Sea Secrets
Sea Connections
Ocean Market
Pollution Solution
Stranded Along the Coast
Reflections on the Sea

OBJECTIVES

• Identify producers and consumers from four marine ecosystems.
• Describe the delicate balance among organisms in each environment.
• Construct a food chain or web from a marine ecosystem.
• List some of the human activities that can upset the balance in marine environments.

MATERIALS

• Student Page
• Globe or world map
• Playing cards to be copied and cut out
• Heavy stock paper for photocopying or pasting cards
• Scissors

SUBJECTS

biology, geography, oceanography, political science, art

1. Motivate students by rapidly spinning a globe and asking them to approximate how much of Earth is covered by ocean. Ask them to think about the variety of marine organisms and habitats that must exist on our watery planet, which is over three-quarters ocean. Then have students locate each of the following on a globe or world map: the Great Barrier Reef in Australia (coral reef); the Weddell Sea, Antarctica (polar ocean); Monterey Bay, California (kelp forest); and the Mid-Atlantic Ridge (hydrothermal vent). (If the Mid-Atlantic Ridge is not shown on your globe or world map, approximate its location by connecting Iceland and the Azores with a large letter C, or look at the map on page 11, the Sea Secrets Student Page.)

2. Using the introduction as a guide, describe to your students some of the amazing biodiversity of ocean life, including marine organisms in hydrothermal vents, coral reefs, kelp forests, and polar oceans. Challenge students to match each of the four ecosystems you have described with the correct location on the globe. Ask them to name the producers and consumers from each ecosystem. Producers always begin the food chain and, in the ocean, are generally algae, although chemosynthetic bacteria are the producers near hydrothermal vents. All the other organisms are consumers.

3. In advance, photocopy the three pages of playing cards and paste copies onto heavy stock paper. Cut each sheet into nine cards along the guide lines. Each complete deck will have twenty-seven playing cards and is suitable for a group of up to four players. After cards are cut out they may be laminated or stored in plastic sleeves designed to hold trading cards.

4. Divide students into groups of four or fewer. Pass out a deck of cards to each group and the Rules of the Game Page to each player. Read through the directions together. Make sure that students understand that they will be trying to collect all five cards from one ecosystem in order to see how they connect to each other. Tell students that only five organisms have been chosen from each ecosystem for the game, but that these representative organisms are part of much bigger food webs from each ecosystem. Read through the Disconnect and Reconnect cards to make sure students understand how they are used in the game.

5. As students start playing, circulate among the groups. As a player is carrying out the directions on a Disconnect card, have that student explain to you the relationship of the organisms within that ecosystem and tell in his or her own words the impact of the card.

6. As a student from one group wins, you might interrupt play to let that student describe the winning hand to the class. Use this as a jumping-off point to talk about how food chains and food webs connect the producers and consumers in an ecosystem. As the students resume playing, tell them that the winner from each group should lay out the winning cards to form a food web for other players to see. Then they can divide and trade the remaining cards so that each player has all five cards of one ecosystem-a winning hand.

7. Ask students to fill in their charts using their cards. Spot check the diagrams of each marine ecosystem. Student food chains and food webs should show a pattern of producers first, then primary consumers (those that eat producers directly), followed by predators. If students use arrows to connect the organisms, the arrow's point should mean "eaten by."

8. When students have finished their pages, discuss which of the Disconnect cards prevented them from winning. This can lead to a discussion of the international problem of overfishing. Explain to students that when too many people haul their fishing nets and cast their lines in the same waters, too few fish are left to reproduce. In addition, some fishing grounds have become polluted, so the overall result is a dramatic drop in the fish population. The overfishing problem is so great in some areas that the government has to limit or halt fishing until certain populations recover. Among those on the "hardest hit list" are the Pacific king crab and the Atlantic cod and haddock. In 1991 the American Fisheries Society announced that about half the nation's stock of salmon was at risk. Even the mighty bluefin tuna, which can weigh fifteen hundred pounds and swim as fast as a speeding car, is down to only 10 percent of its 1980s population. Commercial fishing practices of the past have also harmed nontarget species. In some places enormous driftnets up to sixty kilometers long were set over huge areas of ocean. The fine filaments would catch thousands of fish by the gills, but many other animals would get caught, too. Turtles, birds, sharks-even whales and dolphins-drowned in these nets. Loud cries from conservationists and governments brought about a ban on these driftnets, although shorter nets are still used close to shore. Other fishing gear still in use catches and kills young fish and other unwanted animals by mistake.

9. Ask students to imagine that they make their living catching fish, as some of their parents and grandparents did. Ask them to think about how they would feel if the government set a limit on their catch. Their first reaction might be to the loss of income; however, over the long term they should be concerned with finding ways to prevent the disappearance of the species.

10. Ask students if they've ever played the card game Go Fish. Then ask them why the game they have just played could be called Don't Go Fish. They might answer that overfishing causes the reduction or loss of desirable and profitable species of fish and shellfish. It also disturbs the delicate balance of producers and consumers in each marine ecosystem. The purpose of the card game is to show how both natural events and human activities, such as overfishing, can disturb this balance and break the links that connect species in an ecosystem.

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