Environmental Problems, Their Causes, and Sustainability 1

According to scientists, we urgently need more researchon how the world’s aquatic systems work. Withsuch information we will have a clearer picture of theimpacts of our activities on the earth’s aquatic biodiversityand how we can reduce these impacts.All at last returns to the sea—to Oceanus, the ocean river,like the ever-flowing stream of time, the beginning andthe end.RACHEL CARSONCRITICAL THINKING1. List a limiting factor for each of the following: (a) thesurface layer of a tropical lake, (b) the surface layer of theopen sea, (c) an alpine stream, (d) a large, muddy river,(e) the bottom of a deep lake.2. Why do terrestrial organisms evolve tolerances tobroader temperature ranges than aquatic organisms do?3. Why do aquatic plants such as phytoplankton tend tobe very small, whereas most terrestrial plants such astrees tend to be larger and have more specialized structuressuch as stems and leaves for growth? Why aresome aquatic animals, especially marine mammals suchas whales, extremely large compared with terrestrialanimals?4. How would you respond to someone who proposesthat we use the deep portions of the world’s oceans todeposit our radioactive and other hazardous wastes becausethe deep oceans are vast and are located far awayfrom human habitats? Give reasons for your response.5. Someone tries to sell you several brightly coloredpieces of dry coral. Explain in biological terms why thistransaction is probably fraudulent.6. Developers want to drain a large area of inland wetlandsin your community and build a large housing development.List (a) the main arguments the developerswould use to support this project and (b) the main argumentsecologists would use in opposing this project. Ifyou were an elected city official, would you vote for oragainst this project? Can you come up with a compromiseplan?7. You are a defense attorney arguing in court for sparingan undeveloped old-growth tropical rain forest and acoral reef from severe degradation or destruction by development.Write your closing statement for the defenseof each of these ecosystems. If the judge decides you cansave only one of the ecosystems, which one would youchoose, and why?8. Congratulations! You are in charge of the world. Whatare the three most important features of your plan to helpsustain the earth’s aquatic biodiversity?PROJECTS1. Search for information about mangrove trees, usingthe Internet and library. Are the different species of mangrovetrees closely related? What characteristics do theyhave in common? What characteristics do they have thatmake them a good place for fish to breed?2. If possible, visit a nearby lake or reservoir. Would youclassify it as oligotrophic, mesotrophic, or eutrophic?What are the primary factors contributing to its nutrientenrichment? Which of these factors are related to humanactivities?3. Examine a topographic map for the area around astream or lake near where you live to define the watershedfor the stream. What human activities occur in thewatershed? What influence, if any, do you expect theseactivities to have on the ecology of the stream or lake?4. Use the library or the Internet to find bibliographic informationabout Loren Eisley and Rachel Carson, whosequotes appear at the beginning and end of this chapter.5. Make a concept map of this chapter’s major ideas, usingthe section heads, subheads. and key terms (in boldface).Look on the website for this book for informationabout making concept maps.LEARNING ONLINEThe website for this book contains study aids and manyideas for further reading and research. They include achapter summary, review questions for the entire chapter,flash cards for key terms and concepts, a multiple-choicepractice quiz, interesting Internet sites, references, and aguide for accessing thousands of InfoTrac ® College Editionarticles. Log on tohttp://biology.brookscole.com/miller14Then click on the Chapter-by-Chapter area, choose Chapter7, and select a learning resource.142 CHAPTER 7 Aquatic Biodiversity