Wednesday, September 23, 2009

Salmon as a Keystone Species


Salmon are a keystone species meaning that in many ways their abundance and distribution drives the community dynamics of their ecosystems. From fly larvae to bears, literally hundreds of species feed on salmon and their carcasses when they return. These marine derived nutrient subsidies dramatically increase both aquatic and terrestrial productivity when salmon return in high abundance. As salmon stocks have dwindled around the region the indirect impacts on their ecosystems are too often undocumented and unconsidered. Apex predator species such as grizzly bears are especially vulnerable because of their food demands. Other stream rearing salmonids such as coho, chinook, steelhead, bull trout and cutthroat may also be adversely affected by lower biomass of salmon entering freshwater. See a couple of interesting articles.

A recent study in Washington and Oregon found that 138 species feed on salmon.

http://www.theglobeandmail.com/news/national/a-keystone-species/article1293902/

Bears are at risk because of declining salmon abundance

http://www.theglobeandmail.com/news/national/british-columbia/an-ecosystem-in-turmoil-puts-its-predators-at-risk/article1293897/

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