1. CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry Cain Wasserman Minorsky Jackson Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 42 Ecosystems and Energy

2. © 2014 Pearson Education, Inc. Overview: Cool Ecosystem  An ecosystem consists of all the organisms living in a community, as well as the abiotic factors with which they interact  An example is the unusual community of organisms, including chemoautotrophic bacteria, living below a glacier in Antarctica  identify the abiotic and biotic factor in this example  what do you think chemoautorophic bacteria might mean?

3. © 2014 Pearson Education, Inc. Concept 42.1: Physical laws govern energy flow and chemical cycling in ecosystems  Ecologists study the transformations of energy and matter within ecosystems

4. © 2014 Pearson Education, Inc. How does the flow of energy and material compare in an environment?

5. © 2014 Pearson Education, Inc.  Energy flows through ecosystems, whereas matter cycles within them

6. © 2014 Pearson Education, Inc. If energy is not being recycled, what is happening to it as it flows through the system?

7. © 2014 Pearson Education, Inc. Conservation of Energy  Laws of physics and chemistry apply to ecosystems, particularly energy flow  The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed  Energy enters an ecosystem as solar radiation, is transformed into chemical energy by photosynthetic organisms, and is dissipated as heat

8. © 2014 Pearson Education, Inc.  The second law of thermodynamics states that every exchange of energy increases the entropy of the universe  what does entropy mean?  In an ecosystem, energy conversions are not completely efficient, and some energy is always lost as heat  what implications does this have?

9. © 2014 Pearson Education, Inc. Why are materials cycled through an ecosystem?

10. © 2014 Pearson Education, Inc. Conservation of Mass  The law of conservation of mass states that matter cannot be created or destroyed  Chemical elements are continually recycled within ecosystems

11. © 2014 Pearson Education, Inc. Draw a model that would describe the flow of energy through an ecosystem.

12. © 2014 Pearson Education, Inc. Energy, Mass, and Trophic Levels  Autotrophs build molecules themselves using photosynthesis or chemosynthesis as an energy source  Heterotrophs depend on the biosynthetic output of other organisms

13. © 2014 Pearson Education, Inc.  Determine how energy and nutrients would pass with the following organisms present:  Tertiary consumers, primary producers, primary consumers, secondary consumers  Which ones are the autotrophs? Heterotrophs?  Which one is the herbivore? Carnivore?

14. © 2014 Pearson Education, Inc.  Detritivores, or decomposers, are consumers that derive their energy from detritus, nonliving organic matter  what are examples of decomposers?  Decomposition connects all trophic levels; detritivores are fed upon by secondary and tertiary consumers  what would happen if the decomposers in an ecosystem went extinct?

15. © 2014 Pearson Education, Inc. Figure 42.3

16. © 2014 Pearson Education, Inc. Typically, we draw the model as a triangular shape to represent the flow of energy; however we could just as easily represent it as a web of interactions (energy and nutrients).

17. © 2014 Pearson Education, Inc. Figure 42.4 Sun Heat Primary producers Primary consumers Detritus Secondary and tertiary consumers Microorganisms and other detritivores Key Chemical cycling Energy flow

18. © 2014 Pearson Education, Inc. How is the energy from light quantified, in terms of output in the form of organic matter?

19. © 2014 Pearson Education, Inc. Concept 42.2: Energy and other limiting factors control primary production in ecosystems  In most ecosystems, primary production is the amount of light energy converted to chemical energy by autotrophs during a given time period  what process are we referring to?  In a few ecosystems, chemoautotrophs are the primary producers

20. © 2014 Pearson Education, Inc. Ecosystem Energy Budgets  The extent of photosynthetic production sets the spending limit for an ecosystem’s energy budget  what is the equation for photosynthesis?  what would be the limiting reactants in this process?

21. © 2014 Pearson Education, Inc. The Global Energy Budget  The amount of solar radiation reaching Earth’s surface limits the photosynthetic output of ecosystems  Only a small fraction of solar energy actually strikes photosynthetic organisms, and even less is of a usable wavelength  what part of the biosphere would receive the most amount of solar energy? The least?

22. © 2014 Pearson Education, Inc. Gross and Net Production  Total primary production is known as the ecosystem’s gross primary production (GPP)  GPP is measured as the conversion of chemical energy from photosynthesis per unit time  when might part of the GPP get lost?

23. © 2014 Pearson Education, Inc.  Net primary production (NPP) is GPP minus energy used by primary producers for “autotrophic respiration” (R a )  NPP is expressed as  Energy per unit area per unit time (J/m 2  yr), or  Biomass added per unit area per unit time (g/m 2  yr) NPP = GPP − R a

24. © 2014 Pearson Education, Inc.  NPP is the amount of new biomass added in a given time period  what is available to consumers, GPP or NPP? Explain.  Ecosystems vary greatly in NPP and contribution to the total NPP on Earth  which biomes do you think would produce the most amount of NPP? Why?

25. © 2014 Pearson Education, Inc. Figure 42.5 Technique Snow Clouds Vegetation Soil Liquid water Percent reflectance Wavelength (nm) VisibleNear-infrared 4006008001,0001,200 0 20 40 60 80

26. © 2014 Pearson Education, Inc. Figure 42.6 Net primary production (kg carbon/m 2 yr) 3 2 1 0

27. © 2014 Pearson Education, Inc.  Tropical rain forests, estuaries, and coral reefs are among the most productive ecosystems per unit area  However, Marine biomes actually contribute the majority of NPP.  how is this possible? Video: Oscillatoria

28. © 2014 Pearson Education, Inc.  Net ecosystem production (NEP) is a measure of the total biomass accumulation during a given period  NEP is gross primary production minus the total respiration of all organisms (producers and consumers) in an ecosystem (R T ) NEP = GPP − R T

29. © 2014 Pearson Education, Inc. What factors would affect primary production in aquatic ecosystems (where most of the NPP is)?

30. © 2014 Pearson Education, Inc. Primary Production in Aquatic Ecosystems  In marine and freshwater ecosystems, both light and nutrients control primary production

31. © 2014 Pearson Education, Inc. Light Limitation  Depth of light penetration affects primary production of an ocean or lake  would production be greater in the photic or aphotic region? Explain.  About half the solar radiation is absorbed in the first 15 m of water, and only 5–10% reaches a depth of 75 m  based on this information, in what region would most photosynthetic organism be found?  where would GPP be greatest?

32. © 2014 Pearson Education, Inc. Nutrient Limitation  nutrients limit primary production in geographic regions of the ocean and in lakes  A limiting nutrient is the element that must be added for production to increase in an area  what are important nutrients needed for plants?

33. © 2014 Pearson Education, Inc. Figure 42.7 Results Ammonium enriched Phosphate enriched Unenriched control Collection site ABCDEFG 0 6 12 18 24 30 Phytoplankton density (millions of cells per mL)

34. © 2014 Pearson Education, Inc. Table 42.1

35. © 2014 Pearson Education, Inc.  Upwelling of nutrient-rich waters in parts of the oceans contributes to regions of high primary production  The addition of large amounts of nutrients to lakes has a wide range of ecological impacts  what happens to lakes that have undergone eutrophication?

36. © 2014 Pearson Education, Inc. Primary Production in Terrestrial Ecosystems  In terrestrial ecosystems, temperature and moisture affect primary production on a large scale  what do you think happens to primary production as moisture increases? Explain your reasoning.

37. © 2014 Pearson Education, Inc. Figure 42.8 1,400 1,200 1,000 800 600 400 200 020200406080100120140160180 Mean annual precipitation (cm) Net annual primary production (above ground, dry g/m 2 yr)

38. © 2014 Pearson Education, Inc.  On a more local scale, a soil nutrient is often the limiting factor in primary production  In terrestrial ecosystems, nitrogen is the most common limiting nutrient  Phosphorus can also be a limiting nutrient, especially in older soils Nutrient Limitations and Adaptations That Reduce Them

39. © 2014 Pearson Education, Inc. In ecosystems where there is an element, like Nitrogen, that is a limiting factor, what relationships and/or adaptations would we expect to observe to mediate this problem?

40. © 2014 Pearson Education, Inc.  Various adaptations help plants access limiting nutrients from soil  Mutualism:  Nitrogen fixing bacteria  Fungi to absorb phosphorous  Roots have root hairs that increase surface area  Many plants release enzymes that increase the availability of limiting nutrients

41. © 2014 Pearson Education, Inc. How would you interpret this figure? Plant material eaten by caterpillar Cellular respiration Growth (new biomass; secondary production) Not assimilated Feces 100 J 200 J 33 J 67 J Assimilated

42. © 2014 Pearson Education, Inc. Concept 42.3: Energy transfer between trophic levels is typically only 10% efficient  Secondary production of an ecosystem is the amount of chemical energy in food converted to new biomass during a given period of time  Define biomass.

43. © 2014 Pearson Education, Inc.  Birds and mammals have efficiencies in the range of 1  3% because of the high cost of endothermy  what is endothermy?  Insects and microorganisms have efficiencies of 40% or more

44. © 2014 Pearson Education, Inc. Trophic Efficiency and Ecological Pyramids  Trophic efficiency is the percentage of production transferred from one trophic level to the next  approximately, how much energy gets transferred?  where does the energy get lost?  in a food chain, which organisms get the least energy- tertiary consumers or primary consumers? Explain.

45. © 2014 Pearson Education, Inc. Figure 42.10 Tertiary consumers Secondary consumers Primary consumers Primary producers 10 J 100 J 1,000 J 10,000 J 1,000,000 J of sunlight

46. © 2014 Pearson Education, Inc.  Approximately 0.1% of chemical energy fixed by photosynthesis reaches a tertiary consumer  A pyramid of net production represents the loss of energy with each transfer in a food chain

47. © 2014 Pearson Education, Inc. Figure 42.11 Trophic level Tertiary consumers Secondary consumers Primary consumers Primary producers (a) Most ecosystems (data from a Florida bog) (b) Some aquatic ecosystems (data from the English Channel) Trophic level Dry mass (g/m 2 ) Dry mass (g/m 2 ) 1.5 11 37 809 4 21Primary consumers (zooplankton) Primary producers (phytoplankton)

48. © 2014 Pearson Education, Inc. Why is the biomass pyramid inverted in the aquatic ecosystem?

49. © 2014 Pearson Education, Inc.  Certain aquatic ecosystems have inverted biomass pyramids: producers (phytoplankton) are consumed so quickly that they are outweighed by primary consumers

50. © 2014 Pearson Education, Inc.  Dynamics of energy flow in ecosystems have important implications for the human population  Based on this information- which is more efficient in capturing energy derived from a photosynthetic process- eating plants or animals?

51. © 2014 Pearson Education, Inc. C, H, N, O, P, S Why do these elements need to be recycled through the ecosystem?

52. © 2014 Pearson Education, Inc. Concept 42.4: Biological and geochemical processes cycle nutrients and water in ecosystems  Life depends on recycling chemical elements  Decomposers (detritivores) play a key role in the general pattern of chemical cycling

53. © 2014 Pearson Education, Inc. Decomposition and Nutrient Cycling Rates  Rates at which nutrients cycle in different ecosystems vary greatly, mostly as a result of differing rates of decomposition

54. © 2014 Pearson Education, Inc. Describe some abiotic factors that may affect rates of decomposition.

55. © 2014 Pearson Education, Inc. Decomposition and Nutrient Cycling Rates  Rates at which nutrients cycle in different ecosystems vary greatly, mostly as a result of differing rates of decomposition  The rate of decomposition is controlled by temperature, moisture, and nutrient availability

56. © 2014 Pearson Education, Inc. Interpret this figure. Experiment Ecosystem type Arctic Subarctic Boreal Temperate Grassland Mountain A Results G M T S U N H,I L B,C E,F K D P O J R Q P U T R Q S O K J N M L I H G E B A C D F 80 70 60 50 40 30 20 10 0 −15−10−5−5051015 Mean annual temperature (°C) Percent of mass lost

57. © 2014 Pearson Education, Inc.  Rapid decomposition results in relatively low levels of nutrients in the soil  For example, in a tropical rain forest, material decomposes rapidly, and most nutrients are tied up in trees and other living organisms  Cold and wet ecosystems store large amounts of undecomposed organic matter, as decomposition rates are low  Decomposition is slow in anaerobic muds

58. © 2014 Pearson Education, Inc. Biogeochemical Cycles  Nutrient cycles in ecosystems involve biotic and abiotic components and are often called biogeochemical cycles **************************************************************  Gaseous carbon, oxygen, sulfur, and nitrogen occur in the atmosphere and cycle globally  Less mobile elements include phosphorus, potassium, and calcium  These elements cycle locally in terrestrial systems but more broadly when dissolved in aquatic systems

59. © 2014 Pearson Education, Inc.  Each step in a chemical cycle can be driven by biological or purely physical processes

60. © 2014 Pearson Education, Inc. Figure 42.13a Movement over land by wind Precipitation over land Percolation through soil Evaporation from ocean Evapotranspiration from land Precipitation over ocean Runoff and groundwater The water cycle

61. © 2014 Pearson Education, Inc. Figure 42.13b Consumers Decomposition Photosynthesis Cellular respiration Photo- synthesis Phyto- plankton CO 2 in atmosphere Burning of fossil fuels and wood The carbon cycle

62. © 2014 Pearson Education, Inc. Figure 42.13ca Fixation Denitrification Runoff N fertilizers Reactive N gases Industrial fixation N 2 in atmosphere NO 3 − NH 4  Dissolved organic N NO 3 − Aquatic cycling Decomposition and sedimentation The nitrogen cycle

63. © 2014 Pearson Education, Inc. Figure 42.13cb Terrestrial cycling Fixation in root nodules Decom- position N2N2 NO 3 − NH 4  Ammoni- fication Assimilation Denitri- fication Uptake of amino acids Nitrification The nitrogen cycle

64. © 2014 Pearson Education, Inc. Figure 42.13d Wind-blown dust Geologic uplift Weathering of rocks Decomposition PlanktonDissolved Uptake Leaching Decomposition Consumption Runoff PO 4 3− Plant uptake of PO 4 3− Sedimentation The phosphorus cycle

65. © 2014 Pearson Education, Inc. Case Study: Nutrient Cycling in the Hubbard Brook Experimental Forest  The Hubbard Brook Experimental Forest has been used to study nutrient cycling in a forest ecosystem since 1963  The research team constructed a dam on the site to monitor loss of water and minerals  They found that 60% of the precipitation exits through streams and 40% is lost by evapotranspiration  Most mineral nutrients were conserved in the system

66. © 2014 Pearson Education, Inc. Figure 42.14 Concrete dam and weir (b) Clear-cut watershed (a) (c) Nitrate in runoff from watersheds Deforested Control Completion of tree cutting 1968196719661965 0 1 2 3 4 20 40 60 80 Nitrate concentration in runoff (mg/L)

67. © 2014 Pearson Education, Inc.  In one experiment, the trees in one valley were cut down, and the valley was sprayed with herbicides

68. © 2014 Pearson Education, Inc.  Net losses of water were 30  40% greater in the deforested site than in the undisturbed (control) site  Nutrient loss was also much greater in the deforested site compared with the undisturbed site  For example, nitrate levels increased 60 times in the outflow of the deforested site  These results showed that the amount of nutrients leaving a forest ecosystem is controlled mainly by plants

69. © 2014 Pearson Education, Inc. Excluding ecological succession, describe other ways ecosystems can be repaired.

70. © 2014 Pearson Education, Inc. Concept 42.5: Restoration ecologists help return degraded ecosystems to a more natural state  Given enough time, biological communities can recover from many types of disturbances  Restoration ecology seeks to initiate or speed up the recovery of degraded ecosystems  Two key strategies are bioremediation and augmentation of ecosystem processes

71. © 2014 Pearson Education, Inc. Figure 42.15 (a) In 1991, before restoration In 2000, near the completion of restoration (b)

72. © 2014 Pearson Education, Inc. Define bioremediation. Provide an example of its use in environmental clean-ups.

73. © 2014 Pearson Education, Inc. Bioremediation  Bioremediation is the use of organisms to detoxify ecosystems  The organisms most often used are prokaryotes, fungi, or plants  These organisms can take up, and sometimes metabolize, toxic molecules  For example, the bacterium Shewanella oneidensis can metabolize uranium and other elements to insoluble forms that are less likely to leach into streams and groundwater

74. © 2014 Pearson Education, Inc. Biological Augmentation  Biological augmentation uses organisms to add essential materials to a degraded ecosystem  For example, nitrogen-fixing plants can increase the available nitrogen in soil  For example, adding mycorrhizal fungi can help plants to access nutrients from soil

75. © 2014 Pearson Education, Inc. Restoration Projects Worldwide  The newness and complexity of restoration ecology require that ecologists consider alternative solutions and adjust approaches based on experience.