Strategies for Ecological Restoration of the Middle Rio Grande in New Mexico and Recovery of the Endangered Rio Grande Silvery Minnow

摘要

Issues relevant to management of arid land aquatic ecosystems include: (1) a poor understanding of the extent and linkages of an aquatic ecosystem, (2) human population growth coupled with a highly variable water supply, (3) hydrologic modifications of rivers associated with dams, levees, canalizations, and diversions, (4) impairment of water quality, (5) alteration of vegetative communities of catchments and riparian zones, (6) introduction of invasive non-native species, and (7) imperiled native species. All of these issues occur in the Middle Rio Grande of New Mexico and the first six in combination have been responsible for the impediment of its native aquatic biota. The extinction of two fish species, extirpation of 13 others, and endangermentof the Rio Grande silvery minnow, a pelagic-spawning species with an enormous potential for recolonization of habitats, has been caused by a century of river and landscape modifications. Erosion from heavily grazed grasslands coupled with appropriation of surface flows for irrigation, both associated with human population expansion in New Mexico, led to increased sediment deposition in the Middle Rio Grande. Sediment deposition exacerbated problems due to flooding and droughts, which led to a series ofpolitical and technological actions that progressively extirpated most of the large-bodied native fishes and all but one of the pelagic-spawning minnows. Restoration of the Middle Rio Grande and recovery of the endangered silvery minnow will require manychanges in the way humans use the river and its floodplain. If those changes occur, they should consider the Rio Grande within a landscape context that includes strategies for humans to live in arid regions without damaging fragile arid lands and theiraquatic ecosystems.