Bio171-F08-lec%207

Bio171-F08-lec%207 - Lecture 7 Global Warming Biology 171...

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Unformatted text preview: Lecture 7: Global Warming Biology 171 Wednesday September 17, 2008 Today’s Topics: Announcements This Week in Discussion: Global Warming Text Reading: Lecture 7: 2 nd ed: Chapter 54 (1259-1261) 3 rd ed: Chapter 54 (1238-1241) Lecture 8: 2 nd ed: Chapter 53 (1214-1220) 3 rd ed: Chapter 53 (1196-1202) Bioamplifcation Carbon Cycle Fossil Fuels & Industrialization Greenhouse Gases Our Present Day Situation Possible Future Scenarios Di¡fcult Choices A local example of a food web: Avian botulism in Michigan Since the late 1990’s, hundreds of thousands of birds have died along the Great Lakes shorelines due to botulism poisoning. The Players: Clostridium botulinum – anaerobic, gram-negative bacterium Role in ecosystem: decomposer. Also produces the most toxic natural substance known to humans – botulinum toxin (aka Botox). The Players: Anabaena spp. – photosynthetic cyanobacterium (and other Cyanobacteria and eukaryotic algae. Role in ecosystem: producer. Dense populations form large floating mats or scums. The Players: Dreissena spp. – Zebra and quagga mussels. Introduced from Europe/W. Asia in ship ballast water. First seen in Great Lakes in 1988 & 1990 respectively. Role in ecosystem: primary consumer. Filter phytoplakton and bacteria from water. The Players: Neogobius melanostomus – Round goby. Introduced from Europe/W. Asia in ship ballast water. First seen in Great Lakes in 1995. Now endangered in native range. Role in ecosystem: secondary consumer. Feeds largely on zebra and quagga mussels. The Players: Gavia immer, Larus ridibundus, Mergus merganser – Common loon, ring-billed gull, common merganser – native birds. Role in ecosystem: secondary/tertiary consumer. Feed on fish. The food web: The botulinum toxin moves up the food chain, poisoning fish and then birds. This is similar to the Bioamplification of certain toxic chemicals, such as pesticides, that concentrate at higher trophic levels. Chemicals such as DDT were ultimately banned because of the damage they did to apex predators such as falcons and eagles. Global Biogeochemical Cycles When nutrients leave one ecosystem, they enter another. The movement of ions and molecules among ecosystems links local biogeochemical cycles into one massive global system. Broader Implications of Ecosystem Nutrient & Energy Dynamics The atoms (chemical nutrients) that constitute our bodies at any one point in time were previously part of other organisms/inanimate objects and, as we respire and eventually die, they will continue to be recycled indefinitely. The metabolic energy we are presently using left the sun a few weeks-years ago in the form of photons and will shortly radiate back to space as heat....
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This note was uploaded on 01/30/2012 for the course BIO 171 taught by Professor Josephinekurdziel during the Fall '08 term at University of Michigan.

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Bio171-F08-lec%207 - Lecture 7 Global Warming Biology 171...

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