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Introduced Exotic Species:
Introducing exotics into marine ecosystems in the territory of the Heiltsuk Nation
Introducing exotic species either intentionally or accidentally poses certain threats, some substantial, to both terrestrial and marine ecosystems.
The Heiltsuk Nation is currently monitoring and informing the Central Coast Local Resource Management Planning process. Here we report on the potential risks of introducing exotic species into the traditional marine waters of the Heiltsuk. This report, the first in a series, is a contribution to both the Central Coast discussion, and to reasserting the Heiltsuk's interest in maintaining healthy marine ecosystems.
In an effort to make it more widely useful, we focused on presenting general, ecologic principles, supported by specific examples of what others have learned.
Exotic Introductions: General
The U.S. Congressional Office of Technology Assessment says the U.S. now has a minimum of 4500 "Non Indigenous Species". Of those exotics, approximately 15 percent are considered nuisance species having significant ecological and/or economic impacts.
The Office of Technology Assessment further states that "the significance of non-indigenous species in marine environments (including bays, estuaries, and open coasts) has received relatively little attention compared to terrestrial and freshwater habitats," and that the main "vector" (or cause) of such introductions is humans.
According to conservation biologists who study exotic species, there are some general principles that govern introductions of exotic species into marine ecosystems. Certain of those relate to an ecosystem's susceptibility to invasion.
For instance, scientists have found that:
Those scientists also provided some sobering examples:
- Estuaries are more vulnerable to invasion
than rocky or sandy shores;
- Already heavily-invaded estuaries are still
being invaded, and at high rates;
- Initial invasions lower an estuary's
resistance to subsequent invasion;
- Some invasions take root instantly,
while others require years to decades.
- The Pacific, Atlantic and Gulf coasts have a
total of 400 non-indigenous species (NIS).
- There are 234 NIS in San Francisco Bay,
and 160 in Chesapeake Bay.