Sea otters (Enhydra lutris) are marine mammals capable of spending their entire lives in water. Being carnivorous in nature, they feed on sea urchins, crabs, fishes, mussels and clams. They are referred to as keystone species due to their profound impact on marine ecology. The interaction between sea otters, sea urchins and kelp forests has been studied as a model of the impact of predator-prey interaction on community ecology. Sea otters are keystone predators, whose presence has a far-reaching influence on the marine food web by affecting the population of sea urchins in particular, and kelp forests & other marine organisms in general. There has been a steep decline in sea otter ...view middle of the document...
in Soulé et al 1240). Therefore, to maintain the diversity and richness of the coastal marine ecology, kelp forests should be preserved.
Impact of sea otters on community ecology
The presence or absence of sea otters influences marine ecology at the community-level. Studies have shown that kelp forests enhance the underwater environment, providing a suitable habitat for fishes. The declining kelp beds in California in the mid 1900’s propelled the Kelp Habitat Improvement Project, whereby attempts were made to eliminate sea urchins that are primary predators of kelps. Studies showed that the elimination of sea otters during the 1800s from the Californian waters might be responsible for the dwindling numbers of kelp forests. Further studies have also shown that the population density of sea otters affects seaweed biodiversity as well. In a study conducted in Alaska on three different bays, the Torch Bay, Deer Harbor and the Surge Bay, it was found that the presence of sea otters led to a decrease in the population of sea urchins, which led to an increase in the population of seaweeds. In addition, it was also found that annual kelps predominated the areas where sea otters were present, and perennial kelps predominated in areas that had lesser sea otter populations (qtd. in “Interaction with kelps & sea otters”).
As is evident, sea otters are vital for maintenance of the kelp communities that are primary habitats of other coastal marine organisms, including fishes. Their absence would lead to a significant reduction in the marine biodiversity.
Inclusion of sea otters in the Endangered List
In view of the influence of sea otters on coastal marine ecology and underwater communities, their value in the maintenance of coastal biodiversity cannot be undermined. Unfortunately, their populations have shown a steep decline over the years. The sea otter was widespread throughout Western Europe, but its numbers declined dramatically during the 20th century (Chanin 6). The sea otters completely disappeared or were reduced to a rare minority in most parts of the world. They are now an endangered species owing to widespread diseases, pollution of water through sewage and chemical contamination, oil spills and pesticides, apart from being shot by hunters for their soft, thick and waterproof fur. Mortality from natural predators is another cause of concern (“Impacts of Biodiversity”). The continuing decline in sea otter populations have therefore led to population explosion of sea urchins, which are its primary prey. Their overpopulation is, in turn, affecting the kelp communities on which they feed voraciously. Overpopulation of any one organism in the community affects the population of its prey, resulting in habitat degradation, imbalance of ecosystem and biodiversity (“Community Ecology”). Therefore, the protection of sea otters is an international concern.
Sea otters are a keystone species and protecting them indirectly leads to the...