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Name Class CHAPTER 13 Date Exploring the Oceans SECTION 4 Resources from the Ocean BEFORE YOU READ After you read this section, you should be able to answer these questions: • What are the living resources from the ocean? • What are the nonliving resources from the ocean? What Are the Living Resources of the Ocean? People have been harvesting plants and animals from the ocean for thousands of years. Today, harvesting food from the ocean is a multi-billion-dollar industry. As the population of humans on Earth has grown, the demand for these resources has increased. However, the availability of these resources has not increased as much. Harvesting fish from the ocean can harm the environment. Usually, fish can reproduce faster than people can catch them. However, new technology, such as drift nets, has allowed people to catch more fish in less time. This may allow people to take fish faster than they can reproduce. This could cause the population of fish in the oceans to decrease. Also, other animals, such as dolphins and turtles, can be caught in fishing nets. Recently, laws have been passed that control fishing more strictly. These laws are supposed to help reduce the damage fishing can cause to the environment. As a result of these laws, people have begun to raise fish and other types of seafood, such as shellfish and seaweed, in farms near the shore. By growing seafood in these farms, people can conserve and protect wild organisms. STUDY TIP Summarize As you read, make a chart describing the resources that people use from the ocean. Critical Thinking 1. Explain When can fish be considered a renewable resource? When would fish not be considered a renewable resource? New technology, such as these drift nets, allows people to catch more fish in less time. However, other animals, such as dolphins and turtles, can sometimes get caught in the nets. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 249 Exploring the Oceans Name SECTION 4 Class Date Resources from the Ocean continued What Are the Nonliving Resources of the Ocean? Fish and other seafood are important resources that people take from the oceans. However, people also take many nonliving resources from the oceans. These resources include energy resources and material resources. FRESH WATER READING CHECK 2. Define What is desalination? Fresh water is often considered a renewable resource. However, in parts of the world where the climate is dry, fresh water is limited. In these parts of the world, ocean water is desalinated to provide fresh drinking water. Desalination is the process of removing salt from sea water. Most desalination plants heat ocean water to cause the water to evaporate. The water vapor, which is not salty, is collected and condensed into liquid fresh water. Another method of desalination involves passing the ocean water through a membrane to leave the salts behind. However, no matter what process is used, desalination is expensive and can be slow. TIDAL ENERGY Critical Thinking 3. Infer Why can’t tidal energy be used everywhere? The ocean is constantly moving as tides come in and go out. People can use the motion of the water to generate electricity. Energy that is generated from the movement of tides is called tidal energy. Tidal energy is clean, inexpensive, and renewable. However, it can only be used in certain parts of the world. High tide Low tide Gate closed Gate closes TAKE A LOOK 4. Explain Why is tidal energy considered to be renewable? 1 As the tide rises, water enters a bay behind a dam. At high tide, the gate closes to keep the water in the bay. 2 The gate stays closed as the tide goes out. Gate opens 3 At low tide, the gate opens and the water rushes out of the bay. As it moves through the dam, the water turns wheels called turbines that generate electricity. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 250 Exploring the Oceans Name SECTION 4 Class Date Resources from the Ocean continued OIL AND NATURAL GAS Oil and natural gas are considered the most valuable resources in the ocean. Oil and natural gas form from the remains of tiny plants and animals. These remains take millions of years to turn into oil and natural gas. Therefore, oil and gas are nonrenewable resources. Many deposits of oil and natural gas are found in rock near the continental margins. In order to obtain these resources, engineers must drill wells through the rock. About one-fourth of the world’s oil is now obtained from wells in rock beneath the oceans. Oil is refined by manufacturers to make gasoline. Gasoline powers vehicles and generators that make electricity. Oil is also used to make plastic and other products. Say It Discuss In a small group, talk about different ways that you use resources from the ocean every day. READING CHECK 5. List Give two ways that people use oil or natural gas. MINERALS Many different kinds of minerals can be found on the ocean floor. These minerals are commonly in the form of nodules. Nodules are potato-shaped lumps of minerals that form from chemicals dissolved in ocean water. Nodules can be made of many different kinds of minerals. Most nodules contain the element manganese. Manganese can be used to make certain kinds of steel. Some nodules contain the valuable metals iron, copper, nickel, or cobalt. Some contain phosphorus, which can be used in fertilizer. Nodules can be very large. They may contain a large amount of valuable minerals. However, they form in the very deep parts of the ocean. For this reason, they are difficult to mine. READING CHECK 6. Explain Why are nodules hard to mine? Minerals can be found on the ocean floor in the form of nodules. These nodules are difficult to mine because they are found in very deep water. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 251 Exploring the Oceans Name Class Date Section 4 Review SECTION VOCABULARY desalination a process of removing salt from ocean water 1. List Name two living resources from the ocean. 2. Define Write your own definition for desalination. 3. Describe How can the tides be used to generate electricity? 4. Identify Give five minerals that may be found in nodules. 5. List Give four nonliving ocean resources. 6. Infer Why are people starting to farm the oceans instead of harvesting wild organisms? Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 252 Exploring the Oceans Earth Science Answer Key continued 8. It would be flat and uniform, without any Review 1. Plankton are organisms that float and drift mountains or valleys in it. 9. a volcanic mountain on the sea floor 10. where tectonic plates are moving apart 11. An ocean trench is a deep depression in the ocean floor where a tectonic plate subducts. 12. Feature What it is Where it is found Seamount an underwater volcano at plate boundaries or in the middle of a plate Abyssal plain flat part of the ocean basin, covered in sediment in the deep-ocean basins Mid-ocean ridge long, underwater mountain chain where plates move apart Rift valley crack in the crust at a midocean ridge where plates move apart 2. 3. 4. 5. 6. Review 1. Scientists use underwater vessels, sonar, and SECTION 4 RESOURCES FROM THE OCEAN satellite information to study the ocean floor. 2. When plates move together, one plate sinks beneath another. This produces a large, deep trench in the ocean floor. 3. Some comes from the land. Some is made of the remains of sea creatures that settle to the bottom when the creatures die. 4. Tectonic plates move apart, creating tension. Cracks form in the crust. Melted rock rises through the cracks, cools, and hardens. The hardened rock forms the ridge. 1. Fish are a renewable resource because they 2. 3. 4. 5. 6. can usually reproduce faster than we hunt them. If we hunt them too quickly, they are a nonrenewable resource. removing salt from sea water Most places are not close enough to the ocean to use tidal power. the tides cannot be used up for energy and to make plastics They form deep underwater. Review 1. fish, seaweed 2. Desalination is a method people use to make SECTION 3 LIFE IN THE OCEAN 1. plankton, nekton, benthos 2. the ocean floor, the area near it, and the 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. freely near the ocean surface. Nekton are organisms that actively swim in the open ocean. The benthic environment is found at the bottom of the ocean. It includes the animals living near, on, or in the ocean floor. The pelagic environment is found near the ocean surface and in the open and deep-ocean water. It gets more sunlight than any other zone, so many phytoplankton can grow. These phytoplankton act as food for other marine organisms in this zone. No sunlight reaches these zones. Sometimes the zone is underwater, and sometimes it is not. The organisms in this zone must be able to survive dry and wet conditions, as well as crashing waves. neritic zone, oceanic zone organisms that live there between the low-tide and high-tide limits They attach themselves to rocks. about 645 ft The sublittoral zone is always underwater. The animals eat other animals for food. the abyssal plain a hot-water vent in the ocean floor in ocean trenches the water above the benthic environment above the continental shelf oceanic zone 3. 4. 5. 6. fresh water from ocean water. Water enters a bay behind a dam as the tide rises. When high tide reaches its peak, the gate closes. The gate remains closed as the tide falls. The gate opens at low tide, and water rushes through the dam. This moves the turbines to generate electricity. iron, copper, manganese, phosphorus, nickel water, minerals, oil, tides People consume more fish than can be harvested from the oceans without causing fish to become too scarce. By farming the fish, people ensure a supply of fish without reducing wild populations too much. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook Answer Key 51 Earth Science