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Interactive Textbook 325 The Earth’s Ecosystems

SECTION

2 Marine EcosystemsThe Earth’s Ecosystems

Name Class Date

CHAPTER 20

After you read this section, you should be able to answer these questions:

• What abiotic factors affect marine ecosystems?

• What are the major zones found in the ocean?

• What organisms are found in marine ecosystems?

What Are Marine Ecosystems?Oceans cover almost three-fourths of Earth’s surface!

Scientists call the ecosystems in the ocean marine

ecosystems. Marine ecosystems, like all ecosystems, are affected by abiotic factors.

TEMPERATUREOne abiotic factor in marine ecosystems is the tem-

perature of the water. The water near the surface is much warmer that the rest of the ocean because it is heated by the sun. Deep ocean water is much colder.

Water temperatures at the surface are also affected by latitude. Water near the equator is generally warmer than water closer to the poles. The water at the surface is also warmer in summer than winter.

Temperature affects the animals in marine ecosystems. For example, fish that live near the poles have a chemical in their blood that keeps them from freezing. Most ani-mals that live in coral reefs need warm water to live.

Wat

er d

epth

(m

)

Water temperature (°C)

1,2000 5 10

1,000

800

600

400

200

0

15 20 25 30

Ocean Temperature and Depth

BEFORE YOU READ National Science Education StandardsLS 1a, 3d, 4a, 4b, 4c, 4d

STUDY TIPCompare Create a table comparing the abiotic factors and organisms for each marine ecosystem.

READING CHECK

1. Identify Where is the warmest surface ocean water?

Math Focus2. Read a Graph Abouthow much colder is ocean water at 600 m depth than at 400 m depth?



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Marine Ecosystems continued

WATER DEPTH AND SUNLIGHTTwo other abiotic factors that affect marine ecosystems

are water depth and sunlight. The average depth of the oceans is 4,000 m, but sunlight does not reach deeper than 200 m. Producers that carry out photosynthesis, such as algae, can live only in water less than about 200 m deep.

Plankton are tiny organisms that float near the surface of the ocean. Many kinds of plankton are producers. These phytoplankton use photosynthesis to make their own food. They are the base of most ocean food chains. Large consumers, such as whales, feed on these tiny producers.

Marine ecosystems support many different organisms. Both large humpback whales and tiny phytoplankton live near the surface of the ocean.

What Are the Major Zones in the Ocean?Scientists divide the ocean into zones. The divisions

are based on things such as water depth, the amount of sunlight, and water temperature.

THE INTERTIDAL ZONEThe intertidal zone is where the ocean meets the

shore. The organisms of the intertidal zone are covered with water at high tide and exposed to air at low tide.

The Intertidal Zone Sea grasses, periwinkle snails, and herons are common in an intertidal mudfl at. Sea stars and anemones often live on rocky shores, while clams, crabs, snails, and conchs are common on sandy beaches.

READING CHECK

3. List What are the three main abiotic factors that affect marine ecosystems?

TAKE A LOOK 4. Identify In the picture, which organism is the producer and which is the consumer?

Say ItShare Experiences In a group, discuss the abiotic factors and the living organisms you have seen or might see at the beach.

TAKE A LOOK 5. Explain Why is it diffi cult for many sea creatures to live in the intertidal zone?



SECTION 2

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TAKE A LOOK 6. Identify What are the two main kinds of producers in the neritic zone?

READING CHECK

7. Explain Why do phytoplankton need to live near the surface?

TAKE A LOOK 8. Explain How can the consumers that live in deep waters survive if there are no producers present?

THE NERITIC ZONEThe neritic zone is further from shore. In this zone, the

water becomes deeper as the ocean floor starts to slope downward. This water is warmer than deep ocean water and receives a lot of sunlight. Corals and producers thrive in this zone. Sea turtles, sea urchins, and fishes are some of the consumers of this zone.

The Neritic Zone Although phyto-plankton are the major producers in this zone, seaweeds are common, too. Sea turtles and dolphins live in the neritic zone. Other animals, such as corals, sponges, and colorful fi shes, contribute to this vivid landscape.

THE OCEANIC ZONEIn the oceanic zone, the sea floor drops off quickly. The

oceanic zone extends from the surface to the deep water of the open ocean. Phytoplankton live near the surface, where there is sunlight.

Consumers such as fishes, whales, and sharks live in the oceanic zone. Some of the animals live in deep waters, where there is no sunlight. These animals feed on each other and on material that sinks from the surface waters.

The Oceanic Zone Many unusual animals are adapted for the deep ocean. Whales and squids can be found in this zone. Also, fi shes that glow can be found in very deep, dark water.



SECTION 2

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THE BENTHIC ZONEThe benthic zone is the ocean floor. It does not get any

sunlight and is very cold. Fishes, worms, and crabs have special features to live in this zone. Many of them feed on material that sinks from above.

Some organisms, such as angler fish, eat smaller fish. Other organisms, such as bacteria, are decomposers and help break down dead organisms.

The Benthic Zone Organisms such as bacteria, worms, and sea urchins thrive on the sea fl oor.

What Are Some Marine Ecosystems?Life on Earth depends on the ocean. The water that

evaporates from the ocean becomes most of the rain and snow that falls on land. The ocean affects world climates and wind patterns. People depend on the ocean for food.

Many different kinds of organisms live in the ocean. They live in the many ecosystems in the different zones of the ocean.

THE SARGASSO SEAFloating mats of algae in the middle of the Atlantic

Ocean make up the base of the Sargasso Sea ecosystem. Many animals live in this ecosystem. Most of them are omnivores that can eat many different organisms.

POLAR ICEThe icy waters near the poles are rich in nutrients that

support large numbers of phytoplankton. These produc-ers can support many types of consumers. One of these is a small shrimplike organism called krill. Larger consum-ers, such as fish, eat krill. These consumers, in turn, serve as food for other consumers, such as seals.

TAKE A LOOK 9. Describe What abiotic factors do organisms that live in the benthic zone need to adapt to?

Critical Thinking10. Predict Consequences How would humans be affected if there were no oceans?



SECTION 2

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INTERTIDAL ECOSYSTEMSOrganisms in intertidal ecosystems must be able to live

both underwater and in the air. Those that live in mudflats and beaches may dig into the ground during low tide.

On rocky shores, organisms have adaptations to keep from being swept away by crashing waves. For example, seaweeds use structures called holdfasts to attach them-selves to rocks. Other organisms, such as barnacles, attach themselves to rocks with a special glue. Sea stars feed on these organisms.

ESTUARIESAn estuary is an area where fresh water flows into

the ocean. The water in an estuary is a mix of fresh water from rivers and salt water from the ocean. Organisms that live in estuaries must be able to survive the changing amounts of salt in the water.

The fresh water that flows into an estuary is rich in nutrients washed from the land. The nutrients in the water support large numbers of producers, such as algae. The algae support many consumers, such as fish and shellfish.

CORAL REEFSCoral reefs are named for the small animals called

corals that form the reefs. Many of these tiny animals live together in a colony, or group. When the corals die, their hard skeletons remain. New corals grow on the remains.

Over time, layers of skeletons build up and form a rock-like structure called a reef. The reef is a home for many marine animals. These organisms include fishes, sponges, sea stars, and sea urchins. Because so many kinds of organisms live there, coral reefs are some of the most diverse ecosystems on Earth.

Coral reefs are very diverse marine ecosystems.

READING CHECK

11. Describe How do organisms in intertidal ecosystems protect themselves from being washed away by waves?

READING CHECK

12. Explain How is a coral reef both a living and a nonliving structure?



Name Class Date

Section 2 Review NSES LS 1a, 3d, 4a, 4b, 4c, 4d

SECTION VOCABULARY

estuary an area where fresh water mixes with salt water from the ocean

plankton the mass of mostly microscopic organisms that fl oat or drift freely in freshwater and marine environments

1. Describe What unique abiotic factor do organisms in an estuary have to adapt to? What causes this abiotic factor?

2. Describe What are some of the different kinds of producers found in marine ecosystems?

3. Apply Concepts Complete this food chain that shows the flow of energy through a polar ice ecosystem.

krill seals

4. Explain Why are there few producers below 200 m in the ocean?

5. Identify What abiotic factors make the neritic zone a good home for many different organisms?


Interactive Textbook Answer Key 22 Life Science

Life Science Answer Key continued

5. Nitrogen fixation is the process in which bacteria in soil change nitrogen gas into a form that plants can use.

6. molecules that contain carbon

SECTION 2 ECOLOGICAL SUCCESSION 1. 34%

2. the first species to live or grow in an area

3. Lichens don’t have roots. They get their water from the air, so they do not need soil.

4. tall trees

5. in places where living things already exist

6. weeds

7. conifers

Review 1. Abiotic factors are the nonliving parts of the

environment. They include water, light, and space.

2. Primary succession is the change from bare rock to a community of organisms. Secondary succession is a change in a community where other living things already exist.

3. In secondary succession, there is already soil for new plants to use. In primary succession, soil has to develop before species other than lichens can grow.

4. There is little grass in a mature forest, because the tall trees prevent the light from reaching the ground. Nuts grow on many kinds of trees. Therefore, there would be more nut eaters than grass eaters.

5. Tall trees need deep soil. Pioneer species are the first species to live or grow in an area. There usually would not be soil in an area where no living things had been before.

6. the variety of species that live in an area

7. pieces of rock that have been broken down and remains of dead lichens

Chapter 20 The Earth’s EcosystemsSECTION 1 LAND BIOMES 1. Biomes are made of many related

ecosystems.

2. Africa, South America

3. plenty of rain, moderate temperatures

4. deciduous trees and shrubs

5. in cones

6. The evergreen conifers shade the forest floor, but the deciduous trees of the temper-ate forest allow light to reach the ground.

7. Coniferous forests get less rainfall than some other biomes.

8. Most of the animals are found in the trees.

9. The plants grow above the ground to get sunlight, which is lacking on the forest floor.

10. camouflage, hiding in burrows

11. The savanna gets about twice as much rain.

12. escaping the heat and hiding from predators

13. 25 cm � 2.54 cm/in. � about 10 in.

14. Growing close to the ground helps protect the plants from the cold and wind.

15. They are both large herbivores (consumers).

Review 1. Tundras, like deserts, receive little rainfall.

Tundra is not hot like most deserts, so it is a “frozen desert.”

2. Temperate grassland

Savanna

Abiotic factors warm summers and cold winters

constant warmth with seasonal rains

Types of producers

grass with a few trees

grass with a few trees

Types of consumers

herbivores such as prairie dogs and bison; predators such as coyotes

herbivores such as elephants, giraffes, zebras, and wildebeest; predators such as lions

3. Some plants have special spreading roots to gather rainfall before it evaporates. Many desert plants can store water in their stems or roots.

4. Alpine tundra is found at the tops of tall mountains; polar tundra is found at or near the poles.

SECTION 2 MARINE ECOSYSTEMS 1. near the equator

2. about 10°C

3. depth, sunlight, and temperature

4. The whale is the consumer, and the plankton is the producer.

5. The intertidal zone is regularly exposed to air.

6. phytoplankton and seaweed

7. They need sunlight for photosynthesis.

8. They eat each other and material that sinks from surface waters.

9. cold temperatures, no light, high pressure


Interactive Textbook Answer Key 23 Life Science

Life Science Answer Key continued

10. There would be little precipitation, climates would be different, and there would be less food for humans.

11. They attach themselves to rocks and other hard objects.

12. Most of a coral reef is the nonliving remains of dead corals. It also contains living corals and many other organisms.

Review 1. The water in estuaries contains a changing

amount of salt because fresh water is mixing with water from the ocean.

2. The main producers in most marine ecosys-tems are microscopic, single-celled phytoplank-ton. Other producers are algae, such as kelp.

3. phytoplankton krill fishes seals

4. Most producers use sunlight to carry out photosynthesis. Since sunlight does not pen-etrate below 200 m, these producers cannot live at such depths.

5. The neritic zone has relatively shallow water, a lot of light, and fairly warm tem-peratures. These conditions make the neritic zone habitable by many different organisms.

SECTION 3 FRESHWATER ECOSYSTEMS 1. It gets wider.

2. tadpoles and some insects

3. There is no sunlight.

4. Plants and other producers grow in the lit-toral zone and the open-water zone. These zones get plenty of sunlight.

Scavengers and decomposers live in the deep-water zone and eat dead organisms that fall from the water above.

5. an area with a lot of water in the soil or that is sometimes underwater

6. A swamp has trees growing in it, and a marsh does not.

7. It is abiotic because it is not alive.

Review 1. The littoral zone is shallow, allowing for

rooted plants such as cattails. The open-water zone is too deep for rooted plants, so the main producers are phytoplankton.

2. Swamp producers are mostly trees and vines. Marsh producers are mostly grasses and reeds.

3. fishes, turtles

4. Some abiotic factors are fast-moving water,

abundant sunlight, and changing water levels.

5. From left to right:

The pond slowly fills with sediment. Plants grow in the new soil, closer and closer to the center of the pond.

Eventually, the pond is completely filled with new soil. Forest plants begin to grow.

Chapter 21 Environmental Problems and SolutionsSECTION 1 ENVIRONMENTAL PROBLEMS 1. No, some pollution is caused by natural events.

2. medical wastes, lead paint

3. Type of pollution

Examples or sources

Harmful effects

Chemicals CFCs, PCBs, fertilizer

destroy ozone layer, cause cancer, pollute soil and water

Nuclear wastes nuclear power plants

can cause cancer or radiationpoisoning

Noise airplanes, loud music

affects your ability to think clearly, harms your hearing

Greenhousegases

carbon dioxide cause global temperaturesto rise

4. Old refrigerators still release CFCs.

5. No, greenhouse gases keep Earth warm enough for life to exist. However, too many greenhouse gases can cause global tempera-tures to rise.

6. Renewable resources Nonrenewable resources

sun oil

wind coal

trees natural gas

7. They may compete with native species for resources. They may also kill the native species.

8. Some resources may be depleted. One day there may not be enough resources for everyone.

9. when all the trees in a forest are cut down

10. Nonpoint-source—it has many sources.

Review 1. Overpopulation can lead to depletion of

nonrenewable resources or to overuse of renewable resources, both of which can create pollution and can lead to habitat destruction and a loss of biodiversity.

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CHAPTER SECTION 2 Marine Ecosystems - PC\|MACimages.pcmac.org/SiSFiles/Schools/GA/DouglasCounty/ChapelHill... · • What abiotic factors affect marine ecosystems? • What are the