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Apex predator - 2 reference results
Apex predator
Apex predators (also alpha predators, superpredators, or top-level predators) are predators that, as adults, are not normally preyed upon in the wild in significant parts of their range. Apex predator species are often at the end of long food chains, where they have a crucial role in maintaining the health of ecosystems.

Definition

The term has been defined in terms of trophic levels. Trophic levels are "hierarchical strata of a food web characterized by organisms which are the same number of steps removed from the primary producers. Primary, secondary, tertiary, and higher level consumers occupy successive trophic levels. One study of marine food webs defined apex predators as greater than trophic level four.

Ecological role

See also Mesopredator release hypothesis.
Apex predators affect prey species' population dynamics. Where two competing species are in an ecologically unstable relationship, apex predators tend to create stability if they prey upon both. Inter-predator relationships are also affected by apex status. Non-native fishes, for example, have been known to devastate formerly dominant predators. One lake manipulation study found that when the non-native smallmouth bass was removed, lake trout, the suppresed native apex predator, diversified its prey selection and increased its trophic level.

Effects on wider ecosystem characteristics, such as plant ecology, have been debated, but there is evidence of a significant impact by apex predators: introduced arctic foxes, for example, have been shown to turn subarctic islands from grassland into tundra through predation on seabirds. Such wide-ranging effects on lower levels of an ecosystem are termed trophic cascades. The removal of top-level predators—often through human agency—can radically cause (or disrupt) trophic cascades.

See also

References

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Last updated on Thursday October 02, 2008 at 13:27:29 PDT (GMT -0700)
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Rapid food web recovery in response to removal of an introduced apex predator.
Mar 01, 2006; Abstract: Non-native species have increased extinction rates, decreased diversity, altered organism distributions, and...
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Paul Viguerie. (formed Viguerie Investments L.L.C. and Apex Predator Fund)(Brief Article)
Sep 01, 1998; Paul F. Viguerie has started his own firm, Viguerie Investments L.L.C and the Apex Predator Fund, which will macro invest in...
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REALLY BIG BIRDIES
Feb 15, 2007; Golden eagles visit Quail Lodge for lunch. The apex predator sits high on the limb of a Monterey pine. Far below, through a low,...
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Decline in condition of northern bluefin tuna (Thunnus thynnus) in the Gulf of Maine.
Jul 01, 2007; Abstract--The northern bluefin tuna (Thunnus thynnus) is a highly mobile apex predator in the Gulf of Maine. Despite current...
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Research from University of Washington provides new data about fisheries research.
Feb 06, 2009; According to recent research from the United States, Many marine apex predator populations have been depleted via targeted...
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