General Biology 1004 Chapter 20 Lecture Handout, Summer 2005 Dr. Frisby

Transcription

1 Slide 1 CHAPTER 20 Human Impact on the Environment PowerPoint Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Neil Campbell, Jane Reece, and Eric Simon Presentation prepared by Chris C. Romero Slide 2 BIOLOGY AND SOCIETY: AQUARIUM MENACES In May 2002 in Maryland, a fisher caught and released an exotic looking fish, which was identified as the northern snakehead Figure 20.1a Slide 3 The northern snakehead Is a fish native to eastern Asia Was accidentally introduced into Maryland Introduced species Can severely disrupt ecosystems

2 Slide 4 The seaweed Caulerpa Was accidentally introduced into the United States, probably after being dumped from a home aquarium Has caused significant problems and competes with native species Figure 20.1b Slide 5 HUMAN IMPACT ON BIOLOGICAL COMMUNITIES Human disturbance of biological communities is almost always destructive Slide 6 Human Disturbance of Communities Of all animals, humans have the greatest impact on communities worldwide Figure 20.2

3 Slide 7 Human disturbance usually reduces species diversity in communities Much of the United States is now a hodgepodge of early successional growth where more mature communities once prevailed Slide 8 Introduced Species Introduced species Slide 9 Kudzu, a Japanese plant Was introduced into the United States in 1930 as a means of erosion control Has taken over vast expanses of the southern landscape Figure 20.3a

4 Slide 10 The European starling Was introduced into the United States by a group intent on introducing all the plants and animals mentioned in Shakespeare s plays Has displaced many native songbirds Figure 20.3b Slide 11 Argentine ants Were accidentally introduced into the United States Have decimated populations of native ants in California Figure 20.3c Slide 12 The zebra mussel Was accidentally introduced into the United States, probably in ballast water from a cargo ship Has caused significant problems and competes with native species Figure 20.3d

5 Slide 13 HUMAN IMPACT ON ECOSYSTEMS Human population growth and technology add up to a badly bruised biosphere Slide 14 Burning of fossil fuels is likely causing global warming Figure 20.4 Slide 15 Impact on Chemical Cycles Human activities Often intrude in biogeochemical cycles by removing nutrients from one location and adding them to another

6 Slide 16 Impact on the Carbon Cycle The increased use of fossil fuels Slide 17 Impact on the Nitrogen Cycle Sewage treatment facilities and fertilizers Slide 18 Impact on the Phosphorous Cycle Sewage treatment facilities and fertilizers

7 Slide 19 Impact on the Water Cycle Destruction of tropical rain forest Figure 20.5 Slide 20 To irrigate crops, humans pump large amounts of ground water to the surface Deforestation and extensive removal of ground water change the water cycle Slide 21 Deforestation and Chemical Cycles: A Case Study The Hubbard Brook Experimental Forest is a study site for chemical cycling in a forest ecosystem

8 Slide 22 Researchers have monitored water and mineral loss by damming parts of a creek in the forest Figure 20.6a Slide 23 One area of the forest was logged and sprayed with herbicides, and the inflow and outflow of water and minerals were compared to those of a control watershed Figure 20.6b Slide 24 Net losses of minerals from the altered area were huge, exhibiting the impact of human activity on a forest ecosystem Altered Completion of tree cutting Control Figure 20.6c

9 Slide 25 The Release of Toxic Chemicals to Ecosystems Humans have added to ecosystems new toxic materials, which often cannot be degraded by microorganisms Slide 26 Toxic substances Slide 27 Biological magnification DDT concentration increase of 10 million times DDT in fish-eating birds 25 ppm DDT in large fish 2 ppm DDT in small fish 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water ppm Figure 20.7

10 Slide 28 Human Impact on the Atmosphere and Climate It was once thought that the atmosphere could absorb the variety of gaseous waste products produced by humans Figure 20.8 Slide 29 Carbon Dioxide Emissions, the Greenhouse Effect, and Global Warming Since the Industrial Revolution, the concentration of CO 2 in the atmosphere has been increasing due to the burning of fossil fuels and wood and to deforestation Figure 20.9 Slide 30 The greenhouse effect

11 Slide 31 Light Greenhouse effect: CO2 lets sunlight through but retains the heat it generates Adding CO2 to the air increases the greenhouse effect Heat CO2 Removal of CO2 from the air by photosynthesizing plants and algae decreases the effect CO2 CO2 Figure Slide 32 The marked increase in atmospheric CO2 could cause an increase in global temperatures, with potentially disastrous consequences Global warming projections Figure Slide 33 Developed countries

12 Slide 34 Depletion of Atmospheric Ozone The ozone layer Slide 35 The protective ozone layer (a) Ozone hole (b) Thickness of ozone layer Monthly averages for October Figure 20.12a, b Slide 36 The consequences of ozone depletion May be quite severe for all life on Earth, including humans Figure 20.12c

13 Slide 37 THE BIODIVERSITY CRISIS The effect of human activity on communities and ecosystems is an alarming biodiversity crisis, a precipitous decline in Earth s great variety of life Slide 38 The Three Levels of Biodiversity Biodiversity has three main components Slide 39 The first is the diversity of ecosystems The second is the variety of species that make up the biological community of any ecosystem Figure 20.13

14 Slide 40 The third is the genetic variation within each species Slide 41 The Loss of Species The current mass extinction Is being caused by human activity Is broader and faster than other past extinctions Slide 42 We do not know the full scale of the biodiversity crisis; however, there are enough signs to know that the biosphere is in deep trouble

15 Slide 43 11% of the known bird species in the world are endangered Of the 20,000 known plant species in the United States, over 600 are very close to extinction Throughout the world, 970 tree species have been classified as critically endangered About 20% of the known freshwater fishes in the world have become extinct or are seriously threatened Slide 44 Biologist Edward O. Wilson has compiled the Hundred Heartbeat Club, which includes species of animals that number fewer than a hundred individuals Figure Slide 45 Several researchers estimate that at the current rate of destruction, over one half of all plant and animal species will be gone by the end of this new century

16 Slide 46 The Three Main Causes of the Biodiversity Crisis Habitat Destruction Human alteration of habitat Poses the single greatest threat to biodiversity throughout the biosphere Figure 20.15a Slide 47 Introduced Species Human introduction of exotic species Figure 20.15b Slide 48 Overexploitation Overexploitation of wildlife Figure 20.15c

17 Slide 49 Why Biodiversity Matters Humans rely on biodiversity for Figure Slide 50 The loss of diversity Slide 51 CONSERVATION BIOLOGY Conservation biology

18 Slide 52 Biodiversity Hot Spots A biodiversity hot spot Slide 53 Equator Tropical forest hot spots Chaparral hot spots Slide 54 Endemic species Figure 20.17

19 Slide 55 Conservation biologists Slide 56 Conservation at the Population and Species Levels Much of the discussion of the biodiversity crisis centers on species Slide 57 The U.S. Endangered Species Act

20 Slide 58 Habitat Fragmentation and Subdivided Populations Population fragmentation Figure Slide 59 Fragmentation usually results in Slide 60 Subpopulations A source habitat

21 Slide 61 A sink habitat Dispersal of individuals to sink habitats because of habitat loss can sometimes threaten the survival of subpopulations in source habitats Slide 62 What Makes a Good Habitat? Identifying the specific combination of habitat factors that is critical for a species is fundamental to conservation biology Slide 63 The red-cockaded woodpecker Figure 20.19a

22 Slide 64 Certain habitat factors are necessary for these birds Figure 20.19b Slide 65 A habitat that has become a sink has thick and tall undergrowth Figure 20.19c Slide 66 Conserving Species amid Conflicting Demands Conservation biology

23 Slide 67 Competing demands for habitat are almost always an issue Slide 68 Conservation at the Ecosystem Level Conservation biology Landscape ecology Slide 69 Edges and Corridors Edges between ecosystems Figure 20.20a

24 Slide 70 Can be created by humans Can have both positive and negative effects on biodiversity Figure 20.20b Slide 71 A movement corridor An artificial corridor Figure Slide 72 Corridors Can promote dispersal and help sustain populations Are especially important to species that migrate between different habitats

25 Slide 73 Zoned Reserves A zoned reserve Slide 74 Nicaragua Caribbean Sea Llanuras de Tortuguero Costa Rica Guanacaste Arenal La Amistad Bajo Tempisque Cordillera Volcanica Central Pacifico Central Peninsula de Osa Pacific Ocean Panama Figure 20.22a Slide 75 The areas surrounding zoned reserves are buffer zones that support sustainable agriculture and tourism Figure 20.22b

26 Slide 76 The Goal of Sustainable Development Sustainable development The goal of sustainable development Slide 77 EVOLUTION CONNECTION: BIOPHILIA AND AN ENVIRONMENTAL ETHIC Edward O. Wilson makes the case that biophilia, the human desire to affiliate with other life in its many forms, is innate Figure Slide 78 Most biologists Have embraced the concept of biophilia Have turned their passion for nature into careers Figure 20.24

27 Slide 79 SUMMARY OF KEY CONCEPTS The Release of Toxic Chemicals to Ecosystems Increasing DDT concentration Visual Summary 20.1 Slide 80 The Three Levels of Biodiversity Diversity of ecosystems Diversity of species within communities Diversity within species Visual Summary 20.2 Slide 81 The Three Main Causes of the Biodiversity Crisis Habitat destruction Introduction of non-native species Overexploitation of wildlife Visual Summary 20.3

28 Chapter 20 Study Objectives 1. Explain how the northern snakehead fish and the Caribbean alga Caulerpa were introduced into a new environment. Explain why these introductions were significant. 2. Explain how humans impact natural communities all over the world. 3. Explain why most introduced species cause environmental problems. 4. Describe at least three examples of deliberate and at lease three examples of accidental introductions of exotic species into the United States. Describe the impacts of each introduction. 5. Explain why introduced species are often able to outcompete native organisms. 6. Describe how human activities have disrupted the carbon, nitrogen, phosphorus, and water cycles. 7. Describe the research at the Hubbard Brook Experimental Forest, and explain what we have learned from this project. 8. Explain how biological magnification concentrates toxins in the highest trophic levels. 9. Explain how burning threes after deforestation and the use of fossil fuels contributes to global warming. Describe the possible consequences of global warming. 10. Explain how the use of chlorofluorocarbons contributes to the depletion of the ozone layer. Describe the possible consequences of the depletion of the ozone layer. 11. Describe the three levels of biological diversity. 12. Explain how the current mass extinction compares of the Cretaceous extinction. 13. Describe the three main causes of the biodiversity crisis. 14. Explain why biodiversity matters. 15. Explain the importance of biodiversity hot spots to the conservation of biological diversity. 16. Distinguish between endangered and threatened species. 17. Explain how habitat fragmentation impacts a species. 18. Describe the nature of the issues confronting modern conservation biology. 19. Explain how edges, corridors, and zoned reserves are important to the conservation of landscapes. 20. Describe the goals of sustainable development. 21. Describe the concept of biophilia.