Watershed Science – why bother? All landscapes organized into watersheds - PowerPoint PPT Presentation

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Watershed Science – why bother? All landscapes organized into watersheds

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  1. Watershed Science – why bother? • All landscapes organized into watersheds • watersheds within watersheds • Freshwater is an essential, limited resource • central to resource management issues • Streams important components of landscapes • interact with surrounding systems • physical & biological exchanges with the terrestrial • Energy & nutrients from terrestrial • Energy & nutrients to terrestrial • larger-scale, landscape approaches in ecology rapidly increasing

  2. 4. Cannot separate the stream from its valley (Hynes 1975) = watershed or landscape approaches 5. Freshwater biodiversity, particularly in streams, highly imperiled Dewatering (irrigation, etc.), pollution, impoundments Conservation Biology=rapidly growing field 6. Watershed science & stream ecology have made major contributions to basic & applied ecology Basic examples: trophic dynamics, factors governing diversity, whole ecosystem experiments, integration of physical & biological Applied examples: biological assessment, ecosystem management (vs. single species), disease control (Malaria, Schistosomiasis, etc.)

  3. Water used per year; does not include hydroelectric. Data from the USGS

  4. Data from the USGS

  5. Freshwater habitats, which are products of their watersheds, are some of the most diminished, degraded, and endangered in the world: water use: dewatering groundwater extraction surface water use & impoundment habitat destruction: draining wetlands destruction of headwaters modification of large rivers impoundments pollution: pesticides, thermal, metals, nutrients global change: temperature & precipitation altered hydrology altered thermal regimes

  6. Master 1990 Why is situation so much worse in freshwater habitats?

  7. Example: North American Mollusks Historically high diversity of freshwater mussels and snails in NA mussels/clams: 314 native species in NA 42 species federally endangered ~50% of mussel species imperiled or extinct gastropods: 659 species of FW snails in NA 9 federally endangered 200 species candidates for listing

  8. Why are freshwater mollusks disappearing? Mussels/clams changes in morphology & hydrology of streams siltation of habitats overexploitation (buttons, pearl culture) declines or restrictions to fish hosts exotic species (zebra mussel) Gastropods loss of wetlands general degradation of FW habitats (pollution, hydrology, etc.)

  9. Top 3 most at risk groups of animals in the US: Freshwater mussels ~69% extinct, critically imperiled, or vulnerable Crayfish ~51% extinct, critically imperiled, or vulnerable Stoneflies ~43% extinct, critically imperiled, or vulnerable Source: Nature Conservancy & Institute for Biodiversity

  10. Numbers of scientific papers on various freshwater groups from 1990-2005 (Strayer 2006)

  11. Numbers of described species of various freshwater groups

  12. Global fisheries production relying on freshwater in 2005 (Food and Agriculture Administration 2007)

  13. Colorado River Source: Rocky Mountains – 9000 ft. Delta: Baja & Sonora Mexico – Sea of Cortez Historically: Delta included 2 million acres of wetlands, lagoons, tide pools Today: river is dry before reaching Sea of Cortez! Hoover dam, Glen Canyon Dam, others – irrigation, hydroelectric irrigation (All American Canal - Imperial Valley in CA) industry, residential (Las Vegas, Phoenix – aqueducts)

  14. Salt water inlet River ends Sea of Cortez

  15. Colorado River Exotic Species Parasitic copepod Lernea cyprinacea Quagga mussel Dreissena bugensis Rainbow trout Oncorhynchus mykiss Channel catfish Ictalurus punctatus New Zealand mudsnail Potamopyrgus antipodarum