BSC 116 Lecture Notes - Lecture 41: Atmospheric Chemistry, Acid Rain, Invasive Species
4 Jun 2016
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Document Summary
Caused 73% of known extinctions: introduced exotic species. Increase in global travel led to increase in introduced species. Brown tree snake guam: 12 birds, 6 lizards extinct. Various insects introduced as biological controls: overexploitation. Example: hunting of elephants, rhinos, whales: global change. Human activates that cause habitat degradation and loss. Toxin accumulate in top predators, also a consequence of pollution. Human add lots of synthetic chemicals to ecosystems. Example: pesticides like ddt and industrial chemicals like pcb"s (polychlorinated biphenyls. Biological magnification: becomes more concentrated in higher trophic levels. Also release naturally occurring chemicals at unnatural levels. Mitigated by regulating waste, but can take a long time to degrade. Invasive species: an introduced species that established, expands its range, and has a substantial impact on native organisms and ecosystems. Example: brown tree snake on guam, make some birds and lizards extinct. Overexploitation: hunting, fishing, fisheries by catch, collecting for trade.
