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Changes in latitude, changes in attitude - emerging biogeographic patterns of invasion in the Northeast Pacific
Citation:
LEE, II, H., D. REUSSER, W. G. NELSON, AND J. O. LAMBERSON. Changes in latitude, changes in attitude - emerging biogeographic patterns of invasion in the Northeast Pacific. Presented at 17th Annual PICES International meeting, Dalian, CHINA, October 23 - 31, 2008.
Impact/Purpose:
Biogeographic patterns of invasion of near-coastal and estuarine species in the Northeastern Pacific (NEP) are beginning to emerge based on surveys by U.S. EPA’s Environmental Monitoring and Assessment Program (EMAP) and the EPA/USGS synthesis of native and nonindigenous species in the “Pacific Coast Ecosystem Information System” (PCEIS) database.
Description:
Biogeographic patterns of invasion of near-coastal and estuarine species in the Northeastern Pacific (NEP) are beginning to emerge based on surveys by U.S. EPA’s Environmental Monitoring and Assessment Program (EMAP) and the EPA/USGS synthesis of native and nonindigenous species in the “Pacific Coast Ecosystem Information System” (PCEIS) database. One pattern is the large number of nonindigenous species (NIS), with over 70 NIS fishes and 450 NIS invertebrates reported from southern California to Alaska. In terms of latitudinal patterns, the mid-latitude Northern California Ecoregion was more invaded than the Southern California Bight Ecoregion or the ecoregions encompassing Oregon, Washington, and Puget Sound. The high number of invaders in the Northern California Ecoregion is primarily due to the large number of NIS in the San Francisco Estuary. Puget Sound was the second most invaded waterbody with the extent of invasion decreasing below 30 meters. Though less information is available, the three northern ecoregions spanning up into to the Aleutian Islands appear to be substantially less invaded. While the larger estuaries and waterbodies were the most invaded, the smaller “pristine” estuaries without international ports or oyster aquaculture were also moderately invaded by a subset of the invaders found in the larger systems. As a group, estuarine NIS tend to be more widely distributed along the coast than the native species resulting in a trend toward homogenization of the estuaries within the NEP. In comparison, the offshore continental shelf (30-120 m) contained very few NIS and does not show a trend toward homogenization.