recognized that he could study the influence of sea otters on other species in their environment by comparing the coastal habitats in Alaska’s Aleutian Islands where sea otter populations had recovered to similar places where sea otters were absent. Dr. Estes found that the presence of sea otters had a dramatic effect on coastal habitats.

Similar to the information mentioned earlier in the article, Dr. Estes found that in places where sea otters were present, they controlled the size and number of sea urchins, allowing kelp forests to thrive. This type of relationship between a predator (sea otter), herbivore (urchin), and plant (kelp) is known as a trophic cascade. The complexity of trophic cascades can vary extensively from place to place, but this basic pattern is the foundation for understanding how sea otters fit into a healthy coastal environment.

Sea Otter Habitat Loss

Despite their importance, sea otters face numerous threats, including sea otter habitat loss. Human activities — such as pollution, climate change, and overexploitation of wildlife — have pushed countless species to the brink. Sea otters are no exception. Direct conflict with humans, through shootings, fishing gear entanglements, and boat strikes, take a toll on sea otters, but oil spills, pollution, disease, and loss of kelp pose major threats.

sea otters float in kelpThe importance of sea otters cannot be overstated. They play a crucial role in maintaining the balance of their ocean habitats, making them indispensable to the ecosystem. By protecting sea otters and their habitats, we can help preserve biodiversity and combat climate change.

At Sea Otter Foundation & Trust, we work to ensure the survival and recovery of sea otters in their habitats by building funds to support research, conservation, and education. You can learn more about the all-important efforts of our grant recipients by watching our interviews with them. These efforts are funded directly by our supporters, so consider advancing our crucial work by adopting an otter or making a donation today!