Ecosystems

1. Ecosystems Chapter 30

2. Bye-Bye Bayou • Louisiana’s coastal wetlands are disappearing • Global warming contributes to wetland’s demise • Sea levels rising worldwide • Burning fossil fuels raises global temperature

3. Impacts, Issues Video Bye-Bye, Blue Bayou

4. Ecosystem An array of organisms and their physical environment, interconnected through a one-way flow of energy and cycling of raw materials

5. Modes of Nutrition • Photoautotrophs • Capture sunlight or chemical energy • Primary producers • Heterotrophs • Extract energy from other organisms or organic wastes • Consumers, decomposers, detritivores

6. Simple Ecosystem Model Energy input from sun Producers Autotrophs (plants and other self-feeding organisms) Nutrient Cycling Consumers Heterotrophs (animals, most fungi, many protists, many bacteria) Energy output (mainly metabolic heat)

7. Simple Ecosystem Model The role of organisms in an ecosystem

8. SPRING Consumers • Herbivores • Carnivores • Parasites • Omnivores • Decomposers • Detritivores fruits insects rodents, rabbits birds SUMMER fruits rodents, rabbits insects birds seasonal variation in the diet of an omnivore (red fox)

9. Trophic Levels • Feeding relationships • All organisms at a trophic level are the same number of steps away from the energy input into the system • Autotrophs are producers • closest to energy input • first trophic level

10. Trophic Levels Fourth-level consumers (heterotrophs): 5th Top carnivores, parasites, detritivores, decomposers Third-level consumers (heterotrophs): 4th Carnivores, parasites, detritivores, decomposers Second-level consumers (heterotrophs): 3rd Carnivores, parasites, detritivores, decomposers First-level consumers (heterotrophs): 2nd Herbivores, parasites, detritivores, decomposers Primary producers (autotrophs): 1st Photoautotrophs, chemoautotrophs

11. fifth trophic level top carnivore (fourth-level consumer) marsh hawk fourth trophic level carnivore (third-level consumer) crow third trophic level carnivore (second-level consumer) garter snake second trophic level herbivore (primary consumer) cutworm first trophic level autotroph (primary producer) flowering plants Fig. 30-3, p.528

12. Food Chain Food chain

13. Food Chain marsh hawk • A straight-line sequence of who eats whom • Simple food chains are rare in nature upland sandpiper garter snake cutworm plants

14. marsh hawk Connections in a tallgrass prairie food web Higher Trophic Levels crow upland sandpiper garter snake frog weasel badger coyote spider Second Trophic Level sparrow prairie vole pocket gopher ground squirrel earthworms, insects First Trophic Level grasses, composites Fig. 30-4, p.529

15. Rain Forest Rain-forest food web

16. Energy Losses • Energy transfers are never 100% efficient • Some energy is lost at each step • Limits number of trophic levels in an ecosystem

17. Biological Magnification Nondegradable or slowly degradable substances become more and more concentrated in tissues of organisms at higher trophic levels of a food web

18. DDT in Food Webs • Synthetic pesticide banned in United States since 1970s • Carnivorous birds accumulate DDT in their tissues, produce brittle egg shells

19. Fig. 30-5, p.530

20. Ecological Pyramids • Primary producers are bases for successive tiers of consumers • Biomass pyramid • Dry weight of all organisms • Energy pyramid • Usable energy decreases as it is transferred through ecosystem

21. Biomass Pyramid • Aquatic ecosystem, Silver Springs, Florida • Long-term study of a grazing food web third-level carnivores (gar, large-mouth bass) 1.5 second-level consumers (fishes, invertebrates) 1.1 decomposers, detritivores (bacteria, crayfish) first-level consumers (herbivorous fishes, turtles, invertebrates) 37 primary producers (algae, eelgrass, rooted plants) 809 5

22. Energy Pyramid • Primary producers trapped about 1.2% of the solar energy that entered the ecosystem • 6–16% passed on to next level decomposers + detritivores = 5,080 21 top carnivores carnivores 383 herbivores 3,368 producers 20,810 kilocalories/square meter/year

23. Silver Springs Study Energy flow at Silver Springs

24. Biogeochemical Cycle • Flow of an essential substance from the environment to living organisms and back to the environment • Main reservoir is in the environment • Geologic processes, decomposers aid cycles

25. Three Categories • Hydrologic cycle • Water • Atmospheric cycles • Nitrogen and carbon • Sedimentary cycles • Phosphorus and other nutrients

26. Hydrologic Cycle atmosphere precipitation onto land 111,000 wind-driven water vapor 40,000 evaporation from land plants (evapotranspiration) 71,000 evaporation from ocean 425,000 precipitation into ocean 385,000 surface and groundwater flow 40,000 land ocean

27. Hydrologic Cycle Hydrologic cycle

28. Global Water Crisis • Limited amount of fresh water • Desalinization is expensive and requires large amounts of energy • Aquifers are being depleted • Groundwater is contaminated • Sewage, agricultural runoff, and industrial chemicals pollute rivers

29. Aquifer Problems Threats to aquifers

30. Carbon Cycle • Carbon moves through atmosphere, food webs, ocean, sediments, and rocks • Sediments and rocks are the main reservoir • Combustion of fossil fuels changes natural balance

31. Carbon Cycle Carbon cycle

32. Greenhouse Effect • Greenhouse gases impede escape of heat from Earth’s surface

33. Greenhouse Effect Greenhouse effect

34. Global Warming Long-term increase in temperature of Earth’s lower atmosphere

35. Greenhouse Gases Carbon dioxide and temperature

36. Carbon Dioxide Increase • Carbon dioxide levels fluctuate seasonally • Average level is steadily increasing • Burning of fossil fuels and deforestation are contributing to the increase

37. Other Greenhouse Gases • CFCs: synthetic gases used in plastics and in refrigeration • Methane: released by natural gas production, livestock • Nitrous oxide: released by bacteria, fertilizers, and animal wastes

38. Greenhouse Gases Greenhouse gases

39. Table 30-1, p.537

40. Nitrogen Cycle • Nitrogen is used in amino acids and nucleic acids • Main reservoir is nitrogen gas in the atmosphere • Nitrogen gas can’t enter food web

41. Nitrogen Cycle Nitrogen cycle

42. Human Effects • Humans increase rate of nitrogen loss by clearing forests and grasslands • Humans increase nitrogen in water and air by using fertilizers and by burning fossil fuels • Too much or too little nitrogen can compromise plant health

43. Air Pollution • Effects of nitrogen oxides released by burning fossil fuels

44. Deforestation Effect of air pollution in forests

45. Phosphorus Cycle • Phosphorus is part of phospholipids, nucleotides, NADH, ATP • Main limiting factor in ecosystems • Reservoir is Earth’s crust; no gaseous phase

46. Phosphorus Cycle Phosphorus cycle

47. Human Effects • In tropical countries, clearing lands for agriculture may deplete phosphorus-poor soils • In developed countries, fertilizer causes phosphorus overloads in soil

48. Eutrophication • Phosphorus is limiting factor in many freshwater ecosystems • Runoff from phosphate fertilizers accelerates algal growth in waterways • Resulting dense algal blooms cause system overload and death

49. Clouds Move

50. Stream