Transcript Document
ECL 6080: August 27, 2009 - C. M. Pringle Declining Freshwater Biodiversity: Canaries in the Coal Mine 1. Genetic, species and ecosystem-level declines and effects on products and ecosystem services 2. Major threats to freshwater biodiversity a) physical b) chemical c) biological FW Biodiversity in Peril • There are ~100,000 FW species in 14 phyla – but no comprehensive analysis of their status exists • 30% of ~10,500 fish species threatened mostly by habitat destruction • In North America, the extinction rate of FW organisms is 5X that of terrestrial fauna • An extinction rate of 4% per decade is expected for the future – and likely greater in tropical regions • Loss rates for system-level processes not known HIERARCHICAL LEVELS of biodiversity Landscape Communities & ecosystems Populations & species Genetic Ward et al. 1999 Genetic-level • Destruction and loss of genetically distinct populations e.g., salmonids • Isolation of populations • Hatchery-reared fish Species-level • Loss of native species (accelerating rates of loss) -crayfish (51%) -mussels (69%) -fishes (37%) ----------------------mammals (13%) -birds (11%) • Extirpation of native species over much of their original range • Increasing numbers of exotic species Aquatic species at risk > 15% 10-15% 5-9% < 5% Includes mussels, crayfish, fishes, amphibians, reptiles, mammals and birds Modified from TNC (1997) Ecosystem-level Measuring the losses: -the US has lost over half of the wetlands that existed at the time of the American Revolution -Iowa retains only 1% of its natural marshes/prairie potholes; North Dakota-40%; Minnesota 47%; South Dakota 65% -Less than a quarter of bottomland hardwood forests remain in the midwest and the southern US -Much riparian habitat in arid regions of the US has been destroyed (<5% remains of original habitat in Arizona -Of 3.2 million miles of streams in the lower 48 states, only 2% of rivers are free-flowing and relatively undeveloped. Only 42 free-flowing rivers exist of over 125 or more miles in length. The other 98% of US streams have been developed Products/Ecosystem Services • Products -harvests of fishes and mussels • Water purification -oysters -wetlands -riparian buffer zones • Buffering the impact of floods Threats to freshwater ecosystems • Physical -dams -water abstraction (irrigation, groundwater pumping) -land-use change • Chemical -nutrients, toxics, persistant organic chemicals (PCBs), endocrine disruptors, pharmaceuticals • Biological -invasive species (competition, hybridization) Synergistic interactions between above PHYSICAL THREATS •Regulation (dams) •Water diversion •Groundwater exploitation Source: USACE (J. Jordan photo) DAMS Water diversions and abstraction Irrigation Soil salinization The shrinking Aral Sea 1964 (left) and 1997 (right) N N Interbasin transfers threaten endemic taxa by promoting faunal exchange (diffusion of diverse communities that were previously isolated) and hybridization Insert water diversio n map CHEMICAL THREATS Point Source and Non-point Source Nutrient and Toxic Loading Emerging threats: • Endocrine Disruptors • Pharmaceuticals • Coastal Dead Zones Pesticides Source: USACE Pesticide runoff potential Watershed Qualification Low potential for runoff Moderate potential for runoff High potential for runoff Insufficient data Source: USEPA (1998) Global scale hydrologic connectivity and the transport of PCBs: Effects on arctic food webs News Item: Estrogen imitating chemicals in the environment suspected of wide-ranging biological anomalies, including hermaphrodism in animals and lower sperm count in human beings… We in the business community prefer a more cautious “wait- and-see” approach over senseless media scare-mongering... Source: G. Olson Land-use and related chemical and physical threats to freshwater biodiversity Concentrated Animal Operations Source: NRCS URBANIZATION Photos: R. Bjorkland Impervious surfaces • • • • Increase volume Increase speed Increase pollutants Decrease infiltration Photo: R. Bjorkland BIOLOGICAL THREATS: EXOTIC SPECIES Number of introduced species 600 Temporal trends nationwide 500 400 300 200 100 0 1850-1900 1901-1950 Native to the US Foreign 1951-1996 Source USGS NAS (1998) BIOLOGICAL Threats Photo: L. Nico ( USGS) Photo: K. Schimdt Photo: Great Lakes Sea Grant Network Exotic Species Graphics Library Photo: D. Ingrao (Mote Marine Lab., Sarasota, FL) Exotics threaten native species • • • • Predation Genetic swamping Competition Diseases and parasites Source: USFWS Major Gaps and Uncertainties (Challenges to protecting freshwater biodiversity) • Scaling from catchments to the globe • Understanding biocomplexity • Identifying ‘hotspots’ of endemicity for major taxonomic groups • Understanding and forecasting the ecological consequences of water cycle alterations – goods & services and human health • Separating climate from land use changes • Optimizing multiple uses We forget that the water cycle and the life cycle are one Photo: R. Bjorkland In the end we may need a new water ethic, in a sense an ethic that says it’s important now to begin sharing water with each other as well as with nature Sandra Postel Source: US Navy Why is the biodiversity of aquatic ecosystems disproportionately affected relative to terrestrial ecosystems? Hydrologic connectivity: Water-mediated transfer of matter, energy, and/or organisms within or between elements of the hydrologic cycle Pringle. 2001. Hydrologic connectivity and the management of biological reserves: A global perspective. Ecological Applications 11:981-98.