Env sci lecture5
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The document discusses key concepts in ecology such as ecosystems, energy flow, biogeochemical cycles, species interactions, and provides Lake Victoria and global climate change as case studies. It describes Lake Victoria's introduction of the Nile perch in 1960 and invasion of water hyacinth in 1990 that disrupted the ecosystem's balance. It also outlines the increasing levels of atmospheric CO2 and rising global temperatures due to human activities and some international efforts to address climate change such as the Kyoto Protocol.
Env sci lecture5
- 1. Chapter 5 How Ecosystems Work
- 2. Lake Victoria Freshwater lake in Africa Formerly home to ≈ 400 species of cichlids 1960: Nile perch introduced 1990: water hyacinth invaded Today, ecological imbalance; why?
- 3. What Is Ecology? Literally study of one’s “house” Interactions Two components Biotic Abiotic Broadest biological field of study
- 4. Ecological Organization Organism Population Community Ecosystem Landscape Biosphere
- 5. Goals Of Ecologists Understand how ecosystems function Make connections: landscape ecology Connections among ecosystems Great blue heron
- 6. Energy Capacity or ability to do work Flows through ecosystems Why do organisms need energy? Different kinds Potential energy Kinetic energy
- 7. First Law of Thermodynamics Energy cannot be created or destroyed Energy can be changed from one form to another
- 8. Second Law of Thermodynamics When energy is changed from one form to another, some is degraded into heat Heat is a less usable form of energy Increases entropy in the universe
- 9. Ecosystem Composition Producers Consumers Decomposers
- 10. Producers Make their own food Photosynthesis Examples? Lii L gh gh tt e enne errg gyy 6CO2 + 6H2O + ------> C6H12O6 + 6O2
- 11. Consumers Feed on other things Herbivores Carnivores Omnivores Detrivores
- 12. Decomposers Break down dead organisms and waste products Examples?
- 13. Energy Flow Energy passes from one organism to the next Trophic level: each step in this flow of energy Food chain: straight path Food web Interconnected food chains More realistic than food chain; why?
- 14. Food Chain
- 15. Food Web
- 16. Biogeochemical Cycles Matter cycles through ecosystems Five cycles Carbon Hydrologic (water) Nitrogen Sulfur Phosphorus
- 17. Carbon Cycle Essential component for life Gas (CO2) in atmosphere Several forms in ocean Can take a long time—think fossil fuels Photosynthesis Cellular respiration CO2 Sugar CO2
- 18. Carbon Cycle
- 19. Hydrologic Cycle Ocean Atmosphere Land Ocean
- 20. Nitrogen Cycle Proteins, DNA Atmosphere is 78% N2 Five steps Nitrogen fixation Nitrification Assimilation Ammonification Denitrification
- 21. Nitrogen Fixation Specialized bacteria Split atmospheric nitrogen and combine it with hydrogen
- 22. Nitrogen Cycle
- 23. Sulfur Cycle Underground sedimentary rocks and minerals Erosion releases compounds to ocean Volcanoes Essential component of proteins
- 24. Sulfur Cycle
- 25. Phosphorus Cycle No atmospheric component Phosphates used in DNA and ATP (chemical energy) Phosphates move through the food chain Land Organism Organism Land
- 26. Phosphorus Cycle
- 27. Ecological Niche Everything about an organism Adaptations Use of resources Lifestyle Habitat
- 28. Ecological Niche Two species cannot occupy the same niche: why? Resource partitioning Reduces niche overlap Reduces competition
- 29. Resource Partitioning At Work!
- 30. Species Interactions No species lives in complete isolation Symbiosis Intimate relationship between members of at least 2 species Mutualism, commensalism, parasitism Result of coevolution Other interactions Predation, competition
- 31. Mutualism Both species benefit
- 32. Commensalism One species benefits, other not affected
- 33. Parasitism Parasite benefits, host is “harmed” Ectoparasites & endoparasites
- 34. Species Interactions Predation: consumption of one species by another Coevolution: “arms race”
- 35. Avoiding Predators Mechanical defenses Social groups Camouflage Protective chemicals
- 36. Species Interactions Competition: two or more organisms attempting to use the same resource Intraspecific vs. interspecific
- 37. Keystone Species Crucial to maintenance of an ecosystem Loss affects many other species Examples? This idea is being challenged; why?
- 38. Case Study: Global Climate Change Atmospheric CO2 increased dramatically. Why? 10 warmest years have occurred since 1990 2005 warmest 1998 second warmest 2002 third warmest Earth’s temperatures may rise 1.8o – 4.0o C (3.2o – 7.2o F) by end of 21st century What could occur?
- 39. Case Study: Global Climate Change Kyoto Protocol – International climate change conference – Kyoto, Japan 1997 Highly developed countries to cut CO2 emissions ~ 5.2% by 2012 US Department of Energy Automotive vehicles designed for better gas mileage High efficiency wind turbines