CH-7-8 Climate and Biodiversity – Living in the Environment: Principles, Connections, and Solutions : Book Guide

This Document Contains Chapters 7 to 8 Chapter 7 Climate and Biodiversity Summary 1. Key factors that determine the earth’s weather are short-term atmospheric conditions such as temperature, pressure, moisture content, sunshine, cloud cover, precipitation, wind direction, and wind speed. 2. Climate is a region’s long-term atmospheric conditions over decades. The two main factors in determining climate are average temperature and average precipitation. 3. The average climate—annual precipitation and temperature—determines terrestrial regions with characteristic types of natural ecological communities. According to these two factors, biomes form. 4. The major types of desert biomes are hot, temperate, and cold. Human activities have created large desert cities, destroyed soil through urban development and off-road vehicles, salinized the soil through irrigation, depleted underground water supplies, disturbed land and polluted, stored toxic and radioactive wastes, and located arrays of solar cells and solar collectors. 5. The three major types of grasslands are tropical or savannas, temperate grasslands, and polar grassland/tundra. The savannas have been destroyed by grazing cattle, which destroy vegetation and kills grass through fecal droppings. The temperate grasslands have been used to grow crops and graze animals. As a result, the grasslands have disappeared. The arctic tundra has been compromised by oil drilling, mines, and military bases. 6. The three main types of forest biomes are tropical, temperate, and polar/boreal. Human activities have destroyed much of the native trees; grazing has compromised the vegetation and eliminated food sources for native animals. And the deforestation has changed the tropical forest’s ecosystem, leading to death of plants and animals. The temperate forest has a fewer number of broadleaf trees and rich forest soil; but fires, logging, and hunting have undermined this type of forest. The evergreen firs of the polar forest support a variety of wildlife. But oil drilling and oil spills have compromised the water, the wildlife, and the vegetation in the arctic. 7. Mountain and arctic biomes play important ecological roles; they help regulate climate and effect sea levels. Mountain biome degradation arises from timber and mining extraction, from hydroelectric dams and reservoirs, from air pollution, increased tourism, and radiation from ozone depletion. Key Questions and Concepts 7-1 What factors influence climate? CORE CASE STUDY: The location of biomes is determined by climate. There are three major types of climate: tropical, polar and temperate. These determine the three major biomes: forests, grasslands and deserts. When climate changes, there is a concomitant shift in biome location. A. Weather is a local area’s short-term physical conditions such as temperature and precipitation. Average temperature and average precipitation are the two major factors that determine climate of a region, together with the related factors of latitude and elevation. 1. Climate refers to long term general patters of atmospheric conditions. B. Global air circulation is affected by the uneven heating of the earth’s surface by solar energy, seasonal changes in temperature and precipitation, rotation of the earth on its axis, and the properties of air, water, and land. 1. Uneven heating of earth’s surface: the equator is heated more than the poles. 2. Rotation of the earth on its axis results in the earth moving faster beneath air masses at the equator and slower at the poles. Belts of prevailing winds are the result. 3. Properties of air, water, and land affect global air circulation. Water evaporation sets up cyclical convection cells. These occur both vertically and from place to place in the troposphere. The result is an irregular distribution of climates and patterns of vegetation from pole to pole. C. Ocean currents influence climate by distributing heat from place to place and mixing and distributing nutrients. 1. Differences in water density and heat create ocean currents that are warm/cold. 2. Currents redistribute absorbed solar heat from one place to another, influence vegetation and climate near coastal regions. 3. Currents also help mix ocean waters to distribute nutrients and dissolved oxygen needed for aquatic organisms. 4. Winds and the earth’s rotation drive the currents. D. Water vapor, carbon dioxide, and other gases influence climate by warming the lower atmosphere and the earth’s surface. 1. These gasses (water vapor, carbon dioxide, methane, and nitrous oxide) are known as greenhouse gasses. They allow mostly visible light, some infrared radiation, and ultraviolet radiation to pass through the troposphere. This natural warming is the greenhouse effect. E. Interactions between land and oceans and disruptions of airflows by mountains and cities affect local climates. Various topographic features can create local and regional microclimates. 1. One example of this is the rain shadow effect. 2. Bricks, asphalt, and other building materials create distinct microclimates in cities. 7-2 How does climate affect the nature and location of biomes? A. Different climates lead to different communities of organisms, especially vegetation. Differences in average temperature and precipitation due to global air and water circulation lead to differences in climate. 1. Average annual precipitation, temperature, and soil type are the most important factors in producing tropical, temperate, or polar deserts, grasslands, and forests. 2. Biomes are actually a mosaic of different biological communities. 3. Climate and vegetation vary with latitude and elevation of an area. B. Deserts have little precipitation and little vegetation and are found in tropical, temperate, and polar regions. 1. Tropical deserts are hot and dry most of the year with few plants, rocks, and sand. 2. Temperate deserts have high daytime temperatures in summer and low temperatures in winter, with more rain than in tropical deserts. 3. Cold deserts have cold winters and warm summers, with low rainfall. SCIENCE FOCUS: Plants and animals have numerous adaptations to the harsh conditions in desert environments. These tend to revolve around avoiding heat, and absorbing or retaining the maximum amount of water. C. Grasslands have enough precipitation to support grasses but not enough to support large stands of trees. The three main types of grasslands are tropical, temperate, and polar (tundra). 1. Savannas are tropical grasslands with scattered trees and enormous herds of hoofed animals. a. Large herds of grazing and browsing animals feed here. 2. Temperate grasslands with cold winters and hot, dry summers have deep and fertile soils that make them widely used for growing crops and grazing cattle. a. Organic matter accumulates, producing fertile soil, as aboveground plant parts die each year. b. North American grasslands are tall-grass prairies and short-grass prairies. 3. Polar grasslands are covered with ice and snow except during a brief summer. a. Under the snow there is a thick, spongy mat of low-growing vegetation (grasses, mosses, dwarf woody shrubs). b. Permafrost is a permanently frozen layer of soil when water freezes. c. Global warming is causing some parts of the permafrost in parts of Alaska to melt. d. Another type of tundra, alpine tundra, occurs above tree line, but below permanent snow line. This area gets more sunlight than arctic tundra and has no permafrost. D. Chaparral has a moderate climate but its dense thickets of spiny shrubs are subject to periodic fire. Chaparral, or temperate shrubland, is found in coastal areas that border deserts. 1. The winter rainy season is longer than in desert; fog during spring/fall reduces evaporation. 2. Low-growing evergreen shrubs with occasional trees is the vegetation type. 3. Fires move swiftly when started in these areas. Chaparral is adapted to occasional fires. 4. Floods/mudslides occur after fires at times. E. Forests have enough precipitation to support stands of trees and are found in tropical, temperate, and polar regions. There are three main types of forest—tropical, temperate, and boreal (polar). 1. Tropical rain forests have heavy rainfall on most days and a rich diversity of species occupying a variety of specialized niches in distinct layers. Tropical rain forests are near the equator and have hot, humid conditions. a. Dominant plants are broadleaf evergreens with shallow roots. b. A dense canopy blocks most sunlight from reaching lower levels. c. Vines often drape individual trees. d. Tropical forests cover about 2% of the land surface, but are habitat for about half the terrestrial species of earth. e. Very little litter is on the forest floor because of rapid recycling of dead materials. f. So far, at least half of these forests have been destroyed or disturbed by human activities. 2. Temperate deciduous forests grow in areas with moderate average temperatures, abundant rainfall, and long, warm summers. a. Broadleaf, deciduous trees dominate this biome. Leaves drop in fall, trees become dormant, and new leaves grow in spring. b. More sunlight penetrates the canopy so there is richer diversity of ground level plant life. c. On a worldwide basis, this biome has been disturbed by human activity more than any other terrestrial biome as a result of establishing settlements, industrialization, and urbanization. 3. Evergreen coniferous forests or boreal forests are located in areas just south of arctic tundra around the northern sub-arctic regions of the earth. These forests consist mostly of cone-bearing evergreen trees that keep their needles year-round to help the trees survive long, cold winters. a. Long, dry, extremely cold winters are the norm. Summers are short. b. Dominant trees are coniferous (cone-bearing) spruce, hemlock, fir, cedar, and pine. c. There is low plant diversity. 4. Coastal areas support huge cone-bearing evergreen trees such as redwoods and Douglas fir in a cool and moist environment. Coastal coniferous forests or temperate rain forests are located along the western coast of Canada to northern California. Cool temperatures, abundant rain, and dense fog are the norm. 5. Mountains are high-elevation forested islands of biodiversity and often have snow-covered peaks that reflect solar radiation and gradually release water to lower-elevation streams and ecosystems. Mountains are places with dramatic changes in altitude, climate, soil, and vegetation within very short distances. a. Mountains have important ecological roles such as habitats for endemic species, biodiversity, and sanctuaries for animal species driven from other habitats. b. Mountains play a major role in the hydrologic cycle. 7-3 How have we affected the world’s terrestrial ecosystems? A. Human activities have damaged or disturbed to some extent about 62% of the world’s terrestrial ecosystems. B. Humans have had a number of specific harmful effects on the world’s deserts, grassland, forests, and mountains. Teaching Tips Large Lecture Courses: As a group, first brainstorm a list of the major ecosystems in the local area. Some places are surprisingly diverse, when taking into account the places one might drive to in a day. For each of these, ask the students to propose in what way the climate determines where that ecosystem is found. Focus particular attention on rain shadows and the similarity between latitude and elevation. Smaller Lecture Courses: Have the class as a whole brainstorm a list of the major ecosystems in the local area. Next, break the class into small groups, assigning each a particular ecosystem or biome. Have them suggest what human activities are causing the most damage or disruption to that ecosystem. After allowing time to do so, compile these lists on the board and determine the extent to which there is overlap between biomes. Key Terms biomes climate greenhouse effect greenhouse gases ocean currents permafrost rain shadow effect weather Term Paper Research Topics 1. Weather and climate: greenhouse effect; microclimates. 2. Plant and animal adaptations to different biomes: desert plants and animals; plants and animals of the tundra; mountain microclimates and vertically zoned vegetation; organisms of the Amazon. 3. Fragile ecosystems: deserts; tropical forests; tundra. 4. Should Alaska be opened up to more oil drilling? Debate the pros and cons of this issue. 5. Global: the Montreal Protocol; Kyoto Protocol. Discussion Topics 1. How are mountain ecosystems like "islands of biodiversity"? What other island-like habitats are there? Answer: Mountain ecosystems are like "islands of biodiversity" because their isolated and varying altitudes create unique habitats that support diverse plant and animal species, similar to how islands harbor distinct species due to isolation. Other island-like habitats include coral reefs, which offer diverse marine environments, and wetlands, which provide specialized niches for various organisms. 2. Why are rainforests more diverse than other forests? Answer: Rainforests are more diverse due to their consistently warm temperatures, high humidity, and abundant rainfall, which create ideal conditions for a wide range of species. Their complex structure, with multiple canopy layers, provides numerous ecological niches and promotes high levels of species richness. 3. What would happen if ocean currents stopped redistributing heat? How could this situation arise? Answer: If ocean currents stopped redistributing heat, it would lead to severe climate changes, such as more extreme temperatures and disrupted weather patterns. This situation could arise from disruptions to ocean circulation due to factors like melting polar ice, changes in salinity, or large-scale volcanic eruptions. 4. Is the greenhouse effect the same as global warming? How do these two concepts differ? Answer: The greenhouse effect is a natural process where certain gases trap heat in the Earth's atmosphere, keeping the planet warm. Global warming refers to the recent trend of increased average global temperatures due to human activities that amplify the greenhouse effect, such as increased carbon dioxide emissions. 5. Why are grasslands well-suited for raising crops? Answer: Grasslands are well-suited for raising crops due to their fertile soils, flat terrain, and moderate rainfall. These conditions support large-scale agriculture and allow for efficient planting and harvesting of various crops, particularly grains. 6. What are the three most important attributes or ecosystem functions of your local biome? Answer: In a temperate forest biome, three key attributes are: nutrient cycling, where decomposers break down organic matter and recycle nutrients; carbon sequestration, which helps mitigate climate change by absorbing carbon dioxide; and habitat provision, supporting diverse wildlife and plant species. Activities and Projects 1. Arrange a field trip providing opportunities to compare and contrast ecosystems of several different types. Do the boundaries among different kinds of ecosystems tend to be sharply delineated? 2. Ask students to bring to class and share examples of art, music, poetry, and other creative expressions of human thoughts and feelings about earth's climate, deserts, grasslands, forests, and oceans. Lead a class discussion on the subject of how human culture has been shaped to an important degree by the environmental conditions of each major biome. 3. Visit a weather station to see the types of equipment that are used to predict the weather. 4. Invite a climatologist to visit your classroom to describe the climate of your region: past, present, and future. 5. What soil types and significantly different microclimates exist in your locale? As a class project, inventory these elements of diversity and relate them to observable differences in the distribution of vegetation, animal life, agricultural activities, and other phenomena. Attitudes and Values 1. What is blowing in the wind in your community? How does the wind make you feel? Answer: In my community, the wind might carry the scent of blooming flowers, leaves rustling, or even dust from nearby construction. The wind often feels refreshing and invigorating, though it can also bring a sense of restlessness or chill, depending on its intensity. 2. Do you feel that the development of your community is related to the climate of the area? Are there any connections you have experienced? Answer: Yes, the development of my community is closely related to the local climate. For instance, the choice of construction materials and building designs often consider the climate, such as using cooling techniques in hot areas or insulating materials in colder regions. Local climate influences agricultural practices and the types of vegetation that thrive in the area. 3. Are you aware of mountains or bodies of water in your area that affect local climate conditions? Answer: Yes, local mountains or bodies of water can significantly affect climate conditions. Mountains might create rain shadows, affecting precipitation patterns, while bodies of water, like lakes or rivers, can moderate temperatures and influence humidity levels. 4. Do humans have a right to use the atmosphere in any way they wish? Do you see limits to freedom of choice? If so, what determines those limits? Answer: Humans do not have an unlimited right to use the atmosphere, as unrestricted use can lead to pollution and climate change, impacting all living beings. Limits to freedom of choice are determined by ethical considerations, environmental regulations, and the need to protect public health and the global ecosystem. 5. Do you feel that humans have the power to alter Earth's climate? Do you feel that humans can responsibly control their impact on the atmosphere? Answer: Yes, humans have the power to alter Earth's climate through activities such as burning fossil fuels and deforestation. While we can make significant strides in controlling our impact through technology and policy changes, responsible management requires global cooperation and commitment to sustainable practices. Additional Video Resources Amazon: IMAX (1997) An exploration of the Amazonian rainforest from the perspectives of medicine men and ethnobotanists. http://www.amazon.com/Amazon-IMAX-2-Disc-WMVHD-Linda/dp/B00022PYZ2 Baked Alaska (2003) Film looks at the battle over the Arctic National Wildlife Refuge (ANWR) in the context of Alaska's accelerated warming. http://www.bullfrogfilms.com/catalog/ba.html Conserving America: The Wetlands (PBS, 1994) A four-part series on American Conservation of wetlands. Planet Earth Series (Discovery, Channel TV Series) http://dsc.discovery.com/convergence/planet-earth/planet-earth.html Strange Days on Planet Earth (TV Series, National Geographic, 2008) http://www.pbs.org/strangedays/ The Day After Tomorrow (Movie, 2004) A climatologist tries to figure out a way to save the world from abrupt global warming. Too Hot not to Handle (Documentary, HBO, 2006) A look at global warming and what we can do about it. http://www.hbo.com/docs/programs/toohot/index.html NOVA: What's up with the Weather? Main website: http://www.pbs.org/wgbh/warming/ Teachers Guide: http://www.pbs.org/wgbh/nova/teachers/programs/27gw_warming.html Web Resources Introduction to Biomes http://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/intro.html An exploration of the major biomes of the world. Suggested Answers to End of Chapter Review Questions Review Questions 1. Review the Key Questions and Concepts for this chapter on p. 148. Describe how differences in climate lead to formation of tropical, temperate, and polar deserts, grasslands, and forests. Answer: • Differences in climate, mostly from average annual precipitation and temperature, lead to the formation of tropical (hot), temperate (moderate), and polar (cold) deserts, grasslands, and forests. 2. Distinguish between weather and climate. Describe three major factors that determine how air circulates in the lower atmosphere. Describe how the properties of air, water, and land affect global air circulation. Define ocean currents and explain how they, along with global air circulation, support the formation of forests, grasslands, and deserts. Answer: • Weather is a set of physical conditions of the lower atmosphere such as temperature, precipitation, humidity, wind speed, cloud cover, and other factors in a given area over a period of hours or days. • Climate is an area’s general pattern of atmospheric conditions over periods ranging from at least three decades to thousands of years. • Three major factors determine how air circulates in the lower atmosphere: ○ Uneven heating of the earth’s surface by the sun ○ Rotation of the earth on its axis ○ Properties of air, water, and land • Heat from the sun evaporates ocean water and transfers heat from the oceans to the atmosphere, especially near the hot equator. This evaporation of water creates giant cyclical convection cells that circulate air, heat, and moisture both vertically and from place to place in the atmosphere. • The earth’s air circulation patterns, prevailing winds, and configuration of continents and oceans result in giant convection cells in which warm, moist air rises and cools, and cool, dry air sinks. These cells lead to an irregular distribution of climates and deserts, grasslands, and forests. 3. Define and give four examples of a greenhouse gas. What is the greenhouse effect and why is it important to the earth’s life and climate? Answer: • Greenhouse gases include several gases in the atmosphere, including water vapor (H2O), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), which absorb and release heat that warms the atmosphere. • The earth’s surface absorbs solar energy and transforms it to heat, which then rises into the lower atmosphere. Some of this heat escapes into space, but some is absorbed by molecules of greenhouse gases and emitted into the lower atmosphere. This natural warming effect of the troposphere is called the greenhouse effect. • The greenhouse gases and the natural greenhouse effect play an essential role in determining the earth’s average temperatures and its climates. 4. What is the rain shadow effect and how can it lead to the formation of deserts? Why do cities tend to have more haze and smog, higher temperatures, and lower wind speeds than the surrounding countryside? Answer: • The rain shadow effect is a reduction of rainfall and loss of moisture from the landscape on the side of mountains facing away from prevailing surface winds. Warm, moist air in onshore winds loses most of its moisture as rain and snow on the windward slopes of a mountain range. This leads to semi-arid and arid conditions on the leeward side of the mountain range and the land beyond. • Cities have building materials that absorb and hold heat, buildings that block wind flow, and motor vehicles and the climate-control systems of buildings that release large quantities of heat and pollutants, resulting in more haze and smog, higher temperatures, and lower wind speeds than the surrounding countryside. 5. What is a biome? Explain why there are three major types of each of the major biomes (deserts, grasslands, and forests). Describe how climate and vegetation vary with latitude and elevation. Answer: • Biomes are large terrestrial regions, such as forests, deserts, and grasslands, with distinct climates and certain species (especially vegetation) adapted to them. • The three major biomes are determined by the amount of precipitation. • Differences in climate, mostly from average annual precipitation and temperature, lead to the formation of tropical (hot), temperate (moderate), and polar (cold) deserts, grasslands, and forests. • Both climate and vegetation vary with latitude and elevation. If you climb a tall mountain from its base to its summit, you would encounter deciduous forest, coniferous forest, tundra, then mountain ice and snow. 6. Describe how the three major types of deserts differ in their climate and vegetation. How do desert plants and animals survive? Answer: • Tropical deserts are hot and dry most of the year with few plants and a hard, windblown surface strewn with rocks and some sand. • Temperate deserts have high daytime temperatures in summer and low in winter and there is more precipitation than in tropical deserts, with sparse vegetation consisting mostly of widely dispersed, drought-resistant shrubs and cacti or other succulents adapted to the lack of water and temperature variations. • Cold deserts have cold winters and warm or hot summers and low precipitation, with desert plants and animals having adaptations that help them stay cool and get enough water to survive. 7. Describe how the three major types of grasslands differ in their climate and vegetation. What is a savanna? Why have many of the world’s temperate grasslands disappeared? What is permafrost? Distinguish between arctic tundra and alpine tundra. Answer: • Tropical grasslands like the savanna contain widely scattered clumps of trees such as acacia, which are covered with thorns that keep some herbivores away. This biome usually has warm temperatures year-round and alternating dry and wet seasons. • Temperate grassland has winters that can be bitterly cold, summers that are hot and dry, and annual precipitation that is fairly sparse and falls unevenly through the year. Most of the grasses die and decompose each year, and organic matter accumulates to produce a deep, fertile soil. • Cold grasslands, or arctic tundra (Russian for “marshy plain”), lie south of the Arctic polar ice cap. During most of the year, these treeless plains are bitterly cold. Winters are long and dark, and scant precipitation falls mostly as snow. Under the snow, this biome is carpeted with a thick, spongy mat of low-growing plants—primarily grasses, mosses, lichens, and dwarf shrubs. • Many of the world’s natural temperate grasslands have disappeared because their fertile soils are useful for growing crops and grazing cattle. • Permafrost is the underground soil in which captured water stays frozen for more than two consecutive years. • Arctic tundra is found in the northern polar region. Alpine tundra occurs above the limit of tree growth but below the permanent snow line on high mountains. The vegetation is similar to that found in arctic tundra, but it receives more sunlight than arctic vegetation gets. During the brief summer, alpine tundra can be covered with an array of beautiful wildflowers. 8. What are the three major types of forests? Describe how these three types differ in their climate and vegetation. Why is biodiversity so high in tropical rain forests? Why do most soils in tropical rain forests hold few plant nutrients? Describe what happens in temperate deciduous forests in the winter and fall. What are coastal coniferous or temperate rain forests? What important ecological roles do mountains play? Answer: • Tropical rain forests are found near the equator where hot, moisture-laden air rises and dumps its moisture; these lush forests have year-round, uniformly warm temperatures, high humidity, and heavy rainfall almost daily. • Temperate deciduous forests grow in areas with moderate average temperatures that change significantly with the season, supporting species such as oak, hickory, maple, poplar, and beech. • Cold forests have intense cold and drought in winter when snow blankets the ground, and trees that take advantage of the brief summers because they need not take time to grow new needles. • Tropical rain forest life forms occupy a variety of specialized niches in distinct layers. Stratification of specialized plant and animal niches in a tropical rain forest enables the coexistence of a great variety of species (high species diversity). • Dropped leaves, fallen trees, and dead animals decompose quickly because of the warm, moist conditions and the hordes of decomposers. This rapid recycling of scarce soil nutrients explains why there is so little plant litter on the ground. Instead of being stored in the soil, about 90% of plant nutrients released by decomposition are quickly taken up and stored by trees, vines, and other plants. • The trees found in deciduous forests survive cold winters by dropping their leaves in the fall and becoming dormant through the winter. • Coastal coniferous forests or temperate rain forests are found in scattered coastal temperate areas that have ample rainfall or moisture from dense ocean fogs. Dense stands of large conifers once dominated undisturbed areas of this biome along the coast of North America, from Canada to northern California. • Mountains help to regulate the earth’s climate. Mountaintops covered with ice and snow reflect some solar radiation back into space, which helps to cool the earth and offset global warming. 9. Describe how human activities have affected the world’s deserts, grasslands, forests, and mountains. Answer: • Ways that we have affected deserts include: large desert cities, soil destruction by off road vehicles, soil salinization from irrigation, depletion of groundwater, land disturbance, and pollution from mineral extraction. • Ways that we have affected grasslands include: conversion to cropland, release of CO2 to atmosphere from burning grassland, overgrazing by livestock, and oil production and off-road vehicles in arctic tundra. • Ways that we have affected forests include: clearing for agriculture, livestock grazing, timber, urban development, conversion of diverse forests to tree plantations, damage from off-road vehicles, and pollution of forest streams. • Ways that we have affected mountains include: agriculture, timber extraction, mineral extraction, hydroelectric dams and reservoirs, increasing tourism, urban air pollution, increased ultraviolet radiation from ozone depletion, and soil damage from off-road vehicles. 10. What are this chapter’s three big ideas? Describe the connections between the climates, terrestrial systems, and the three principles of sustainability (see back cover). Answer: • The climate is driven by solar power and determines what the biodiversity in any terrestrial system will be. Nutrients are cycled throughout these systems and the rate of cycling is generally determined by the climate. Critical Thinking The following are examples of the material that should be contained in possible student answers to the end of chapter Critical Thinking questions. They represent only a summary overview and serve to highlight the core concepts that are addressed in the text. It should be anticipated that the students will provide more in-depth and detailed responses to the questions depending on an individual instructor’s stated expectations. 1. What would be likely to happen to the earth’s climate (a) if most of the world’s oceans disappeared and (b) if most of the world’s land disappeared? Answer: Heat from the oceans affects atmospheric circulation and oceans play a large role in the hydrologic cycle. Without the oceans, the climate would be altered on a global scale. Land masses determine in large part how much of the sun’s energy is absorbed or re-radiated, depending upon the predominant vegetation. Similarly, topographic variations create local and regional climatic conditions. 2. Describe the role of temperature and precipitation in determining what parts of the earth’s land are covered with: (a) desert, (b) arctic tundra, (c) temperate grasslands, (d) tropical rainforests, and (e) temperate deciduous forest. Answer: (a) Deserts are limited by precipitation, and can have a wide variety of temperatures. (b) Arctic tundra has low average precipitation and cold temperatures. (c) Temperate grasslands are characterized by scarce and erratic precipitation and greatly fluctuating temperatures. (d) Tropical rainforests are hot and humid (e) Temperate deciduous forests have moderate temperatures and abundant rainfall. 3. Why do deserts and arctic tundra support a much smaller biomass of animals than do tropical forests? Why do most animals in a tropical rain forest live in its trees? Answer: These areas contain fewer vegetative species than other ecosystems, and as the biomass of the producer species (plants) is small, the biomass of animals will be also be less than in these ecosystems. This follows the second law of thermodynamics and the loss of energy/biomass through successive trophic levels. More productive ecosystems such as tropical rain forests have more producers/plants that provide an abundance of food sources for herbivores and other animal species in these regions. More animals are found in these tropical regions. Animals tend to congregate in the trees because of the shelter provided and the abundant food found there. 4. How might the distribution of the world’s forests, grasslands, and deserts shown in Figure 7-7 differ if the prevailing winds shown in 7-3 did not exist? Answer: We would likely find a more even distribution of biomes on the face of the earth, without things like deserts appearing intermittently. 5. What biomes are best suited for: (a) raising crops, and (b) grazing livestock? Use the three scientific principles of sustainability to come up with three guidelines for growing food and grazing livestock in these biomes on a more sustainable basis. Answer: (a) Temperate grasslands are best suited for growing crops. Four sustainability guidelines to consider are: grow crops that are native to the area and that thrive under the normal rainfall and sunlight for the area; grow a wide variety of crops using polyculture, which enhances biodiversity; use best management practices such as no-till agriculture, which will help maintain nutrient recycling and minimize soil erosion, and use integrated pest management techniques to control the population of potential pest species. (b) Temperate grasslands are best suited for grazing livestock. (In the tropics the savanna contains large numbers of grazing herds of animals that are sometimes hunted as a food source.) Four sustainability guidelines to consider are: graze animals that are native to the area as these are best adapted for the environmental conditions of the region in terms of sunlight, temperature, and rainfall; graze a wide number of different animal species, which optimizes the biodiversity of the area; allow animal wastes/manure to remain in the grazing area, which promotes local nutrient recycling, and limit the numbers in the populations of the grazing animals, which will ensure that overgrazing does not occur. 6. What do you think might happen if all or most of the world’s glaciers melted? Write a brief scenario describing the resulting problems and ways in which you think mountainous nations would deal with the problems. Answer: This scenario could cause widespread problems for people who are dependent upon the melt water derived from glaciers. Additionally, glaciers reflect a lot of solar radiation, so without them, the local climate may be severely altered. Mountainous nations may initially face flooding as the glaciers melt, and later drought conditions. 7. What type of biome do you live in? List three ways in which your lifestyle could be contributing to the degradation of this biome. Answer: Answers will vary by region. Ways in which lifestyle harms the local biome will vary as well, but may include habitat destruction from development and agriculture, pollution from transportation and industry, and unsustainable water use, in terms of over-exploitation or pollution. 1. Deforestation: Cutting down trees for urban development or agriculture reduces habitat and biodiversity. 2. Pollution: Emissions from vehicles and industrial activities can contaminate air and water, harming plant and animal life. 3. Climate Change: Excessive greenhouse gas emissions contribute to global warming, altering weather patterns and affecting local ecosystems. 8. You are the defense attorney arguing in court for sparing a tropical rainforest from being cut. Give your three most important arguments for the defense of this ecosystem. Answer: Compelling arguments for the defense of tropical forests are that an intact tropical forest ecosystem contains more biodiversity per unit area than any other ecosystem, these forests help regulate global weather patterns, and forests act as carbon sinks, tying up carbon that would otherwise be contributing to the climate change phenomenon. 1. Biodiversity: Tropical rainforests are home to a vast array of species, many of which are found nowhere else. Protecting the rainforest preserves this unique biodiversity. 2. Climate Regulation: Rainforests play a crucial role in regulating the global climate by absorbing carbon dioxide and producing oxygen, which helps mitigate climate change. 3. Indigenous Rights: Many indigenous communities depend on rainforests for their livelihood and cultural practices. Destroying the rainforest threatens their homes and way of life. 9. Congratulations! You are in charge of the world. What are the three most important features of your plan to help sustain the earth’s terrestrial biodiversity? Answer: Student answers will vary but could include: protect all habitats from further destruction and degradation; implement restoration programs in habitats that have been affected already; educate people as to the principles of sustainability and biodiversity and encourage lifestyle changes to meet certain minimum standards for sustainability; educate and empower women in all countries, and encourage replacement level fertility on a global scale by making free family planning available to everyone. 1. Protecting Habitats: Establish and enforce large-scale protected areas and wildlife corridors to conserve natural habitats and maintain ecosystem integrity. 2. Sustainable Practices: Promote and implement sustainable agriculture, forestry, and fishing practices to reduce environmental impact and resource depletion. 3. Conservation Education: Increase global awareness and education on biodiversity conservation to foster community involvement and support for protection efforts. 10. List two questions that you would like to have answered as a result of reading this chapter. Answer: 1. How can we effectively balance economic development with biodiversity conservation to ensure both progress and ecological health? 2. What are the most successful strategies for restoring degraded ecosystems and reintroducing native species? Data Analysis In this chapter you learned how long-term variations in the average temperature and average precipitation play a major role in determining the types of deserts, forests, and grasslands found in different parts of the world. Below are typical annual climate graphs for a tropical grassland (savanna) in Africa and a temperate grassland in the mid-western United States. 1. In what month (or months) does the most precipitation fall in each of these areas? 2. What are the driest months in each of these areas? 3. What is the coldest month in the tropical grassland? 4. What is the warmest month in the temperature grassland? 1. Answer: Most precipitation Tropical grassland: January and February Temperate grassland: Last of April to early May 2. Answer: Driest Tropical grassland: June Temperate grassland: January 3. Answer: June 4. Answer: June Chapter 8 Aquatic Biodiversity Summary 1. The basic types of aquatic life zones are the surface, middle, and bottom layers. The life in aquatic life zones is influenced by temperature, access to sunlight for photosynthesis, dissolved oxygen content, and availability of nutrients. 2. The major types of saltwater life zones are the coastal zone and the open sea. Coastal ecosystems contain estuaries, wetlands, and mangrove swamps. Because of their close proximity to man’s activities, they are under constant strain from water pollution, industrial run-off, construction and soil erosion, agricultural pesticides flowing into rivers and streams, and aquaculture farming. The open sea contains the euphotic zone, which is the lighted upper zone of the ocean. The bathyal zone is in the middle and is dimly lit. The lowest zone, the abyssal zone, is dark and very cold. But all are being affected by human activities: over-harvesting, oil spills, filling-in of wetland areas, agricultural and industrial development and pollution, rising sea levels, and careless fishing/trawling techniques. 3. The major types of freshwater life zones are lakes, wetlands, and rivers. Human activities, such as dams or canals; flood control levees and dikes; and industrial, urban, agricultural pollutants all affect the flow and health of freshwater zones. Much of U.S. wetlands have been drained and filled to farm and/or to construct homes and businesses. These actions increase flood potential and encourage droughts. People overfish the waters; pollute the streams, rivers, and lakes; and dump excessive nutrients from pesticides and waste lots into the fresh water sources. 4. We must protect aquatic life zones from the pollutants, water controls, and deterioration that we press upon them every day. Key Questions and Concepts 8-1 What is the general nature of aquatic systems? CORE CASE STUDY: Coral reefs are highly biodiverse, and they provide us with many ecological and economic services. They serve to sequester carbon, buffer coastlines, and provide valuable habitat. Globally, 19% of reefs have been destroyed and another 20% have been degraded. An additional 25–33% could be lost in the coming decades. Degradation and loss of reefs is an indicator that should serve as a warning about threats to the health of oceans. A. Saltwater and freshwater aquatic zones cover about 71% of the earth’s surface. B. Salinity of the water determines the major types of organisms found in an aquatic environment. C. There are four major types of organisms in aquatic systems: 1. Plankton are free-floating, weakly swimming, generally one-celled organisms. There are three major types of plankton: phytoplankton (plant plankton), zooplankton (animal plankton), and ultra plankton, which are no more than two micrometers wide and are photosynthetic bacteria. 2. Ultra plankton may be responsible for as much as 70% of the primary productivity near the ocean surface. 3. Nekton is a second group of organisms. These are fish, turtles, and whales. 4. Benthos are bottom dwellers. 5. Decomposers are a fourth group. These organisms break down organic matter. D. In aquatic systems, the key factors determining the types and numbers of organisms are temperature, dissolved oxygen, sunlight availability, and nutrient availability. 1. Photosynthesis is largely limited to the upper layers, or photic zone, which can be diminished by turbidity. 8-2 Why are marine aquatic systems important? A. Oceans have two major life zones: the coastal zone and the open sea. B. The coastal zone interacts with the land, and so is much affected by human activities. 1. Ecosystems in coastal zones have a high net primary productivity per unit area. They constitute 10% of the oceans and contain 90% of all marine species. 2. There is ample sunlight, and nutrients flow from land and wind/currents distribute them. 3. The coastal zone extends from the high-tide mark on land to the edge of the continental shelf. 4. Estuaries and coastal wetlands are subject to tidal rhythms, runoff from land, and seawater that mixes with freshwater and nutrients from rivers and streams. 5. Mangrove forest swamps grow in sheltered regions of tropical coasts. 6. Coastal wetlands/estuaries make nutrients available due to constant stirring of bottom sediment. 7. These areas filter toxic pollutants and excess plant nutrients, reduce storm damage, and provide nursery sites for aquatic species. C. Organisms living in the intertidal zone have adapted ways to survive the daily changes in wet/dry conditions and changes in salinity. D. Barrier beaches/sandy shores are gently sloping. Organisms tunnel or burrow in the sand to survive daily changes in conditions. E. Low, sandy, narrow islands that form offshore from a coastline are barrier islands. They generally run parallel to the shore. F. Coral reefs are home to ¼ of all marine species. G. The open sea is divided into three vertical zones based primarily on penetration of light. 1. The euphotic zone is lighted, has floating phytoplankton carrying on photosynthesis, and has low nutrient levels except at upwellings. a. Dissolved oxygen level is high. 2. The bathyal zone is the dimly lit middle zone; no producers are in this zone. Zooplankton and smaller fish live in this zone. 3. The abyssal zone is dark, very cold with little dissolved oxygen. a. Organisms in this area are deposit feeders, or filter feeders. b. Hydrothermal vents are present in some areas with specialized bacteria that feed on chemical nutrients and are food for other organisms. c. Low average primary productivity and NPP occurs, but oceans are so large they make the largest contribution to NPP overall. 8-3 How have human activities affected marine ecosystems? A. Human activities are greatly affecting the ecological and economic services provided by marine ecosystems. 1. Studies suggest 41% of the world’s ocean area has been heavily affected by human activities. 2. About 45% of the global population lives along coasts, and that figure is expected to rise. 3. Major threats to marine systems include coastal development, degradation of wetlands and estuaries, over-fishing, non-point and point source pollution, habitat destruction, invasive species, and climate change. CASE STUDY: Chesapeake Bay is the largest estuary in the United States. Population pressures and pollution have led to severe environmental problems in the region. An integrated program involving diverse groups has been effective in recent years at alleviating the severity of some of these pressures. Nevertheless, a recent decline in funding has slowed progress and environmental problems remain. New efforts to revitalize the project are promising. 8-4 Why are freshwater ecosystems important? A. Freshwater life zones include standing (lentic) bodies—such as lakes, ponds, and wetlands—and flowing (lotic) systems such as streams and rivers. B. Lakes are large natural bodies of standing water found in depressions. 1. Rainfall, runoff, groundwater seepage and stream drainage feed lakes. 2. Generally consist of four distinct zones depending on depth and distance from shore. a. Littoral zone is open, sunlit surface water away from shore and is the most productive area for food and oxygen production. b. The limnetic zone is the open sunlit surface away from the shore that extends to the depth that sunlight reaches. c. Profundal zone is deep oven water too dark for photosynthesis. Oxygen levels are lower. d. Benthic zone consists of decomposers and detritus feeders. Fish swim from one zone to another. Sediment washing and dropping detritus feed this area. e. Oligotrophic lakes have small supplies of plant nutrients. f. Eutrophic lakes have large nutrient supplies. i. Human inputs can lead to cultural eutrophcation. g. Lakes between these two extremes are called mesotrophic lakes. C. Surface water is precipitation that does not infiltrate the ground or evaporate. 1. Runoff is surface water that flows into streams and rivers, and the area it drains is called a watershed or drainage basin. D. Three aquatic life zones, each with different conditions, can be identified along stream flow. 1. The source zone is narrow and fast moving. It dissolves large amounts of oxygen from air, and most plants are attached to rocks. Light is available, but is not very productive. 2. The transition zone forms wider, deeper streams that flow down gentler slopes. The water is warmer, with more nutrients, which supports more producers, but has slightly lower dissolved oxygen. 3. The floodplain zone has wider, deeper rivers. Water temperature is warmer; less dissolved oxygen is present and flow is slower. CASE STUDY: Coastal deltas and wetlands provide protection against flooding. When these areas are degraded, the effects of storm events can be intensified. Many deltas are shrinking rather than being maintained, because the sediments that normally build them are trapped behind dams upstream. Much of the city of New Orleans is now below sea level for this reason. Levees offer a temporary solution but will usually be breached by a strong storm. Climate change also suggests that sea level will be rising further. We now understand these processes, but the question is whether or not we will apply them to the systems that are at risk. E. Inland wetlands cover the land for a part of all of each year. Wetlands include swamps, marshes, prairie potholes, floodplains, and arctic tundra in summer. 1. Wetlands provide a variety of ecosystem services, including filtering waste, reducing flooding, replenishing stream flows, recharging aquifers, maintaining biodiversity, supplying valuable products, and providing recreation opportunities. 8-5 How have human activities affected freshwater ecosystems? A. Human activities have four major impacts on freshwater systems. 1. Dams, diversions of canals fragment ~60% of world’s large rivers and destroy habitats. 2. Flood control dikes and levees alter rivers and destroy aquatic habitats. 3. Cities and farmlands add pollutants. 4. Many inland wetlands have been drained or altered. CASE STUDY: More than half of the inland wetlands that existed in the United States in the 1600s no longer exist. About 80% are now used to grow crops and the rest have been lost to mining, forestry, and oil and gas extraction. This has greatly increased the flood and drought damage in the United States. Teaching Tips Large Lecture Courses: Ask the members of the class to brainstorm ways in which they may inadvertently be putting pollutants into their waterways. List these on the board for reference. As the students run out of suggestions, question them Socratically about their activities and the pollution that is generated around them. Bring up such activities as fertilizing the lawn and garden or washing the car. Draw the connection between general classes of pollutants and everyday activities that often seem benign. Smaller Lecture Courses: Explore the manner in which the local community augments or hinders the functioning of the hydrologic system, and in particular the extent to which the way we live determines how much water runs off versus infiltrating. Explain the ramifications of both scenarios, in terms of flooding, recharging groundwater resources, cleaning the water of toxins and pollutants, etc. It may be valuable if the technology is available in your classroom to project a Google Earth map of the surrounding region. This will help students visualize the extent to which community design dictates the flow of water. Perhaps there is a levee system, a dam, or a reservoir in your area. If not, you might focus on the relative abundance of pavement versus vegetated open space to draw conclusions about what this entails for the hydrologic cycle. Key Terms aquatic life zones benthos coastal wetland coastal zone cultural eutrophication decomposers drainage basin eutrophic lake freshwater inland wetlands intertidal zone lakes marine mesotrophic lake nekton oligotrophic lakes open sea plankton runoff saltwater surface water turbidity watershed Term Paper Research Topics 1. Aquatic life zones: coastal zones, beaches, coastal wetlands, coral reefs, the abyssal zone. 2. Freshwater life zones: lakes, streams, and rivers. 3. Seasonal turnover in lakes. 4. What is life like at hydrothermal vents in the deep ocean? 5. Wetlands protection. 6. Prevention of beach erosion 7. Coastal cleanup strategies. 8. Endangered species of the coast. 9. What can be done to prevent coral bleaching? Discussion Topics 1. In what ways do humans disrupt the hydrologic cycle? What are the impacts of these disruptions? Answer: Humans disrupt the hydrologic cycle through activities like deforestation, urbanization, and agriculture, which alter water flow, reduce infiltration, and increase runoff. These disruptions can lead to increased flooding, reduced groundwater recharge, and water quality degradation, affecting ecosystems and human water supplies. 2. What are the ecological contributions of the oceans? Answer: Oceans play crucial ecological roles by regulating climate, providing habitat for marine life, supporting food chains, and cycling nutrients. They also absorb carbon dioxide, helping to mitigate climate change, and offer resources such as food and medicinal compounds. 3. What is the ecological significance of coral reefs? Are there any reefs in your area? If not, why should you be concerned about them? Answer: Coral reefs are ecologically significant as they provide habitat and shelter for a diverse range of marine species, support fisheries, and protect coastlines from erosion. Even if there are no reefs in your area, they are important globally for biodiversity and ecological health, impacting oceanic and coastal systems. 4. What are the valuable ecological functions performed by wetlands? What are some environmental problems associated with coastal and inland wetlands? Where could you find an intact wetland in your area? Answer: Wetlands perform crucial functions such as water filtration, flood regulation, and providing habitat for wildlife. Environmental problems include pollution, drainage for development, and habitat loss. Intact wetlands might be found in protected areas, nature reserves, or conservation zones in your region. 5. What kinds of activities lead to eutrophication in lakes? Do you contribute to this process in any way? Answer: Activities leading to eutrophication include agricultural runoff, industrial discharge, and wastewater from urban areas, which introduce excess nutrients like nitrogen and phosphorus into lakes. If you use fertilizers or contribute to wastewater generation, you might contribute to this process. 6. Can you define or roughly delineate the watershed in your area? Why is it important to take a watershed approach to managing freshwater systems? Answer: A watershed is the land area that drains into a particular water body, such as a river or lake. Managing freshwater systems through a watershed approach is important because it considers the entire area influencing water quality and quantity, ensuring comprehensive management of resources and pollution control. 7. Should we retreat from the beach? Should houses built on barrier beaches have access to insurance? Answer: Retreating from the beach may be necessary due to rising sea levels and increased storm frequency, which can reduce risk and property damage. Access to insurance for houses on barrier beaches can be contentious, as it involves balancing risk management with affordability and responsible development practices. 8. Is your water supply affected by spring and fall turnovers? Answer: Yes, spring and fall turnovers can affect water supply by mixing water layers in lakes, which can influence temperature, oxygen levels, and nutrient distribution. This mixing can impact water quality and availability, especially if it leads to changes in algae growth or sediment resuspension. Activities and Projects 1. Arrange a field trip providing opportunities to compare and contrast aquatic life zones. What factors appear to be significant in determining the life found in each zone? 2. Ask students to bring to class and share examples of art, music, poetry, and other creative expressions of human thoughts and feelings about earth's aquatic life zones. Lead a class discussion on the subject of the human tendency to settle near water. 3. Are inland wetlands being drained and filled in your locale? Is there a nearby stream or river being subjected to excessive levels of pollution? Is it feasible for you and your class to "adopt" one of these disturbed ecosystems and help restore it to health? 4. Arrange a debate on the problems and alternatives of coastal zone management. Debate the proposition that we should severely restrict engineering approaches to beach stabilization and adopt a "retreat from the beach" strategy, emphasizing the preservation of coastal ecosystems and the ecosystem services they provide. Attitudes and Values 1. Are you aware of bodies of water in your area that affect local climate conditions and human developments? Answer: Yes, bodies of water such as lakes, rivers, or reservoirs can significantly influence local climate conditions by moderating temperatures and increasing humidity. They also impact human developments, affecting land use, infrastructure planning, and recreation, as well as providing resources and influencing agricultural practices. 2. Do humans have a right to use aquatic life zones in any way they wish? Do you see limits to freedom of choice? If so, what determines those limits? Answer: Humans do not have an unrestricted right to use aquatic life zones, as overexploitation and pollution can harm ecosystems and biodiversity. Limits are determined by environmental regulations, ethical considerations, and the need to maintain ecological balance and ensure the sustainability of aquatic resources for future generations. 3. Do you feel that humans have the power to alter the quality of aquatic life zones? Do you feel that humans can responsibly control their impact on these zones? Answer: Yes, humans have the power to alter the quality of aquatic life zones through activities like pollution, habitat destruction, and overfishing. While responsible management is possible through regulations, conservation efforts, and sustainable practices, it requires commitment and cooperation to effectively control and mitigate impacts on these important ecosystems. Additional Video Resources After the Storm (Documentary, free DVD or VHS) Looks at watersheds and their importance in various parts of the U.S. http://www.epa.gov/weatherchannel/video.html Blue Planet (Video series, Discovery Channel, 2001) Mammoth series, five years in the making, taking a look at the rich tapestry of life in the world's oceans. http://dsc.discovery.com/convergence/blueplanet/blueplanet.html Conserving America: The Wetlands (PBS, 1994) A four-part series on American Conservation of wetlands Conserving America: The Rivers (PBS, 1994) Conserving America: The Challenge on the Coast (PBS, 1994) Conserving America: The Wetlands (PBS, 1994) The End of the Line (DVD, 2010). This is an excellent documentary covering overfishing and the state of our oceans. The Habitable Planet: A Systems Approach to Environmental Science (Documentary series, 2007). Videos 2, 3, 5, 7, 8, and 9. http://www.learner.org/resources/series209.html Last Journey for the Leatherback? Looks at the effects of overfishing on sea turtles. http://www.greentreks.org/naturalheroes/season2/lastjourney.asp Ocean Oasis (Documentary, San Diego Natural History Museum, 2001) Biodiversity in the Sea of Cortez, and the deserts of Baja. http://www.oceanoasis.org/toc.html We all Live Downstream (Documentary, 1991) A look at pollution in the Mississippi River and the effects on human health. http://www.videoproject.com/wea-281-v.html Web Resources Bridge http://www.vims.edu/bridge/ A variety of resources for teachers that may be adaptable to the college level. Centers for Ocean Sciences Education Excellence http://www.cosee.net/ Contains a variety of resources for ocean education. EPA Wetlands Education http://www.epa.gov/owow/wetlands/education/ Contains a variety of resources for teaching about the significance of wetlands. Suggested Answers to End of Chapter Review Questions Review Questions 1. Review the Key Questions and Concepts for this chapter on p. 1639. What is a coral reef and why should we care about coral reefs? What is coral bleaching? Answer: • Coral reefs are among the world’s oldest, most diverse, and most productive ecosystems. A coral reef forms when massive colonies of tiny animals called polyps die, leaving their empty crusts behind as part of a platform for more reef growth in clear, warm coastal waters of the tropics and subtropics. The resulting elaborate network of crevices, ledges, and holes serves as calcium carbonate “condominiums” for a variety of marine animals. • Coral reefs provide important ecological and economic services. They help moderate atmospheric temperatures by removing CO2 from the atmosphere, and they act as natural barriers that protect 15% of the world’s coastlines from erosion caused by battering waves and storms. They also provide habitats for one-quarter of all marine organisms. Economically, coral reefs produce about one-tenth of the global fish catch—one-fourth of the catch in developing countries—and they provide jobs and building materials for some of the world’s poorest countries. Coral reefs also support important fishing and tourism industries. Finally, these biological treasures give us an underwater world to study and enjoy. Each year, more than 1 million scuba divers and snorkelers visit coral reefs to experience these wonders of aquatic biodiversity. • Coral bleaching occurs when stresses such as increased temperature cause the algae, upon which corals depend for food, to die off, leaving behind a white skeleton of calcium carbonate. 2. What percentage of the earth’s surface is covered with water? What is an aquatic life zone? Answer: Distinguish between a saltwater (marine) life zone and a freshwater life zone and give two examples of each. What major types of organisms live in the top, middle, and bottom layers of aquatic life zones? Define plankton and describe three types of plankton. Distinguish among nekton, benthos, and decomposers and give an example of each. List five factors that determine the types and numbers of organisms found in the three layers of aquatic life zones? What is turbidity, and how does it occur? Describe one of its harmful impacts. • Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface, and oceans dominate the planet. 71% of the earth’s surface is covered with salty ocean water. • The aquatic equivalents of biomes are called aquatic life zones. Aquatic life zones are classified into two major types: saltwater or marine (oceans and their accompanying estuaries, coastal wetlands, shorelines, coral reefs, and mangrove forests) and freshwater (lakes, rivers, streams, and inland wetlands). Although some systems such as estuaries are a mix of saltwater and freshwater, we classify them as marine systems for purposes of discussion. • Saltwater and freshwater life zones contain several major types of organisms. One major type consists of weakly swimming, free-floating plankton, which can be divided into three groups, the first of which is phytoplankton, which includes many types of algae. The second plankton group is zooplankton, consisting of primary consumers (herbivores) that feed on phytoplankton and secondary consumers that feed on other zooplankton. A third group consists of huge populations of much smaller plankton called ultra plankton—extremely small photosynthetic bacteria that may be responsible for 70% of the primary productivity near the ocean surface. A second major type of aquatic organisms is nekton, strongly swimming consumers such as fish, turtles, and whales. A third type, benthos, consists of bottom dwellers such as oysters, which anchor themselves to one spot; clams and worms, which burrow into the bottom; and lobsters and crabs, which walk about on the sea floor. A fourth major type is decomposers (mostly bacteria), which break down organic compounds in the dead bodies and wastes of aquatic organisms into nutrients that can be used by aquatic primary producers. Most forms of aquatic life are found in the surface and middle layers of saltwater and freshwater systems. • The key factors determining the types and numbers of organisms found in the different layers are temperature, dissolved oxygen content, availability of food, and availability of light and nutrients required for photosynthesis, such as carbon (as dissolved CO2 gas), nitrogen (as NO3-), and phosphorus (mostly as PO43-). • The depth of the zone through which sunlight can penetrate can be reduced when the water is clouded by excessive algal growth resulting from nutrient overloads. This cloudiness, called turbidity, can occur naturally, such as from algal growth, or can result from disturbances such as clearing of land, which causes silt to flow into bodies of water. This is one of the problems plaguing coral reefs, as excessive turbidity due to silt runoff prevents photosynthesis and causes the corals to die. 3. What major ecological and economic services are provided by marine systems? What are the three major life zones in an ocean? Distinguish between the coastal zone and the open sea. Distinguish between an estuary and a coastal wetland and explain why each have high net primary productivity. Describe some of the interactions among species in a coastal marsh ecosystem. Explain the importance of sea grass beds. What is a mangrove forest and what is its ecological and economic importance? What is the intertidal zone? Distinguish between rocky and sandy shores and describe some of the organisms often found on each type of shoreline. Answer: • Ecological services provided by marine systems include: climate moderation, CO2 absorption, nutrient cycling, waste treatment, reduced storm impact, habitats and nursery areas, genetic resources and biodiversity and scientific information. • Economic services provided by marine systems include food, animal and pet feed, pharmaceuticals, harbors and transportation routes, coastal habitats for humans, recreation, employment, oil and natural gas, minerals and building materials. • Marine life is found in three major life zones: the coastal zone, open sea, and ocean bottom. • The coastal zone is the warm, nutrient-rich, shallow water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf (the submerged part of the continents). It makes up less than 10% of the world’s ocean area, but it contains 90% of all marine species and is the site of most large commercial marine fisheries. The sharp increase in water depth at the edge of the continental shelf separates the coastal zone from the vast volume of the ocean called the open sea. • Estuaries are where rivers meet the sea. They are partially enclosed bodies of water where seawater mixes with freshwater as well as nutrients and pollutants from streams and runoff from the land. • Estuaries and their associated coastal wetlands—coastal land areas covered with water all or part of the year—include river mouths, inlets, bays, and salt marshes in temperate zones, and mangrove forests in tropical zones. • Decomposition occurs rapidly in coastal marshes and there are ample inputs of nutrients from runoff. This makes for a very productive ecosystem that is attractive for marine life as well as avian diversity. • Sea grass beds are highly productive and physically complex systems that support a variety of marine species. They also help to stabilize shorelines and reduce wave impacts. • Mangrove forests are tropical coastal wetlands with deep-rooted mangrove trees. They are the tropical equivalent of salt marshes. They are found along some 70% of gently sloping sandy and silty coastlines in tropical and sub-tropical regions, especially Southeast Asia. The dominant organisms in these nutrient- rich coastal forests are mangroves. • Mangrove forests help to maintain water quality in tropical coastal zones by filtering toxic pollutants, excess plant nutrients, and sediments, and by absorbing other pollutants. They provide food, habitats, and nursery sites for a variety of aquatic and terrestrial species. They also reduce storm damage and coastal erosion by absorbing waves and storing excess water produced by storms and tsunamis. Historically, they have sustainably supplied timber and fuel wood to coastal communities. Loss of mangroves can lead to polluted drinking water, caused by inland intrusion of saltwater into aquifers that are used to supply drinking water. • The gravitational pull of the moon and sun causes tides to rise and fall about every 6 hours in most coastal areas. The area of shoreline between low and high tides is called the intertidal zone. • On some coasts, steep rocky shores are pounded by waves. The numerous pools and other habitats in their intertidal zones contain a great variety of species that occupy different niches in response to daily and seasonal changes in environmental conditions such as temperature, water flows, and salinity. • Other coasts have gently sloping barrier beaches, or sandy shores, that support other types of marine organisms. Most of them keep hidden from view and survive by burrowing, digging, and tunneling in the sand. 4. Explain the importance of coral reefs and some of the interactions among the species in such systems. Describe the three major zones in the open sea. What human activities pose major threats to marine systems and to coral reefs? Answer: • Coral reefs are among the world’s most diverse and productive ecosystems. Economically, they are responsible for 1/10 of the world’s fish catch, and provide for economic development through ecotourism. Coral reefs are formed by massive colonies of tiny animals called polyps (close relatives of jellyfish). Coral reefs are the result of a mutually beneficial relationship between the polyps and tiny single-celled algae called zooxanthellae that live in the tissues of the polyps. In this example of mutualism, the algae provide the polyps with food and oxygen through photosynthesis, and help produce calcium carbonate, which forms the coral’s skeleton. Algae also give the reefs their stunning coloration. The polyps, in turn, provide the algae with a well-protected home and some of their nutrients. • The euphotic zone is the brightly lit upper zone, where drifting phytoplankton carry out about 40% of the world’s photosynthetic activity. The bathyal zone is the dimly lit middle zone, which receives little sunlight and therefore does not contain photosynthesizing producers. The lowest zone, called the abyssal zone, is dark and very cold. There is no sunlight to support photosynthesis, and this zone has little dissolved oxygen. Nevertheless, the deep ocean floor is teeming with life. • Net primary productivity is low because nutrients and dissolved oxygen tend to be low. • Major threats to marine systems from human activities include: ○ Coastal development, which destroys and pollutes coastal wetlands ○ Mangrove forests have been lost ○ Beaches are eroding ○ Bottom habitats have been degraded by dredging ○ Coral reefs have been badly damaged • Nine human activities threatening coral reefs include: ○ Ocean warming ○ Rising acidity ○ Soil erosion ○ Algal growth ○ Bleaching ○ Rising sea levels ○ Increased UV exposure ○ Damage from anchors ○ Damage from fishing and diving 5. Explain why the Chesapeake Bay is an estuary in trouble. What is being done about some of its problems? Answer: • Since 1960, the Chesapeake Bay has been in serious trouble from water pollution, mostly because of human activities. One problem is population growth. Between 1940 and 2007, the number of people living in the Chesapeake Bay area grew from 3.7 million to 16.6 million. The estuary receives wastes from point and non-point sources scattered throughout a huge drainage basin. Phosphate and nitrate levels have risen sharply in many parts of the bay, causing algal blooms and oxygen depletion. Commercial harvests of its once-abundant oysters, crabs, and several important fishes have fallen sharply since 1960 because of a combination of pollution, overfishing, and disease. • In 1983, the United States implemented the Chesapeake Bay Program Strategies include establishing land- use regulations in the bay’s six watershed states to reduce agricultural and urban runoff, banning phosphate detergents, upgrading sewage treatment plants, and monitoring 3 days. Between 1985 and 2000, phosphorus levels declined 27%, nitrogen levels dropped 16%, and grasses growing on the bay’s floor have made a comeback. 6. What major ecological and economic services do fresh-water systems provide? What is a lake? What four zones are found in deep lakes? Distinguish among oligotrophic, eutrophic, and mesotrophic lakes. What is cultural eutrophication? Answer: • Ecological services provided by freshwater systems include: climate moderation, nutrient cycling, waste treatment, flood control, groundwater recharge, habitats, genetic resources and biodiversity and scientific information. • Economic services provided by freshwater systems include: food, drinking water, irrigation water, hydroelectricity, transportation corridors, recreation and employment. • Lakes are large natural bodies of standing freshwater formed when precipitation, runoff, streams and rivers, and groundwater seepage fill depressions in the earth’s surface. • Four distinct zones that are defined by their depth and distance from shore: ○ Littoral zone ○ Limnetic zone ○ Profundal zone ○ Benthic zone • Lakes that have a small supply of plant nutrients are called oligotrophic (poorly nourished) lakes. • A lake with a large supply of nutrients needed by producers is called a eutrophic (well-nourished) lake. Lakes that fall somewhere between the two extremes of nutrient enrichment are called mesotrophic lakes. • Human inputs of nutrients from the atmosphere and from nearby urban and agricultural areas can accelerate the eutrophication of lakes, a process called cultural eutrophication. 7. Define surface water, runoff, and watershed (drainage basin). Describe the three zones that a stream passes through as it flows from mountains to the sea. Describe the relationships between dams, deltas, wetlands, hurricanes, and flooding in New Orleans, Louisiana (USA). Answer: • Precipitation that does not sink into the ground or evaporate is surface water. It becomes runoff when it flows into streams. A watershed, or drainage basin, is the land area that delivers runoff, sediment, and dissolved substances to a stream. • Three zones in the downhill flow of water: source zone, which contains mountain (headwater) streams; transition zone, which contains wider, lower-elevation streams; and floodplain zone, which contains rivers that empty into larger rivers or into the ocean. • The U. S. state of Louisiana has lost more than a fifth of its wetlands to coastal development. The Mississippi River once delivered huge amounts of sediments to its delta each year. But the multiple dams, levees, and canals in this river system funnel much of this load through the wetlands and out into the Gulf of Mexico. Instead of building up delta lands, this causes them to subside. Other human processes that are increasing such subsidence include extraction of groundwater and oil and natural gas. As freshwater wetlands are lost, saltwater from the Gulf has intruded and killed many plants that depended on river water, further degrading this coastal aquatic system. This helps to explain why the U. S. city of New Orleans, Louisiana, which was flooded by Hurricane Katrina in 2005, is 3 meters below sea level. 8. Give three examples of inland wetlands and explain the ecological and economic importance of such wetlands. Answer: • Three examples of inland wetlands: ○ Marshes (dominated by grasses and reeds with few trees) ○ Swamps (dominated by trees and shrubs) ○ Prairie potholes (depressions carved out by ancient glaciers) • Inland wetlands are ecologically important because they provide a number of free ecological and economic services, which include: ○ Filtering and degrading toxic wastes and pollutants ○ Reducing flooding and erosion by absorbing storm water and releasing it slowly and by absorbing overflows from streams and lakes ○ Helping to replenish stream flows during dry periods ○ Helping to recharge groundwater aquifers ○ Helping to maintain biodiversity by providing habitats for a variety of species ○ Supplying valuable products such as fish and shellfish, blueberries, cranberries, wild rice, and timber ○ Providing recreation for birdwatchers, nature photographers, boaters, anglers, and waterfowl hunters 9. What are four ways in which human activities are disrupting and degrading freshwater systems? Describe inland wetlands in the United States in terms of the area of wetlands lost and the resulting loss of ecological and economic services. Answer: • Human activities are disrupting and degrading many of the ecological and economic services provided by freshwater rivers, lakes, and wetlands in four major ways: ○ Dams and canals fragment about 40% of the world’s 237 large rivers. They alter and destroy terrestrial and aquatic wildlife habitats along rivers and in coastal deltas and estuaries by reducing water flow and increasing damage from coastal storms. ○ Flood control levees and dikes built along rivers disconnect the rivers from their floodplains, destroy aquatic habitats, and alter or reduce the functions of nearby wetlands. ○ Cities and farmlands add pollutants and excess plant nutrients to nearby streams, rivers, and lakes. ○ Many inland wetlands have been drained or filled to grow crops or have been covered with concrete, asphalt, and buildings. • More than half of the inland wetlands estimated to have existed in the continental United States during the 1600s no longer exist. About 80% of lost wetlands were destroyed to grow crops. The rest were lost to mining, forestry, oil and gas extraction, highways, and urban development. This loss of natural capital has been an important factor in increased flood and drought damage in the United States—more examples of unnatural disasters. 10. What are this chapter’s three big ideas? What is the relationship between coral reefs and the three principles of sustainability? Answer: • The three big ideas are: ○ Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface, and oceans dominate the planet. ○ The earth’s aquatic systems provide important ecological and economic services. ○ Human activities threaten biodiversity and disrupt ecological and economic services provided by aquatic systems. • Reliance on solar energy: human reliance on fossil fuels causes warmer ocean temperatures, which lead to coral bleaching, and increased ocean acidity, which causes reef dissolution. A rise in sea level could destroy coral reefs. • Biodiversity: destruction of coral reefs reduces biodiversity, as does introduction of invasive species. • Population control: increased human population has caused habitat destruction from coastal development, overfishing, and pollution. Human recreational use of reefs causes damage from anchors, fishing, and diving. • Nutrient cycling: runoff of non-point source pollution from pesticides, fertilizers, and livestock causes pollution. Critical Thinking The following are examples of the material that should be contained in possible student answers to the end of chapter Critical Thinking questions. They represent only a summary overview and serve to highlight the core concepts that are addressed in the text. It should be anticipated that the students will provide more in-depth and detailed responses to the questions depending on an individual instructor’s stated expectations. 1. What are three steps governments and industries could take to protect the remaining coral reefs (Core Case Study) from harmful activities? What are three ways in which individuals can help to protect those reefs? Answer: Government and industry could limit coastal development, pollution, and overfishing as a means of protecting reefs. They might also work to limit emissions of greenhouse gases in order to diminish the effects of global climate change. Individuals could avoid buying products harvested from reefs, support sustainable development along coastlines, and limit their contribution to climate change by reducing emissions and their carbon footprint. 2. Suppose you are a defense attorney arguing in court for protecting a coral reef (Core Case Study) from harmful human activities. Give you three most important arguments for the defense of the ecosystem. Answer: Coral reefs are home to an inordinate amount of the ocean’s biodiversity. Coral reefs protect coastlines, and coral reefs provide economic sustainability if well-managed, given the amount of the total fish catch they produce. 3. Why do aquatic plants such as phytoplankton tend to be very small, whereas most terrestrial plants such as trees tend to be larger and have more specialized structures such as stems and leaves for growth? Answer: Aquatic plants such as phytoplankton tend to be small as they are free-floating in the upper layer or euphotic zone of the ocean. Not only do they undergo photosynthesis, which introduces oxygen into the water to sustain other marine life, they are also the base of the food web for marine life, beginning with the smallest of aquatic animal species. The turnover rate of these small plants is quite high; reproduction and consumption rates tend to be rapid, so they do not have the chance to get very big. Sunlight does not penetrate to the sea floor, so large rooted plants are unable to grow in the depths of the ocean. Only in shallower coastal areas can plants such as these grow, as in the kelp forests off the coast of California. 4. Why are some aquatic animals, especially marine mammals such as whales, extremely large compared with terrestrial animals? Answer: Marine animals such as whales can be extremely large when compared to land animals. If such a large animal existed on the earth they would have to have bone structures that would carry their large weights, and would probably move at a very slow pace. The buoyancy of water enables whales to become very large, and at the same time they are still be able to move quickly through the water to obtain food or escape predation. These grazing animals of the sea are able to travel long distances all over the globe to obtain food and survive. Terrestrial grazing animals such as elephants tend to have a more limited range on which the herd can use for food and habitat. 5. How would you respond to someone who proposes that we use the deep portions of the world’s oceans to deposit our radioactive and other hazardous wastes because the deep oceans are vast and are located far away from human habitats? Give reasons for your response. Answer: I would oppose the suggestion that we use the deep oceans as a place to dispose of radioactive or hazardous waste. Although the abyssal zone is dark and cold, it does contain enough nutrients to support a large number of species. Some of these species travel closer to the ocean surface or higher ocean levels each day as part of their life cycles. This connects the different life zones in the ocean. Dumping wastes in the ocean depths would have a detrimental effect on the species of the deep. This is the part of the ocean that we are slowing beginning to understand as we develop technology that allows humans to study the deep. There are also deep ocean currents that could bring the dumped materials to the surface through the natural upwelling that takes place. The enormous pressures that are commonly found in the deep oceans would also be problematic for the design of safe storage containers to house the hazardous materials. They may break open and leak out their contents to be distributed around the world’s ocean system. 6. Suppose a developer builds a housing complex overlooking a coastal salt marsh and the result is pollution and degradation of the marsh. Describe the effects of such a development on the wildlife of the marsh, assuming at least one species is eliminated as a result. Answer: The loss of a species due to environmental change associated with the development would severely disrupt the complex interaction amongst organisms within the salt marsh. This could occur as a result of pollution or habitat fragmentation and disruption. The intricate relationships amongst species involve the transfer of matter and energy. Loss of one or more species would entail unpredictable changes in ecosystem functions. 7. How does a levee built on a river affect species such as deer and hawks living in a forest overlooking the river? Answer: All species in the system will be inadvertently affected by the levee. Levees disrupt seasonal variations in river flows and hinder the distribution of sediments. They interfere with the growth of insect populations and disrupt the spawning cycles of fishes and the breeding cycles of shorebirds. These fundamental alterations severely disrupt the entire food web. Hawks and deer will be affected by changes in resource distribution and food availability. There will be changes in competition as biodiversity changes and non-native species are introduced. 8. Suppose you have a friend who owns property that includes a freshwater wetland, and the friend tells you he is planning to fill the wetland to make room for his lawn and garden. What would you say to this friend? Answer: You might explain to this friend the important roles that wetlands play. First of all, you should mention that wetlands are critical habitat for numerous rare species that flourish in that unique environment. You might add that a diversity of bird species is likely to visit the wetland. You could also try appealing to his sense of practicality by explaining that wetlands mediate the effects of storm waters and flooding, that they serve to purify water, and ultimately recharge groundwater supplies. 9. Congratulations! You are in charge of the world. What are the three most important features of your plan to help sustain the earth’s aquatic biodiversity? Answer: Three important features would be to enact global legislation to protect and restore: (1) coral reefs, (2) inland and coastal wetlands, and (3) fisheries, so that they are operated only by harvesting the maximum sustainable yield. These three things would help to sustain the world’s aquatic biodiversity. 10. List two questions that you would like to have answered as a result of reading this chapter. Answer: 1. How can companies balance local adaptation with maintaining a unified global brand? 2. What are the challenges and strategies for managing brand equity in new international markets? Data Analysis Assessing the Recovery of Coral Reefs in Belize At least 25% of the world’s coral reefs have been severely damaged. A number of factors have played a role in this serious loss of aquatic biodiversity (Figure 8-13), including ocean warming, sediment from coastal soil erosion, excessive algae growth from fertilizer runoff, coral bleaching, rising sea levels, overfishing, and damage from hurricanes. In 2005, scientists Nadia Bood, Melanie McField, and Rich Aronsosn conducted research to evaluate the recovery of coral reefs in Belize from the combined effects of mass bleaching and Hurricane Mitch in 1998. Some of these reefs are in protected waters where no fishing is allowed. The researchers speculated that reefs in waters where no fishing is allowed should recover faster than reefs in water where fishing is allowed. The graph below shows some of the data they collected from three highly protected (unfished) sites and three unprotected (fished) sites to evaluate their hypothesis. 1. By about what percentage did the mean coral cover drop in the protected (unfished) reefs between 1997 and 1999? 2. By about what percentage did the mean coral cover drop in the protected (unfished) reefs between 1997 and 2005? 3. By about what percentage did the coral cover drop in the unprotected (fished) reefs between 1997 and 1999? 4. By about what percentage did the coral cover change in the unprotected (fished) reefs between 1997 and 2005? 5. Do these data support the hypothesis that coral reef recovery should occur faster in areas there fishing is prohibited? Explain. 1. Answer: Dropped from about 28% to 12%. Percent drop = (28-12)/28 x 100 = 6/28 x 100 = 21% drop 2. Answer: Dropped from about 12% to 8%. Percent drop = (12-8)/12 x 100 = 4/12 x 100 = 33% 3. Answer: Dropped from about 26% to 11%. Percent drop = (26-11)/26 x 100 = 5/26 x 100 = 19% drop 4. Answer: They remained about the same with a 11% cover. 5. Answer: These data do not support the hypothesis that the coral reefs in waters where no fishing was allowed should recover faster than reefs in water where fishing is allowed. Solution Manual for Living in the Environment: Principles, Connections, and Solutions G. Tyler Miller, Scott Spoolman 9780538735346