Name: ______________________

Period______

Snake River

Food Web Activity

Background:

Read through the text below. Using the information below, design a food web and answer the analysis questions.

The Snake River offers some of the most beautiful scenic landscapes found in East Central Minnesota. The upper Snake River’s banks are heavily forested with birch, aspen, oak, maple, ash, elm, and some black spruce trees. From Mora to Pine City, the river travels through wooded banks as well as farmland. Below Cross Lake, the sandstone bluffs and forested banks offer spectacular scenic views.

The river provides habitat for a wide range of fish, which include catfish, walleye, northern pike, and smallmouth bass. Lake sturgeon are also found here, making the Snake River one of the few rivers in Minnesota that contain this rare species. White-tailed deer, black bears, red fox, beavers, and muskrats and an occasional otter can also be seen. Bobcats, coyotes, minks, and raccoons are also found in the area. Ruffed grouse, numerous waterfowl and many different songbirds may be sighted as well. The river also provides ideal habitat for a wide variety of algae, plants, crustaceans and many species of insects.

Algae and some species of bacteria can be observed growing in the water. Common reeds are also prevalent in the backwaters. On the water’s edge aquatic plants such as cattails grow. Water boatmen are observed swimming in the water. They are eating the algae, common reeds, and cattails. Mosquito larvae also eat the algae while the snail eats both the algae and cattails. A painted turtle pokes its nostrils above the water. The turtle eats the algae too, as well as feeding on snails, water boatman, and crayfish. The water boatman provides food for many species including smallmouth bass, frogs, diving beetles and dragonfly larvae. The crayfish are scavengers, feeding on rotting common reeds, cattails, algae and even fish carcasses. Bacteria and fungi also help break down dead material, such as dead snails and frogs, and rotting common reeds and cattails by digesting it and recycling nutrients in the ecosystem. The mosquito and dragonfly larvae are considered a delicacy for several varieties of fish, such as the smallmouth bass.

Birds are in abundance along the river. Wood ducks are feeding on fish, dragonfly larvae and diving beetles, while the occasional great blue heron feeds on fish, frogs, and dragonfly larvae. The beautiful bald eagle is often seen along the river. Bald eagles feed on a variety of fish and an occasional duck or turtle.

Procedure:

1. Using the description of the Snake River on the front page, make a rough draft on notebook paper of the food web for this ecosystem.
2. Using the text on the previous page and your food web rough draft, fill in the chart below by identifying each organisms as either a producer, 1st order consumer, 2nd order consumer (or higher), or decomposer and placing them in the correct box.
3. Using the cards on the back page, draw, label, and color each of the organisms and carefully cut them out.
4. Construct your food web by placing the producers near the bottom of your poster and build up – with the higher order consumers toward the top of the poster. Do not glue the organisms on yet!
5. Continue to rearrange the organisms until you find the “best fit.” When you are happy with your placement, glue the organisms in place.
6. Draw the arrows to show the flow of energy. Remember, the arrows flow from what is being eaten to what is doing the eating.
7. Give your food web poster a title and answer the analysis questions.

Analysis:

1. Which of the organisms in your food web contain chlorophyll? Are these organisms producers or consumers? Explain.

2. List the organisms in your food web that feed on algae.

3. Find a food chain within your food web that contains at least four organisms. Place these organisms in the pyramid below. Place the producer at the bottom and the highest order consumer at the peak. 

4. The species in the lowest levels of the pyramid contain the largest number of individuals while species at the peak contain the lowest population. Explain why this occurs. (Hint: flow of energy)

5. Which organisms are decomposers in your food web? What is their function?

6. Predict what would happen to the Snake River ecosystem if people dumped their used engine oil in the river. Explain.

7. Predict what would happen to the Snake River ecosystem if the water boatmen went extinct. Explain.