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Aquatic Ecology Notes. Chapter Overview Questions What are the basic types of aquatic life zones and what factors influence the kinds of life they contain?

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Presentation on theme: "Aquatic Ecology Notes. Chapter Overview Questions What are the basic types of aquatic life zones and what factors influence the kinds of life they contain?"— Presentation transcript:

1 Aquatic Ecology Notes

2 Chapter Overview Questions What are the basic types of aquatic life zones and what factors influence the kinds of life they contain? What are the basic types of aquatic life zones and what factors influence the kinds of life they contain? What are the major types of freshwater life zones, and how do human activities affect them? What are the major types of freshwater life zones, and how do human activities affect them?

3 Chapter Overview Questions What do we know about aquatic biodiversity, and what is its economic and ecological importance? What do we know about aquatic biodiversity, and what is its economic and ecological importance? How are human activities affecting aquatic biodiversity? How are human activities affecting aquatic biodiversity? How can we manage and sustain the world’s marine fisheries? How can we manage and sustain the world’s marine fisheries?

4 Chapter Overview Questions (cont’d) How can we protect, sustain, and restore wetlands? How can we protect, sustain, and restore wetlands? How can we protect, sustain, and restore lakes, rivers, and freshwater fisheries? How can we protect, sustain, and restore lakes, rivers, and freshwater fisheries?

5 Chapter Overview Questions Why is water so important, how much freshwater is available to us, and how much of it are we using? Why is water so important, how much freshwater is available to us, and how much of it are we using? What causes freshwater shortages, and what can be done about this problem? What causes freshwater shortages, and what can be done about this problem? What are the advantages and disadvantages of withdrawing groundwater? What are the advantages and disadvantages of withdrawing groundwater? What are the advantages and disadvantages of using dams and reservoirs to supply more water? What are the advantages and disadvantages of using dams and reservoirs to supply more water?

6 Chapter Overview Questions (cont’d) What are the advantages and disadvantages of transferring large amounts of water from one place to another? What are the advantages and disadvantages of transferring large amounts of water from one place to another? Can removing salt from seawater solve our water supply problems? Can removing salt from seawater solve our water supply problems? How can we waste less water? How can we waste less water? How can we use the earth’s water more sustainably? How can we use the earth’s water more sustainably? What causes flooding, and what can we do about it? What causes flooding, and what can we do about it?

7 WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL Water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes and pollutants, and moves continually through the hydrologic cycle. Water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes and pollutants, and moves continually through the hydrologic cycle. Only about 0.02% of the earth’s water supply is available to us as liquid freshwater. Only about 0.02% of the earth’s water supply is available to us as liquid freshwater.

8 WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL Comparison of population sizes and shares of the world’s freshwater among the continents. Comparison of population sizes and shares of the world’s freshwater among the continents. Figure 14-2

9 WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL Some precipitation infiltrates the ground and is stored in soil and rock (groundwater). Some precipitation infiltrates the ground and is stored in soil and rock (groundwater). Water that does not sink into the ground or evaporate into the air runs off (surface runoff) into bodies of water. Water that does not sink into the ground or evaporate into the air runs off (surface runoff) into bodies of water. The land from which the surface water drains into a body of water is called its watershed or drainage basin. The land from which the surface water drains into a body of water is called its watershed or drainage basin.

10 Fig. 14-3, p. 308 Unconfined Aquifer Recharge Area Precipitation Evaporation and transpirationEvaporation Confined Recharge Area Runoff Flowing artesian well Recharge Unconfined Aquifer Stream Well requiring a pump Infiltration Water table Lake Infiltration Unconfined aquifer Confined aquifer Confining impermeable rock layer Less permeable material such as clay

11 WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL We currently use more than half of the world’s reliable runoff of surface water and could be using 70-90% by 2025. We currently use more than half of the world’s reliable runoff of surface water and could be using 70-90% by 2025. About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources. About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources. Irrigation is the biggest user of water (70%), followed by industries (20%) and cities and residences (10%). Irrigation is the biggest user of water (70%), followed by industries (20%) and cities and residences (10%).

12 Salinity The saltiness. The saltiness.

13 Niches

14 What Kinds of Organisms Live in Aquatic Life Zones? Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms. Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms. Plankton: important group of weakly swimming, free-floating biota. Plankton: important group of weakly swimming, free-floating biota. Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria) Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria) Necton: fish, turtles, whales. Necton: fish, turtles, whales. Benthos: bottom dwellers (barnacles, oysters). Benthos: bottom dwellers (barnacles, oysters). Decomposers: breakdown organic compounds (mostly bacteria). Decomposers: breakdown organic compounds (mostly bacteria).

15 Phytoplankton Description – small drifting plants Description – small drifting plants Niche – they are producers that support most aquatic food chains Niche – they are producers that support most aquatic food chains Example – cyanobacteria & many types of algae Example – cyanobacteria & many types of algae

16 Zooplankton Description – herbivores that feed on phytoplankton or other zooplankton Description – herbivores that feed on phytoplankton or other zooplankton Niche – food stock for larger consumers Niche – food stock for larger consumers Example – krill; small crustaceans Example – krill; small crustaceans

17 Nekton Description – larger, strong- swimming consumers Description – larger, strong- swimming consumers Niche – top consumers in the aquatic ecosystem Niche – top consumers in the aquatic ecosystem Example – fish, turtles, and whales Example – fish, turtles, and whales

18 Benthos Description – bottom-dwelling creatures Description – bottom-dwelling creatures Niche – primary consumers, decomposers Niche – primary consumers, decomposers Example – barnacles, oysters, and lobsters Example – barnacles, oysters, and lobsters

19 Freshwater Ecosystems

20 FRESHWATER LIFE ZONES Freshwater life zones include: Freshwater life zones include: Standing (lentic) water such as lakes, ponds, and inland wetlands. Standing (lentic) water such as lakes, ponds, and inland wetlands. Flowing (lotic) systems such as streams and rivers. Flowing (lotic) systems such as streams and rivers. Figure 6-14

21 Flowing Water Ecosystems Because of different environmental conditions in each zone, a river is a system of different ecosystems.

22 Fig. 12-11, p. 267 Deliver nutrients to sea to help sustain coastal fisheries Deposit silt that maintains deltas Purify water Renew and renourish wetlands Provide habitats for wildlife Natural Capital Ecological Services of Rivers

23 Freshwater Streams and Rivers: From the Mountains to the Oceans Water flowing from mountains to the sea creates different aquatic conditions and habitats. Water flowing from mountains to the sea creates different aquatic conditions and habitats. Figure 6-17

24 Headwater Stream Characteristics A narrow zone of cold, clear water that rushes over waterfalls and rapids. Large amounts of oxygen are present. Fish are also present. Ex. trout. A narrow zone of cold, clear water that rushes over waterfalls and rapids. Large amounts of oxygen are present. Fish are also present. Ex. trout.

25 Downstream Characteristics Slower-moving water, less oxygen, warmer temperatures, and lots of algae and cyanobacteria. Slower-moving water, less oxygen, warmer temperatures, and lots of algae and cyanobacteria.

26 Energy Source Gravity Gravity

27 Standing Water Ecosystems Lakes, ponds, etc.

28 Life in Layers Life in most aquatic systems is found in surface, middle, and bottom layers. Life in most aquatic systems is found in surface, middle, and bottom layers. Temperature, access to sunlight for photosynthesis, dissolved oxygen content, nutrient availability changes with depth. Temperature, access to sunlight for photosynthesis, dissolved oxygen content, nutrient availability changes with depth. Euphotic zone (upper layer in deep water habitats): sunlight can penetrate. Euphotic zone (upper layer in deep water habitats): sunlight can penetrate.

29 Lakes: Water-Filled Depressions Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, and groundwater seepage consisting of: Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, and groundwater seepage consisting of: Littoral zone (near shore, shallow, with rooted plants). Littoral zone (near shore, shallow, with rooted plants). Limnetic zone (open, offshore area, sunlit). Limnetic zone (open, offshore area, sunlit). Profundal zone (deep, open water, too dark for photosynthesis). Profundal zone (deep, open water, too dark for photosynthesis). Benthic zone (bottom of lake, nourished by dead matter). Benthic zone (bottom of lake, nourished by dead matter).

30 Littoral Zone A shallow area near the shore, to the depth at which rooted plants stop growing. Ex. frogs, snails, insects, fish, cattails, and water lilies. A shallow area near the shore, to the depth at which rooted plants stop growing. Ex. frogs, snails, insects, fish, cattails, and water lilies.

31 Limnetic Zone Open, sunlit water that extends to the depth penetrated by sunlight. Open, sunlit water that extends to the depth penetrated by sunlight.

32 Profundal Zone Deep, open water where it is too dark for photosynthesis. Deep, open water where it is too dark for photosynthesis.

33 Thermal Stratification

34 Lakes: Water-Filled Depressions Figure 6-15

35 Definition The temperature difference in deep lakes where there are warm summers and cold winters. The temperature difference in deep lakes where there are warm summers and cold winters.

36 Lakes: Water-Filled Depressions During summer and winter in deep temperate zone lakes the become stratified into temperature layers and will overturn. During summer and winter in deep temperate zone lakes the become stratified into temperature layers and will overturn. This equalizes the temperature at all depths. This equalizes the temperature at all depths. Oxygen is brought from the surface to the lake bottom and nutrients from the bottom are brought to the top. Oxygen is brought from the surface to the lake bottom and nutrients from the bottom are brought to the top.

37 Causes During the summer, lakes become stratified into different temperature layers that resist mixing because summer sunlight warms surface waters, making them less dense. During the summer, lakes become stratified into different temperature layers that resist mixing because summer sunlight warms surface waters, making them less dense.

38 Thermocline The middle layer that acts as a barrier to the transfer of nutrients and dissolved oxygen. The middle layer that acts as a barrier to the transfer of nutrients and dissolved oxygen.

39 Fall Turnover As the temperatures begin to drop, the surface layer becomes more dense, and it sinks to the bottom. This mixing brings nutrients from the bottom up to the surface and sends oxygen to the bottom. As the temperatures begin to drop, the surface layer becomes more dense, and it sinks to the bottom. This mixing brings nutrients from the bottom up to the surface and sends oxygen to the bottom.

40 Spring Turnover As top water warms and ice melts, it sinks through and below the cooler, less dense water, sending oxygen down and nutrients up. As top water warms and ice melts, it sinks through and below the cooler, less dense water, sending oxygen down and nutrients up.

41 Freshwater Wetlands

42 Freshwater Inland Wetlands: Vital Sponges Inland wetlands act like natural sponges that absorb and store excess water from storms and provide a variety of wildlife habitats. Inland wetlands act like natural sponges that absorb and store excess water from storms and provide a variety of wildlife habitats. Figure 6-18

43 Freshwater Inland Wetlands: Vital Sponges Filter and degrade pollutants. Filter and degrade pollutants. Reduce flooding and erosion by absorbing slowly releasing overflows. Reduce flooding and erosion by absorbing slowly releasing overflows. Help replenish stream flows during dry periods. Help replenish stream flows during dry periods. Help recharge ground aquifers. Help recharge ground aquifers. Provide economic resources and recreation. Provide economic resources and recreation.

44 Marshes An area of temporarily flooded, often silty land beside a river or lake. An area of temporarily flooded, often silty land beside a river or lake.

45 Swamps A lowland region permanently covered with water. A lowland region permanently covered with water.

46 Hardwood Bottomland Forest An area down by a river or stream where lots of hardwoods, like oaks, grow. An area down by a river or stream where lots of hardwoods, like oaks, grow.

47 Prairie Potholes These are depressions that hold water out on the prairie, especially up north in Canada. It is a very good duck habitat. These are depressions that hold water out on the prairie, especially up north in Canada. It is a very good duck habitat.

48 Peat Moss Bog A wet area that over time fills in (the last stage of succession is peat moss). It can be very deep. In Ireland, they burn this for wood. A wet area that over time fills in (the last stage of succession is peat moss). It can be very deep. In Ireland, they burn this for wood.

49 Importance of freshwater wetlands They filter & purify water. They filter & purify water. Habitat for many animals and plants. Habitat for many animals and plants.

50 Historical Aspects Developers and farmers want Congress to revise the definition of wetlands. This would make 60-75% of all wetlands unavailable for protection. The Audubon Society estimates that wetlands provide water quality protection worth $1.6 billion per year, and they say if that wetlands are destroyed, the U.S. would spend $7.7 billion to $31 billion per year in additional flood-control costs. Developers and farmers want Congress to revise the definition of wetlands. This would make 60-75% of all wetlands unavailable for protection. The Audubon Society estimates that wetlands provide water quality protection worth $1.6 billion per year, and they say if that wetlands are destroyed, the U.S. would spend $7.7 billion to $31 billion per year in additional flood-control costs.

51 Estuaries

52 Definition A partially enclosed area of coastal water where sea water mixes with freshwater. A partially enclosed area of coastal water where sea water mixes with freshwater.

53 Salt Marshes The ground here is saturated with water and there is little oxygen, so decay takes place slowly. It has a surface inlet and outlet, and contains many invertebrates. It is also the breeding ground for many ocean animals. Ex. crabs and shellfish. The ground here is saturated with water and there is little oxygen, so decay takes place slowly. It has a surface inlet and outlet, and contains many invertebrates. It is also the breeding ground for many ocean animals. Ex. crabs and shellfish.

54 Mangrove Forests These are along warm, tropical coasts where there is too much silt for coral reefs to grow. It is dominated by salt- tolerant trees called mangroves (55 different species exist). It also helps to protect the coastline from erosion and provides a breeding nursery for some 2000 species of fish, invertebrates, and plants. These are along warm, tropical coasts where there is too much silt for coral reefs to grow. It is dominated by salt- tolerant trees called mangroves (55 different species exist). It also helps to protect the coastline from erosion and provides a breeding nursery for some 2000 species of fish, invertebrates, and plants.

55 Importance of Estuaries Just one acre of estuary provides $75,000 worth of free waste treatment, and has a value of about $83,000 when recreation and fish for food are included. Just one acre of estuary provides $75,000 worth of free waste treatment, and has a value of about $83,000 when recreation and fish for food are included. Prime Kansas farmland has a top value of $1,200 and an annual production value of $600. Prime Kansas farmland has a top value of $1,200 and an annual production value of $600.

56 The Everglades Southern Florida to the Keys

57 Case Study: Restoring the Florida Everglades The world’s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. The world’s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. 90% of park’s wading birds have vanished. 90% of park’s wading birds have vanished. Other vertebrate populations down 75-95%. Other vertebrate populations down 75-95%. Large volumes of water that once flowed through the park have been diverted for crops and cities. Large volumes of water that once flowed through the park have been diverted for crops and cities. Runoff has caused noxious algal blooms. Runoff has caused noxious algal blooms.

58 Problems As Miami develops, it encroaches on everglades. Plus, it prompts people vs. wildlife. It is freshwater and local areas are draining it. As Miami develops, it encroaches on everglades. Plus, it prompts people vs. wildlife. It is freshwater and local areas are draining it.

59 Restoring the Florida Everglades The project has been attempting to restore the Everglades and Florida water supplies. The project has been attempting to restore the Everglades and Florida water supplies. Figure 12-10

60 Restoration Build huge aqueduct, or find other sources of fresh water an protect it federally under endangered species act, etc. Build huge aqueduct, or find other sources of fresh water an protect it federally under endangered species act, etc.

61 The Water Resource

62 Importance Leonardo da Vinci said that “Water is the driver of nature.” Without water, the other nutrient cycles would not exist in their present forms, and current forms of life on earth could not exist. Leonardo da Vinci said that “Water is the driver of nature.” Without water, the other nutrient cycles would not exist in their present forms, and current forms of life on earth could not exist.

63 Hydrogen Bonds

64 Attraction Between Molecules The strong forces of attraction between molecules of water. The strong forces of attraction between molecules of water.

65 Heat Capacity Water changes temp very slowly because it can store heat. This protects living organisms from the shock of abrupt temperature changes. Water changes temp very slowly because it can store heat. This protects living organisms from the shock of abrupt temperature changes.

66 Heat of Vaporization The temperature at which water turns to vapor. The temperature at which water turns to vapor.

67 Universal Solvent Water can dissolve a wide variety of compounds. This means it can easily become polluted by water-soluble wastes. Water can dissolve a wide variety of compounds. This means it can easily become polluted by water-soluble wastes.

68 Expansion When Frozen Ice has a lower density than liquid water. Thus, ice floats on water. Ice has a lower density than liquid water. Thus, ice floats on water.

69 Hydrologic Cycle

70 Surface Water Examples – streams, rivers, and lakes Examples – streams, rivers, and lakes Source – precipitation Source – precipitation Watershed – Ex. small streams  larger streams  rivers  sea Watershed – Ex. small streams  larger streams  rivers  sea

71 Groundwater Aquifers–porous rock w/ water flowing through Aquifers–porous rock w/ water flowing through Water Table – the level of earth’s land crust to which the aquifer is filled Water Table – the level of earth’s land crust to which the aquifer is filled Renewability – the circulation rate of groundwater is slow (300 to 4,600 years). Renewability – the circulation rate of groundwater is slow (300 to 4,600 years).

72 Water Usage Irrigation – watering crops Irrigation – watering crops Industry – coolant (power plant) Industry – coolant (power plant) Domestic and Municipal – drinking, sewage, bathwater, dishwater & laundry Domestic and Municipal – drinking, sewage, bathwater, dishwater & laundry

73 Problems

74 Too Much Water Problems include flooding, pollution of water supply, and sewage seeping into the ground. Problems include flooding, pollution of water supply, and sewage seeping into the ground.

75 TOO MUCH WATER Heavy rainfall, rapid snowmelt, removal of vegetation, and destruction of wetlands cause flooding. Heavy rainfall, rapid snowmelt, removal of vegetation, and destruction of wetlands cause flooding. Floodplains, which usually include highly productive wetlands, help provide natural flood and erosion control, maintain high water quality, and recharge groundwater. Floodplains, which usually include highly productive wetlands, help provide natural flood and erosion control, maintain high water quality, and recharge groundwater. To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water. To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water.

76 TOO MUCH WATER Comparison of St. Louis, Missouri under normal conditions (1988) and after severe flooding (1993). Comparison of St. Louis, Missouri under normal conditions (1988) and after severe flooding (1993). Figure 14-22

77 TOO MUCH WATER Human activities have contributed to flood deaths and damages. Human activities have contributed to flood deaths and damages. Figure 14-23

78 Fig. 14-23a, p. 330 Oxygen released by vegetation Diverse ecological habitat Evapotranspiration Trees reduce soil erosion from heavy rain and wind Agricultural land Steady river flow Leaf litter improves soil fertility Tree roots stabilize soil and aid water flow Vegetation releases water slowly and reduces flooding Forested Hillside

79 Fig. 14-23b, p. 330 Tree plantation Roads destabilize hillsides Evapotranspiration decreases Ranching accelerates soil erosion by water and wind Winds remove fragile topsoil Agricultural land is flooded and silted up Gullies and landslides Heavy rain leaches nutrients from soil and erodes topsoil Silt from erosion blocks rivers and reservoirs and causes flooding downstream Rapid runoff causes flooding After Deforestation

80 Too Little Water

81 Examples Examples include drought and expanding deserts. Examples include drought and expanding deserts.

82 Overdrawing Surface Water Lake levels drop, recreation use drops, fisheries drop, and salinization occurs. Ex. Soviet Union (Aral Sea); the inland sea drained the river that fed into it. Now it’s a huge disaster (read pg. 305 in text). Lake levels drop, recreation use drops, fisheries drop, and salinization occurs. Ex. Soviet Union (Aral Sea); the inland sea drained the river that fed into it. Now it’s a huge disaster (read pg. 305 in text). 1964 1997

83 Case Study: The Aral Sea Disaster Diverting water from the Aral Sea and its two feeder rivers mostly for irrigation has created a major ecological, economic, and health disaster. Diverting water from the Aral Sea and its two feeder rivers mostly for irrigation has created a major ecological, economic, and health disaster. About 85% of the wetlands have been eliminated and roughly 50% of the local bird and mammal species have disappeared. About 85% of the wetlands have been eliminated and roughly 50% of the local bird and mammal species have disappeared. Since 1961, the sea’s salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct. Since 1961, the sea’s salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct.

84 Aquifer Depletion This harms endangered species, and salt water can seep in. This harms endangered species, and salt water can seep in.

85 Salinization of Irrigated Soil Water is poured onto soil and evaporates. Over time, as this is repeated, nothing will grow there anymore. Water is poured onto soil and evaporates. Over time, as this is repeated, nothing will grow there anymore.

86 U.S. Water Problems

87 Surface Water Problems The polluted Mississippi River (non-source point pollution) has too much phosphorus. The polluted Mississippi River (non-source point pollution) has too much phosphorus. In the Eerie Canal, which connects the ocean to the Great Lakes, lampreys came in and depleted the fish. The zebra mollusk is also a problem in the Great Lakes. In the Eerie Canal, which connects the ocean to the Great Lakes, lampreys came in and depleted the fish. The zebra mollusk is also a problem in the Great Lakes.

88 Effects of Plant Nutrients on Lakes: Too Much of a Good Thing Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. Figure 6-16

89 Effects of Plant Nutrients on Lakes: Too Much of a Good Thing Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. Oligotrophic (poorly nourished) lake: Usually newly formed lake with small supply of plant nutrient input. Oligotrophic (poorly nourished) lake: Usually newly formed lake with small supply of plant nutrient input. Eutrophic (well nourished) lake: Over time, sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant growth. Eutrophic (well nourished) lake: Over time, sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant growth.

90 Effects of Plant Nutrients on Lakes: Too Much of a Good Thing Cultural eutrophication: Cultural eutrophication: Human inputs of nutrients from the atmosphere and urban and agricultural areas can accelerate the eutrophication process. Human inputs of nutrients from the atmosphere and urban and agricultural areas can accelerate the eutrophication process.

91 Mono Lake (like the Dead Sea) This has a huge salt concentration due to man’s draining. (like the Dead Sea) This has a huge salt concentration due to man’s draining.

92 Colorado River Basin These are dams & reservoirs that feed from the Colorado River all the way to San Diego, LA, Palm Springs, Phoenix & Mexico. So far has worked because they haven’t withdrawn their full allocations. See pg306. These are dams & reservoirs that feed from the Colorado River all the way to San Diego, LA, Palm Springs, Phoenix & Mexico. So far has worked because they haven’t withdrawn their full allocations. See pg306.

93 The Colorado River Basin The area drained by this basin is equal to more than one- twelfth of the land area of the lower 48 states. The area drained by this basin is equal to more than one- twelfth of the land area of the lower 48 states. Figure 14-14

94 Fig. 14-14, p. 318 Dam Aqueduct or canal Upper Basin LOWER BASIN 0100 mi. 0150 km Lower Basin UPPER BASIN IDAHO WYOMING Salt Lake City Grand Junction Denver UTAH NEVADA COLORADO Lake Powell Las Vegas Grand Canyon Glen Canyon Dam Boulder City NEW MEXICO ARIZONA Los Angeles Albuquerque Phoenix San Diego Mexicali Yuma Tucson All-American Canal Gulf of California MEXICO CALIFORNIA Palm Springs Colorado River

95 Case Study: The Colorado Basin – an Overtapped Resource The Colorado River has so many dams and withdrawals that it often does not reach the ocean. The Colorado River has so many dams and withdrawals that it often does not reach the ocean. 14 major dams and reservoirs, and canals. 14 major dams and reservoirs, and canals. Water is mostly used in desert area of the U.S. Water is mostly used in desert area of the U.S. Provides electricity from hydroelectric plants for 30 million people (1/10 th of the U.S. population). Provides electricity from hydroelectric plants for 30 million people (1/10 th of the U.S. population).

96 Case Study: The Colorado Basin – an Overtapped Resource Lake Powell, is the second largest reservoir in the U.S. Lake Powell, is the second largest reservoir in the U.S. It hosts one of the hydroelectric plants located on the Colorado River. It hosts one of the hydroelectric plants located on the Colorado River. Figure 14-15

97 Groundwater Problems These include pollution, salt, and draining too much. These include pollution, salt, and draining too much.

98 Other Effects of Groundwater Overpumping Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater. Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater. Figure 14-10

99 Groundwater Depletion: A Growing Problem The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest). The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest). Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S. Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S. Figure 14-8

100 Ogallala Aquifer This is the world’s largest known aquifer, and fuels agricultural regions in the U.S. It extends from South Dakota to Texas. It’s essentially a non-renewable aquifer from the last ice age with an extremely slow recharge rate. In some cases, water is pumped out 8 to 10 times faster than it is renewed. Northern states will still have ample supplies, but for the south it’s getting thinner. It is estimated that ¼ of the aquifer will be depleted by 2020. This is the world’s largest known aquifer, and fuels agricultural regions in the U.S. It extends from South Dakota to Texas. It’s essentially a non-renewable aquifer from the last ice age with an extremely slow recharge rate. In some cases, water is pumped out 8 to 10 times faster than it is renewed. Northern states will still have ample supplies, but for the south it’s getting thinner. It is estimated that ¼ of the aquifer will be depleted by 2020.

101 Global Water Problems

102 Impacts of Human Activities on Freshwater Systems Dams, cities, farmlands, and filled-in wetlands alter and degrade freshwater habitats. Dams, cities, farmlands, and filled-in wetlands alter and degrade freshwater habitats. Dams, diversions and canals have fragmented about 40% of the world’s 237 large rivers. Dams, diversions and canals have fragmented about 40% of the world’s 237 large rivers. Flood control levees and dikes alter and destroy aquatic habitats. Flood control levees and dikes alter and destroy aquatic habitats. Cities and farmlands add pollutants and excess plant nutrients to streams and rivers. Cities and farmlands add pollutants and excess plant nutrients to streams and rivers. Many inland wetlands have been drained or filled for agriculture or (sub)urban development. Many inland wetlands have been drained or filled for agriculture or (sub)urban development.

103 Core Case Study: A Biological Roller Coaster Ride in Lake Victoria Lake Victoria has lost their endemic fish species to large introduced predatory fish. Lake Victoria has lost their endemic fish species to large introduced predatory fish. Figure 12-1

104 Core Case Study: A Biological Roller Coaster Ride in Lake Victoria Reasons for Lake Victoria’s loss of biodiversity: Reasons for Lake Victoria’s loss of biodiversity: Introduction of Nile perch. Introduction of Nile perch. Lake experienced algal blooms from nutrient runoff. Lake experienced algal blooms from nutrient runoff. Invasion of water hyacinth has blocked sunlight and deprived oxygen. Invasion of water hyacinth has blocked sunlight and deprived oxygen. Nile perch is in decline because it has eaten its own food supply. Nile perch is in decline because it has eaten its own food supply.

105 Stable Runoff As water runs off from rain, it’s supposed to get into rivers, and finally off to the sea. But when we dam rivers, less goes to the ocean, meaning the brackish water (where the river hits the ocean) becomes more salty. This is the breeding ground for many fish and invertebrates. This harms the ecology of the area. As water runs off from rain, it’s supposed to get into rivers, and finally off to the sea. But when we dam rivers, less goes to the ocean, meaning the brackish water (where the river hits the ocean) becomes more salty. This is the breeding ground for many fish and invertebrates. This harms the ecology of the area.

106 Drinking Water Problems

107 Coliform Bacteria The W.H.O. recommends there be zero colonies of bacteria per 100ml of drinking water and 200 colonies per 100ml of swimming water. The average human excretes 2 billion organisms per day (see how easily untreated sewage can contaminate water?). The W.H.O. recommends there be zero colonies of bacteria per 100ml of drinking water and 200 colonies per 100ml of swimming water. The average human excretes 2 billion organisms per day (see how easily untreated sewage can contaminate water?).

108 Oxygen Demanding Wastes These are organic wastes that can be decomposed by aerobic bacteria (causes lack of oxygen). Fish die as a result of a lack of oxygen. These are organic wastes that can be decomposed by aerobic bacteria (causes lack of oxygen). Fish die as a result of a lack of oxygen.

109 Water-Soluble Inorganic Chemicals These include acids, salts, mercury, and lead. They make water unfit to drink. These include acids, salts, mercury, and lead. They make water unfit to drink.

110 Organic Material These include oil, gas, plastics, pesticides, and detergents. These include oil, gas, plastics, pesticides, and detergents.

111 Population Growth Problems include over-drawing fresh water, pollution, and over- building so that water can’t seep into the ground. Problems include over-drawing fresh water, pollution, and over- building so that water can’t seep into the ground.

112 Sharing Water Resources There are water wars out west. California bought the water from the Colorado River, but Arizona wants it. Who owns it? The same thing is happening in Texas. More water rights are sold than the actual amount of water. How do you share water? This is a problem all over the world. There are water wars out west. California bought the water from the Colorado River, but Arizona wants it. Who owns it? The same thing is happening in Texas. More water rights are sold than the actual amount of water. How do you share water? This is a problem all over the world.

113 Water Management

114 Dams and Reservoirs Description: A dammed stream that can capture & store water from rain & melted snow. Benefits: Hydroelectric power; provides water to towns; recreation; controls floods downstream Problems: Reduces downstream flow; prevents water from reaching the sea (Colorado River) devastates fish life; reduces biodiversity.

115 USING DAMS AND RESERVOIRS TO SUPPLY MORE WATER Large dams and reservoirs can produce cheap electricity, reduce downstream flooding, and provide year-round water for irrigating cropland, but they also displace people and disrupt aquatic systems. Large dams and reservoirs can produce cheap electricity, reduce downstream flooding, and provide year-round water for irrigating cropland, but they also displace people and disrupt aquatic systems.

116 Fig. 14-13a, p. 317 Provides water for year-round irrigation of cropland Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Provides water for drinking Downstream cropland and estuaries are deprived of nutrient-rich silt Reservoir is useful for recreation and fishing Risk of failure and devastating downstream flooding Can produce cheap electricity (hydropower) Downstream flooding is reduced Migration and spawning of some fish are disrupted

117 Fig. 14-13b, p. 317 Powerlines Reservoir Dam Powerhouse Intake Turbine

118 Case Study: China’s Three Gorges Dam There is a debate over whether the advantages of the world’s largest dam and reservoir will outweigh its disadvantages. There is a debate over whether the advantages of the world’s largest dam and reservoir will outweigh its disadvantages. The dam will be 2 kilometers long. The dam will be 2 kilometers long. The electric output will be that of 18 large coal- burning or nuclear power plants. The electric output will be that of 18 large coal- burning or nuclear power plants. It will facilitate ship travel reducing transportation costs. It will facilitate ship travel reducing transportation costs. Dam will displace 1.2 million people. Dam will displace 1.2 million people. Dam is built over seismatic fault and already has small cracks. Dam is built over seismatic fault and already has small cracks.

119 Dam Removal Some dams are being removed for ecological reasons and because they have outlived their usefulness. Some dams are being removed for ecological reasons and because they have outlived their usefulness. In 1998 the U.S. Army Corps of Engineers announced that it would no longer build large dams and diversion projects in the U.S. In 1998 the U.S. Army Corps of Engineers announced that it would no longer build large dams and diversion projects in the U.S. The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams. The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams. Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment. Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment.

120 Water Diversion Description: Damming a river to control where the water flows Benefits: Keeps water where we want it- cities! Problems: Drains wetlands, destroys land

121 Desalinization Description: Removing salt from salt water Benefits: Freshwater Problems: Uses lots of energy; costs 3-5X’s more money; what do we do with the salt?

122 DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS AND GIANT BAGGIES Removing salt from seawater by current methods is expensive and produces large amounts of salty wastewater that must be disposed of safely. Removing salt from seawater by current methods is expensive and produces large amounts of salty wastewater that must be disposed of safely. Distillation: heating saltwater until it evaporates, leaves behind water in solid form. Distillation: heating saltwater until it evaporates, leaves behind water in solid form. Reverse osmosis: uses high pressure to force saltwater through a membrane filter. Reverse osmosis: uses high pressure to force saltwater through a membrane filter.

123 DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS AND GIANT BAGGIES Seeding clouds with tiny particles of chemicals to increase rainfall towing icebergs or huge bags filled with freshwater to dry coastal areas have all been proposed but are unlikely to provide significant amounts of freshwater. Seeding clouds with tiny particles of chemicals to increase rainfall towing icebergs or huge bags filled with freshwater to dry coastal areas have all been proposed but are unlikely to provide significant amounts of freshwater.

124 Harvesting Icebergs Description: Towing massive icebergs to arid coastal areas (S. California; Saudi Arabia) Benefits: freshwater Problems: Technology not available; costs too high; raise temperatures around the earth.

125 INCREASING WATER SUPPLIES BY WASTING LESS WATER Sixty percent of the world’s irrigation water is currently wasted, but improved irrigation techniques could cut this waste to 5-20%. Sixty percent of the world’s irrigation water is currently wasted, but improved irrigation techniques could cut this waste to 5-20%. Center-pivot, low pressure sprinklers sprays water directly onto crop. Center-pivot, low pressure sprinklers sprays water directly onto crop. It allows 80% of water to reach crop. It allows 80% of water to reach crop. Has reduced depletion of Ogallala aquifer in Texas High Plains by 30%. Has reduced depletion of Ogallala aquifer in Texas High Plains by 30%.

126 Fig. 14-18, p. 325 Center pivot Drip irrigation Gravity flow (efficiency 60% and 80% with surge valves) Above- or below- ground pipes or tubes deliver water to individual plant roots. Water usually comes from an aqueduct system or a nearby river. (efficiency 90–95%) (efficiency 80%–95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers.

127 Conservation Description: Saving the water we have Methods: recycling; conserving at home; xeriscaping; fix leaks Benefits: Saves money; Saves Wildlife Problems: bothersome to people; lack of caring; laziness

128 Fishing Problems & Techniques The major decline in the worldwide catch of fish since 1990 is because of over-fishing. The major decline in the worldwide catch of fish since 1990 is because of over-fishing. By-catch- fish or animals that were not meant to be caught. By-catch- fish or animals that were not meant to be caught.

129 Overfishing and Extinction: Gone Fishing, Fish Gone About 75% of the world’s commercially valuable marine fish species are over fished or fished near their sustainable limits. About 75% of the world’s commercially valuable marine fish species are over fished or fished near their sustainable limits. Big fish are becoming scarce. Big fish are becoming scarce. Smaller fish are next. Smaller fish are next. We throw away 30% of the fish we catch. We throw away 30% of the fish we catch. We needlessly kill sea mammals and birds. We needlessly kill sea mammals and birds.

130 Fig. 12-A, p. 255 Fish farming in cage Trawler fishing Spotter airplane Sonar Trawl flap Trawl lines Purse-seine fishing Trawl bag Fish school Drift-net fishing Long line fishing Lines with hooks Fish caught by gills Deep sea aquaculture cage Float Buoy

131 Purse Seines

132 A large purse-like net is put into the ocean and is then closed like a drawstring purse to trap the fish. A large purse-like net is put into the ocean and is then closed like a drawstring purse to trap the fish. Tuna is a fish typically caught in purse seines Tuna is a fish typically caught in purse seines Dolphins are a by-catch of purse seines Dolphins are a by-catch of purse seines

133 Long-line fishing Lines are put out that can be up to 80 miles long w/ thousands of baited hooks on them. These are left out free- floating for days and then the boat comes back and picks them up. Lines are put out that can be up to 80 miles long w/ thousands of baited hooks on them. These are left out free- floating for days and then the boat comes back and picks them up. Pilot whales, dolphins, sea turtles, and birds are by-catch of this technique. Pilot whales, dolphins, sea turtles, and birds are by-catch of this technique.

134 Drift-net fishing Each net hangs as much as 50 feet below the surface and up to 34 miles long. Each net hangs as much as 50 feet below the surface and up to 34 miles long. Anything that comes into contact w/ these nearly invisible nets are entangled. Anything that comes into contact w/ these nearly invisible nets are entangled. This leads to overfishing This leads to overfishing Many unwanted fish and marine mammals, turtles and seabirds are caught. Many unwanted fish and marine mammals, turtles and seabirds are caught.

135 HUMAN IMPACTS ON AQUATIC BIODIVERSITY Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Figure 12-2

136 Population Growth and Pollution Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Figure 12-3


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