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Tadpole Shrimp cont. Impacts to Vernal Pool Habitat The main threat to the continued existence of the vernal pool tadpole shrimp, as well as almost all other vernal pool species, is continuing loss of habitat, especially due to residential/commercial development and lands converted to agricultural uses. Vernal pool habitat is rapidly diminishing throughout California. This conversion or use of lands containing the remaining vernal pools is expected to continue because of the desirability of and economic feasibility of building on essentially flat lands (slopes of no more than 3-4 %) which are often close to metropolitan areas. Present estimates for the loss of vernal pool habitat in California’s Central Valley range from 65-90% of its former extent. In Southern California, San Diego County has documented the loss of 90-95% of its historic vernal pool habitat. Vernal pools and vernal pool complexes also are subject to threats in the form of: interrupted watersheds for pools and complexes, invasions of aggressive non-native plant species, gravel mining, fertilizer and pesticide contamination, overgrazing by livestock, off-road vehicle use, and contaminated stormwater runoff. Species Range and Status as Federally Endangered The vernal pool tadpole shrimp is a species found only in California. The shrimp ranges in the Central Valley from around Visalia (Tulare County) in the south to the Redding area (Shasta County) in the north. The easternmost known location is around 3,000 feet in elevation in the central Sierra Nevada foothills (Merced County). The westernmost known location is on the Warms Springs Seasonal Wetlands of the Don Edwards San Francisco Bay National Wildlife Refuge in Alameda County. This property, which contains some of the very few vernal pools in the South San Francisco Bay Area, was acquired by the U.S. Fish and Wildlife Service in 1992. The vernal pool tadpole shrimp also was recently discovered on the privately owned Pacific Commons Project site in Fremont which is adjacent to the Don Edwards San Francisco Bay National Wildlife Refuge. These two locations are unique since they comprise the only |
Last updated:
May 27, 2008
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