Human Biology Sylvia S. Mader Michael Windelspecht Chapter 23 Global Ecology and Human Interferences Lecture Outline See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Points to Ponder What is an ecosystem and what are its biotic components? What are the energy flow and chemical cycling in an ecosystem? What are the two major ecosystems on earth? Describe the 3 types of terrestrial ecosystems and the 2 types of aquatic ecosystems. Compare and contrast food webs and food pyramids. What is a biogeochemical cycle? What is a reservoir and an exchange pool. Explain the water, carbon, nitrogen, and phosphorus cycles. What human activities interfere with these cycles? What problems are we creating by altering these pathways? What is ozone depletion and why is this important? What are the pros and cons to drilling in the Arctic National Wildlife refuge?
23.1 The nature of ecosystems The nature of ecosystems Biosphere the regions of the Earth s waters, crust, and atmosphere inhabited by living organisms Ecosystem a place where organisms interact between each other and their environment Terrestrial: several distinct types based on temperature and waterfall Aquatic: freshwater and marine
23.1 The nature of ecosystems Terrestrial ecosystems Forests dominated by trees Tropical rain forest Coniferous forests (taiga) Temperate deciduous forests Grasslands dominated by grass Tropical grasslands Temperate grasslands (prairie) Deserts characterized by lack of available moisture Tundra Deserts
23.1 The nature of ecosystems Terrestrial ecosystems Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. temperate forest temperate forest desert desert tropical rain forest tropical rain forest tropical grassland (savanna) tropical grassland (savanna) temperate grassland (prairie) temperate grassland (prairie) taiga taiga autumn tundra winter tundra (temperate, desert, rain forest, prairie): Corbis RF; (savanna): Gregory Dimijan/Photo Researchers, Inc.; (taiga): Brand X Pictures/PunchStock RF; (autumn tundra): Joseph Van Os/Getty Images; (winter tundra): Oxford Scientifi c/getty Images
23.1 The nature of ecosystems Marine Seashores Oceans Coral reefs Estuaries Aquatic ecosystems Freshwater Lakes Ponds Rivers Streams
23.1 The nature of ecosystems Aquatic ecosystems
23.1 The nature of ecosystems Components of an ecosystem Abiotic components nonliving environment Biotic components - living components Autotrophs producers Heterotrophs consumers Herbivores feed on plant and algae Carnivores feed on other animals Omnivores eat both plants and animals Detritus feeders feed on decomposing organic matter Niche the role an organism plays in an ecosystem such as how it gets its food, what it eats, and how it interacts with other organisms
23.1 The nature of ecosystems Biotic components of an ecosystem
23.1 The nature of ecosystems Energy flow and chemical cycling Energy flow: Begins and continues when producers absorb solar energy Occurs as nutrients pass from one population to another This energy is converted to heat that dissipates into the environment Only a portion of energy is passed to organisms as they consume one another Chemical cycling: Inorganic nutrients are returned to producers from the atmosphere or soil Chemicals recycle within and between ecosystems
23.1 The nature of ecosystems Energy flow and chemical cycling Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. solar energy heat producers consumers inorganic nutrient pool heat heat decomposers energy nutrients
23.1 The nature of ecosystems Fate of food energy taken in by a herbivore Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Heat to environment growth and reproduction Energy to carnivores Energy to detritus feeders George D. Lepp/Photo Researchers, Inc.
23.2 Energy flow Energy flow Food web describes who eats whom Grazing food web Detrital food web Trophic levels composed of all organisms that feed at a particular link in the food chain Producers, primary consumers, and secondary consumers Ecological pyramid reflects the loss of energy from one trophic level to another Only about 10% of the energy of one trophic level is available to the next trophic level
23.2 Energy flow Food webs Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Autotrophs (Producers) Herbivores/Omnivores Carnivores fruits and nuts birds hawks owls leaf-eating insects deer foxes leaves rabbits chipmunks detritus skunks detritus snakes detritus mice mice a. grazing food web fungi and bacteria (decomposers) invertebrates (earthworms) carnivorous invertebrates (beetles) salamanders shrews b. Detrital food web
23.2 Energy flow An example of a food pyramid Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. top carnivores 1.5g/m 2 carnivores 11g/m 2 herbivores 37g/m 2 producers 809g/m 2
23.3 Global Biogeochemical cycles Biogeochemical cycles Biogeochemical cycles are pathways by which chemicals circulate through an ecosystem including both living and nonliving components 1. Water cycle 2. Carbon cycle 3. Nitrogen cycle 4. Phosphorus cycle Reservoir fossil fuels, minerals in rocks, and sediment in oceans that contain inorganic nutrients that are limited in availability Exchange pools atmosphere, soil, and water that are ready sources of inorganic nutrients
23.3 Global Biogeochemical cycles Biogeochemical cycles Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Reservoir fossilfuels mineral in rocks sediment in oceans Exchange Pool atmosphere soil water Community
23.3 Global Biogeochemical cycles Water cycle Water evaporates from the bodies of water, land, and plants and returns when water falls on land to enter the ground, surface waters, or aquifers Human activities that interfere: Withdraw water from aquifers Clear vegetation from the land and build structures that prevent percolation and increase runoff Add pollutants to water such as sewage and chemicals
23.3 Global Biogeochemical cycles Water cycle Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H 2 O in Atmosphere transport of water vapor by wind 3 transpiration from plants and evaporation from soil 2 precipitation over land lake 1 2 evaporation from ocean precipitation to ocean 5 fresh water runoff Ice Ocean 6 aquifer 4 Groundwaters
23.3 Global Biogeochemical cycles Carbon cycle CO 2 is exchanged between the atmosphere and living organisms Plants incorporate atmospheric CO 2 into nutrients through photosynthesis that can be used by living organisms CO 2 is returned to the atmosphere through respiration
23.3 Global Biogeochemical cycles Carbon cycle Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 7 combustion CO 2 in Atmosphere 1 photosynthesis 2 4 destruction of vegetation respiration decay 3 7 Land plants diffusion bicarbonate (HCO 3 ) Ocean coal 6 Soils 5 oil natural gas dead organisms and animal waste
23.3 Global Biogeochemical cycles Carbon cycle Human activities that interfere: Burning of fossil fuels and the destruction of forests are depositing CO 2 to the atmosphere faster than it is being removed CO 2 and other gases (N 2 O and CH 4 ) are being emitted due to human activities These gases are called greenhouse gases because they trap heat that contributes to global warming
23.3 Global Biogeochemical cycles Greenhouse gases and global warming Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. solar radiation solar radiation reflected solar radiation clouds reflected green house gases in atmosphere reradiated Greenhouse effect absorbed Solar radiation that passes through the atmosphere warms the Earth s surface. Clouds, which contain water vapor, absorb infrared rays (heat) from the earth s surface and warm the surface by downward reradiation of a portion of these rays. Green house gases, including carbon dioxide and methane, also cause the atmosphere to absorb and reradiate infrared rays toward the surface of the Earth. As the concentration of green house gases increases, the temperature of the Earth is expected to increase also.
23.3 Global Biogeochemical cycles Nitrogen cycle 78% of the atmosphere is nitrogen gas but it is not in a usable form by plants Nitrogen-fixing bacteria convert nitrogen gas to ammonium that can be used by plants Nitrifying bacteria convert ammonium to nitrate Bacteria convert nitrate back to nitrogen gas through a process called dentrification
Fig. 23.12 23.3 Global Biogeochemical cycles Nitrogen cycle Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. N 2 in Atmosphere N 2 fixation 1 2 7 8 1 nitrogen-fixing bacteria in nodules And soil 8 human activities runoff N 2 fixation denitrification plants dead organisms and animal waste 2 nitrification denitrifying bacteria decomposers 6 NO 3 3 NH 4 + Biotic Community denitrification 7 cyanobacteria NH 4 + Biotic Community phytoplankton nitrifying bacteria 4 NO 2 NO 2 decomposers 5 denitrifying bacteria
23.3 Global Biogeochemical cycles Nitrogen cycle Human activities interfere: We add nitrogen fertilizers that run off into lakes and streams that cause major fish kills by eutrophication Burning of fossil fuels - puts nitrogen oxides and sulfur dioxide into the atmosphere where they combine with water vapor to form acids that return to earth as acid deposition - Result in nitrogen oxides and hydrocarbons that react with one another to produce smog
23.3 Global Biogeochemical cycles Nitrogen cycle
23.3 Global Biogeochemical cycles Phosphorus cycle Phosphate ions become available to living organisms by the slow weathering of rocks Phosphate is a limiting nutrient in ecosystems minable rock geologic uplift Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 animals and animal wastes phosphate mining plants 8 Biotic Community 3 weathering 2 phosphate in soil 8 fertilizer runoff 6 8 sewage treatment plants phosphate in solution biota 5 1 decomposers detritus 7 sediments
23.3 Global Biogeochemical cycles Phosphorus cycle Human activities interfere: Runoff of phosphate due to fertilizer and discharge from sewage treatment plants results in eutrophication Sources of pollution: - Point source specific sources - Nonpoint sources runoff from land
23.3 Global Biogeochemical cycles Sources of pollution Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Oxygen-demanding waste Sources of Water Pollution Leading to Cultural Eutrophication Biodegradable organic compounds (e.g., sewage, wastes from food-processing plants, paper mills, and tanneries) Plant nutrients Sediments Thermal discharges Nitrates and phosphates from detergents, fertilizers, and sewage treatment plants Enriched soil in water due to soil erosion Heated water from power plants Health Hazards Disease-causing agents Bacteria and viruses from sewage and barnyard waste (causing, for example, cholera, food poisoning, and hepatitis) Synthetic organic compounds Inorganic chemicals and minerals Radiation Pesticides, industrial chemicals (e.g., PCBs) Acids from mines and air pollution; dissolved salts; heavy metals (e.g., mercury) from industry Radioactive substances from nuclear power plants, medical and research facilities acidic water from mines sediments city crop dusting biomedical wastes industrial wastes barnyard wastes suburban development sewage treatment plant fertilizer runoff oil pollution nuclear reactor
23.3 Global Biogeochemical cycles Science focus: ozone shield depletion Ozone shield a layer of ozone in the stratosphere that absorbs UV rays preventing them from reaching the earth Causes of depletion: Chlorine atoms primarily from chlorofluorocarbons(cfcs) Freon used as a coolant Cleaning agents Agents used to make Styrofoam Concerns about loss of ozone: Increases mutations leading to skin cancer Adversely affects the immune system Impairs crop and tree growth Can kill off algae and krill that sustain oceanic life
23.3 Global Biogeochemical cycles Science focus: ozone shield depletion Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ozone (Dobson Units) 110 220 330 440 550 Courtesy NASA