Learning Targets 20. Explain how habitat destruction, invasive species, and overexploitation lead to a loss of species. 21. Describe how human population size relates to the impact humans have on the environment. 22. Describe the causes of major environmental issues. (Climate Change, Ozone depletion, Acid rain, Eutrophication, Biological magnification)

Biodiversity ALL organisms in the ecosystem—with all possible gene variants One of Earth’s greatest resources! Threats Endangered Species Threatened Species

Threats to Biodiversity Habitat fragmentation Habitats isolated— organisms can’t breed Smaller the habitat → fewer species Biological magnification Toxic substances become more concentrated as they pass through food chain DDT & Rachel Carson

Threats to Biodiversity (cont.) Introduced species Invasive species— reproduce rapidly & outcompete natives Zebra mussels! Thistle, purple loosestrife, kudzu

Other problems Ozone depletion CFC’s degraded atmospheric ozone— lets too much UV in → cancers Global warming Greenhouse gases -- cause atmosphere to warm up, ice shelves melt, deserts spread

Resource Management Renewable Resources Can be regenerated or replenished Non-renewable Resources Cannot be replaced Ex. Fossil fuels Sustainable development Using resources without using them up No overexploitation

Resource Management: Conservation Habitat protection Protect Keystone species Species that can crash the ecosystem Understand edge effect Reduces habitat in wooded areas Quail, pheasant Habitat restoration

Land Resources Erosion Plowing leaves soil exposed—erodes Loss of fertile topsoil Results in desertification

Forest Resources Provide wood, oxygen, niche for many organisms Deforestation Loss of wood/oxygen & biodiversity Erosion of soil

Fishery Resources HUGE food resource Overfishing will eliminate food fish by mid-century & crash ocean ecosystems Solution: Aquaculture—grow food fish! Not problem free