Aquatic Ecosystem Services

Aquatic Ecosystem Services - Lecture 18 Aquatic Ecosystem...

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Unformatted text preview: Lecture 18 Aquatic Ecosystem Services EVPP/BIO L 350 Ecosystem Services What products and services do freshwater ecosystems provide us? Some Ecosystem Services water supplies for irrigation, industries, cities, and homes; fish, waterfowl, mussels, and other foods for people and wildlife water purification and filtration of pollutants flood mitigation drought mitigation groundwater recharge water storage wildlife habitat and nursery grounds soil fertility maintenance delivery of nutrients to deltas and estuaries delivery of freshwater flows to maintain estuarine salinity balances recreational opportunities aesthetic, cultural, and spiritual values conservation of biodiversity, which preserves resilience and options for the future. Source : Sandra Postel (2005), Liquid Assets: the Critical Need to Safeguard Freshwater Ecosystems Human Impacts What human activities impact freshwater ecosystems and their services? Human Activities Impact Freshwater Ecosystem Services Human Activity Impact on Freshwater Ecosystem Services? Land conversion and degradation Dam construction Dyke and levee construction Large-scale river diversion Groundwater withdrawals Uncontrolled pollution Emissions of climate-altering air pollutants Introduction of exotic species Population and consumption growth Source : Sandra Postel (2005), Liquid Assets: the Critical Need to Safeguard Freshwater Ecosystems Land conversion and degradation Impacts Worldwide, half or more of the land in nearly one-third of 106 primary watersheds has been converted to agriculture or urban-industrial uses. Thirteen Europeans watersheds have lost at least 90% of their original vegetative cover. An estimated 25-50% of the worlds original wetlands area has been drained for agriculture or other purposes- Alters partitioning of rainfall between surface runoff, groundwater recharge, and evapotransporation- Affects quantity, quality, and/or timing of water flows- Causes sedimentation of reservoirs- Causes habitat degradation and species loss Human Activities Impact Freshwater Ecosystem Services Dam construction Impacts Engineers have built more than 45,000 large dams on the worlds rivers, up from 5,000 in 1950 an average construction rate of two large dams per day Dams now affect more than half of the worlds large river systems (172 out of 292) and more than three- quarters of large river systems in the United States, Canada, Europe, and the former Soviet Union- Fragments rivers and alters natural flow patterns. Dams and reservoirs now intercept about 35% of river flows as they head toward the sea, up from 5% in 1950. They can hold back 15% of annual global runoff all at once- Changes water temperature and nutrient and sediment transport....
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Aquatic Ecosystem Services - Lecture 18 Aquatic Ecosystem...

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