TEKS 5



TEKS Lesson 8.11D: Human Dependence on Ocean Systems

Why do humans depend on ocean systems?

Oceans cover more than two-thirds of Earth. Humans depend on oceans because they control a wide variety of Earth systems. For example, they regulate heat flow around the planet, which in turn affects weather patterns. Oceans are a central part of the water cycle and the carbon cycle. And, oceans provide humans with both living and nonliving resources.

What are the ocean’s living and nonliving resources?

Humans depend on the natural resources provided by the ocean. The ocean holds a variety of resources that people often use—from edible fish and algae, which are sometimes called seaweeds, to plants used in medicine, and oil used in vehicles. Resources from the ocean can be living or nonliving.

Living Resources:  Living resources in the ocean include different kinds of animals, plants, and algae. People all over the world use and depend on these living resources every day. Anchovies, pollock, mackerel, herring, and tuna are fish that people harvest from the ocean for food. Shrimp, crab, lobster and other shellfish are different kinds of animals that people eat.

People harvest ocean organisms for many purposes besides food. The gelatin-like texture of algae makes an ideal base for detergents, shampoos, cosmetics, paints, and even ice cream! Sediments containing the hard pieces of certain types of dead algae are used for abrasives and polishes. Many researchers think that other marine organisms may be important sources of chemicals for medicines in the future.

1. Define:  What are some different types of living resources?

Nonliving Resources:  Nonliving resources from the ocean include water, minerals, and fuels. Fresh water can be extracted from ocean water using a process called desalination. Desalination provides fresh water for many dry regions, ships, and submarines.

Minerals are solid substances that are obtained from the ground and from water. When fresh water is removed from ocean water, the salts that are left behind are a valuable mineral resource. More than half of the world’s supply of magnesium, a strong, light metal, is obtained from seawater in this way. The ocean floor is also a source of mineral resources. From the sediments covering the ocean floor, gravel and sand are mined for use in building construction. Manganese and other metals accumulate on the ocean floor. The metals concentrate around pieces of shell, forming black lumps called nodules. The technology for gathering the nodules is still being developed.

Two fuels found in the ocean are oil and natural gas. Deposits of oil and natural gas are located under the sea floor. Drilling through the ocean floor is a way that people obtain these resources. Scientists have also discovered methane hydrates, or methane trapped in ice, on the ocean floor. Since methane is the main component of natural gas, methane hydrates could be an energy source in the future. However, techniques need to be developed to extract the methane from methane hydrates.

2. Define:  What is desalination?

How have humans modified ocean systems?

Humans have modified ocean systems in many ways. Artificial reefs, runoff, and using resources have all modified oceans. Some modifications are positive, but many are not.

Artificial Reefs:  Natural reefs are landforms in shallow ocean water that tiny animals called coral build over thousands of years. Because they offer hard surfaces for plants and animals to attach to, coral reefs attract other ocean life and are productive fishing areas. In areas where coral reefs do not exist naturally, humans have made artificial coral reefs from sunken ships, toppled oil rigs, and even old subway cars. These artificial reefs provide new places for animals to live.

Runoff:  Runoff of chemicals, pesticides and other materials that people use on land has entered the oceans through rivers. Pollution in runoff has a large impact on ocean systems. It can kill the fish, crabs, and other sea creatures that people depend on as sources of food. So pollution in runoff affects the natural balance of ocean ecosystems. Sources of pollution in runoff include household sewage, agricultural waste, and sediments, as shown below.

Use of Resources:  Fish are a major source of food for many people around the world. However, when fish are removed from oceans faster than they can replace themselves, the populations of fish decrease. A decrease in a fish population affects the balance of the local ecosystem.

Drilling for oil can modify ocean systems as well. Pollution from oil rigs affects the living resources near the rig. Oil spills and oil leaks from rigs can harm and damage ocean ecosystems, killing fish, plants, and other wildlife that depend on the ocean.

3. Identify:  What are three ways humans have modified ocean systems?

4. Identify:  Which of the following human activities can have a positive impact on ocean systems?

A drilling for oil B overfishing

C building an artificial reef D allowing fertilizer to enter the ocean

5. Recognize:  List four ways that humans depend on ocean systems.

6. Describe:  Provide two examples of pollution in runoff and describe how this pollution can affect local ocean systems.

7. Infer:  Some areas, such as an island, may not have large sources of fresh water for drinking or agriculture. How can water from the ocean be used as a resource for fresh, usable water?

8. Recognize:  Recognize human dependence on ocean systems by describing how the dramatic decrease in the population numbers of codfish in the Atlantic Ocean affected people in the fishing industry on the coast, people running restaurants, people running supermarkets, and people buying fish to eat.

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