Biodiversity

• Weed invasions of natural ecosystems are among the greatest environmental threats facing temperate Australia
• High biodiversity means a large number of different species in an ecosystem
• An ecosystem with high biodiversity is less likely to be disrupted by environmental changes
• Chemical pesticides can have harmful effects beyond insects
• Habitat destruction is damage done to the factors an organism depends on for survival within its habitat
• In the 1970s, research found that DDT was present in all organisms in a food chain, with concentrations increasing up the food chain
• Biodiversity includes both flora (plants) and fauna (animals)
• DDT was the first modern synthetic insecticide developed in the 1940s
• Weeds degrade natural environments by competing with and displacing native vegetation, affecting the fauna of invaded ecosystems
• Weeds invading an ecosystem

  It is much harder for weeds to invade a community with high biodiversity compared to a community with low biodiversity
• Animals affected by habitat destruction

  • bilby, woylie, rat kangaroo, potoroo, Regent honeyeater
• Research found that DDT was present in all organisms in a food chain

  1970’s
• DDT accumulated in humans, especially breast milk, and was linked to diseases such as cancer, diabetes, hormonal disruption, and reproductive problems
• The accumulation of DDT had serious effects on some types of birds, especially those at the end of the food chain (such as peregrine falcons and eagles)
• If pesticides drift away from crops or are used incorrectly, useful insects like bees and predatory wasps can be killed
• Many poorer countries continue to use DDT, particularly those with a malaria problem
• Increased production of carbon dioxide by human activities contributes to global warming
• Overcropping of animal populations results in a decrease in the population, as seen in the decline of many whale populations
• Many governments are trying to limit emissions of greenhouse gases, especially carbon dioxide, to address global warming
• DDT caused birds to lay eggs with thin shells, leading to fewer young being produced and a decrease in the population
• T (dichloro-diphenyl-trichloroethane) was developed as the first of the modern synthetic insecticides in the 1940s
• DDT was banned in Australia

  1987
• Levels of pesticides increase up the food chain

  Resulting in high concentrations in the top-order consumers
• Not all pesticides accumulate in organisms like DDT, but they can still cause problems if not used carefully
• Many scientists argue that carbon dioxide is polluting the Earth’s atmosphere and causing global warming
• Raising the Earth’s temperature may lead to the melting of polar ice caps, causing sea levels to rise and changing wind and rainfall patterns
• Aboriginal people, fire, and ecosystems have a positive impact on biodiversity and Australian ecosystems
• Oil spills from ships can cause devastation to sea ecosystems