Understanding the Freshwater Ecosystem
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More than one tenth of the U.S. population and one quarter of the Canadian population live in the Great Lakes region. People in both countries use the lakes in many ways. They depend on them for drinking water. They use water from the lakes in factories. They use the lakes for shipping, fishing, and recreation. And they build cities on their shores.
One of North America’s Largest Watersheds Think of standing on a hill and pouring water from a large container onto the ground. The water would flow downhill. While running downhill, some of the water would soak into the ground. If there were a hole along the way, water would fill it to form a tiny lake. You would have created your own tiny watershed.
A watershed is a geographic area that includes all of the land and waterways that drain into a body of water. Draw a picture of a watershed next to the definition you wrote. Watersheds come in many shapes and sizes. They can include hills and valleys and cities and towns. Smaller watersheds can drain into larger watersheds. The Great Lakes region is one of the largest watersheds in North America.
The Great Lakes are so big that they look and act like oceans. In fact, people have called them “the fourth seacoast” of the United States. But unlike the oceans, the lakes are filled with fresh water that has little or no salt. That is why they are also called “the sweetwater seas.”
One of North America’s Largest Watersheds Think of standing on a hill and pouring water from a large container onto the ground. The water would flow downhill. While running downhill, some of the water would soak into the ground. If there were a hole along the way, water would fill it to form a tiny lake. You would have created your own tiny watershed.
A watershed is a geographic area that includes all of the land and waterways that drain into a body of water. Draw a picture of a watershed next to the definition you wrote. Watersheds come in many shapes and sizes. They can include hills and valleys and cities and towns. Smaller watersheds can drain into larger watersheds. The Great Lakes region is one of the largest watersheds in North America.
The Great Lakes are so big that they look and act like oceans. In fact, people have called them “the fourth seacoast” of the United States. But unlike the oceans, the lakes are filled with fresh water that has little or no salt. That is why they are also called “the sweetwater seas.”
A Vast and Varied Ecosystem The Great Lakes region is a vast ecosystem. One way to understand how the living things in the Great Lakes ecosystem are related to each other is to look at who eats what. These relationships make up what scientists call a food web. Food webs include both plants and animals that feed on each other.
Every ecosystem has its own food web. A food web is made up of many food chains. A food chain is a series of plants and animals, each of which depends on the next for food. In the Great Lakes ecosystem, for example, one food chain might begin with plants that grow in lakes and rivers. The next link in the chain might be insects that feed on those plants. These insects are eaten by tiny fish. The tiny fish are then eaten by larger fish. The larger fish, in turn, may be eaten by an eagle sitting at the top of the food chain. Another food chain might begin with tiny organisms known as algae and end with a river otter.
The food web is an important part of any ecosystem. If one part of the food web is harmed, it affects all of the living things in the ecosystem. For example, if a fish is poisoned by pollution, any animal that eats that fish will be poisoned as well. Or, if a type of plant or fish is lost from an ecosystem, all animals that feed on that plant or fish will lose part of their food supply. In this way, all living things in a food web depend on each other for their survival. Use this paragraph to answer the question, "What might happen to the ecosystem if a certain type of plant growing along the banks of the lake are destroyed?"
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Every ecosystem has its own food web. A food web is made up of many food chains. A food chain is a series of plants and animals, each of which depends on the next for food. In the Great Lakes ecosystem, for example, one food chain might begin with plants that grow in lakes and rivers. The next link in the chain might be insects that feed on those plants. These insects are eaten by tiny fish. The tiny fish are then eaten by larger fish. The larger fish, in turn, may be eaten by an eagle sitting at the top of the food chain. Another food chain might begin with tiny organisms known as algae and end with a river otter.
The food web is an important part of any ecosystem. If one part of the food web is harmed, it affects all of the living things in the ecosystem. For example, if a fish is poisoned by pollution, any animal that eats that fish will be poisoned as well. Or, if a type of plant or fish is lost from an ecosystem, all animals that feed on that plant or fish will lose part of their food supply. In this way, all living things in a food web depend on each other for their survival. Use this paragraph to answer the question, "What might happen to the ecosystem if a certain type of plant growing along the banks of the lake are destroyed?"
Click here to continue!