Threats to Biodiversity
Habitat Loss Happens when either natural disasters or human activities change the ecosystem so much that many species can no longer survive. Natural sources of habitat destruction: Volcanic eruptions Wildfires Droughts Severe storms Human activities: Deforestation Draining wetlands Damming rivers
Deforestation Forests can be logged or cleared and never replanted. Annual deforestation rates in North America are almost three times the average rate worldwide since 1966.
Draining Wetlands Wetlands cover 6% of Earth’s surface Plants, turtles, snakes, mink and 1000’s more live in wetlands Migrating birds use them to feed and rest Plants that grow there filter sediment and pollution from water. Often drained for farming or building homes. 90% of wetlands around lake Ontario have been destroyed.
Alien Species Alien species: is accidentally or deliberately brought into a new location. Introduced species, non-native species, exotic species. Sometimes they can become an invasive species which is a species that takes over the habitat of native species and upsets the equilibrium of an ecosystem.
Zebra Mussels Native to Asia Introduced to Great Lakes through ballast water Ballast water is when cargo ships pick up water to keep them stable at sea and then dump the water in other places. Zebra mussels out- competed native crustaceans, which in turn were a major source of food for whitefish and smelt
Round Gobies Asian Round Goby also probably came in ballast water Population grew exponentially since 1990’s. We’re not sure of their impact yet, but their population is estimated in the billions in Lake Erie.
Overexploitation The use or extraction of a resource until it is depleted. Examples: Passenger pigeon once 5 billion, last one died in 1900’s. Yellowfish tuna and Atlantic cod: over-fished and reduced by 90%
Extinction When all individuals of a species dies. When death rate exceeds birth rate over a long period of time. There are patterns of extinction that happened naturally: Background extinction: apparent over long periods as ecosystems change, some species become extinct Mass extinction: relatively sudden ecosystem change. Example: dinosaurs (caused by an asteroid?)
Restoration Ecology
Environmental Stewardship The assumption of responsibility for the welfare of the environment All humans are responsible. In history, most humans have not thought about sustaining ecosystems Now, more and more we are concerned with the renewal of degraded or destroyed ecosystems through human intervention (restoration ecology) The assumption of responsibility for the welfare of the environment All humans are responsible. In history, most humans have not thought about sustaining ecosystems Now, more and more we are concerned with the renewal of degraded or destroyed ecosystems through human intervention (restoration ecology)
Methods of Restoration Reforestation: the regrowth of a forest, naturally or by planting trees or seeds in an area where a forest was cut down. Wetlands Restoration: water returned to natural levels, soil quality returned. Bioremediation: using living organisms to clean up contaminated areas –Plants that clean up contaminants in soil –Bacteria that clean up oil spills Bioaugmentation: use organisms to add essential nutrients to soil –Clover added to replenish nitrogen Reforestation: the regrowth of a forest, naturally or by planting trees or seeds in an area where a forest was cut down. Wetlands Restoration: water returned to natural levels, soil quality returned. Bioremediation: using living organisms to clean up contaminated areas –Plants that clean up contaminants in soil –Bacteria that clean up oil spills Bioaugmentation: use organisms to add essential nutrients to soil –Clover added to replenish nitrogen
Controlling Alien Species Biocontrol: use one species to control another undesired species. Chemicals: like poisoning, it kills the species. Biocontrol: use one species to control another undesired species. Chemicals: like poisoning, it kills the species.