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Get It?
Infer
how climate change will likely change the graph in
Figure 18
.
The Water on Earth
When you think about water on Earth, you might recall a vacation at the ocean or
a geography lesson in which you located Earth’s oceans and seas. You probably have
heard about other large bodies of water, such as the Amazon River and the Great Salt
Lake. A photograph of Earth from space shows Earth as mainly blue in color because
the planet is largely covered with water. Ecologists recognize the importance of water
because of the biological communities that water supports. In this lesson, you will read
about freshwater, transitional, and marine aquatic ecosystems. You also will read about
the abiotic factors that affect these ecosystems.
Freshwater Ecosystems
The major freshwater ecosystems include ponds, lakes, streams, rivers, and wetlands.
Plants and animals in these ecosystems are adapted to the low salt content in freshwater
and are unable to survive in areas of high salt concentration. Only about 2.5 percent
of the water on Earth is freshwater, as illustrated by the circle graph on the left in
Figure 18
on the next page.
The graph on the right in
Figure 18
shows that, of the 2.5 percent of Earth’s water that
is fresh, 68.9 percent is contained in glaciers, 30.8 percent is groundwater, and only 0.3
percent is found in lakes, ponds, rivers, streams, and wetlands. Interestingly, almost all
of the freshwater species live in this 0.3 percent.
LESSON 3
AQUATIC ECOSYSTEMS
FOCUS QUESTION
What are some examples and characteristics of aquatic
communities?
Disciplinary Core Ideas
Crosscutting Concepts
Science & Engineering Practices
3D THINKING
C
C
C
S
E
P
D
C
I
COLLECT EVIDENCE
Use your Science Journal to
record the evidence you collect as
you complete the readings and
activities in this lesson.
INVESTIGATE
GO ONLINE
to find these activities and more resources.
BioLab:
A pond in a jar
Plan and carry out an investigation
to determine
the stability and change
of a miniature
ecosystem.
Virtual Investigation:
Communities and Ecosystems
Use a model
to create a
stable
and balanced marine
ecosystem.
Lesson 3 • Aquatic Ecosystems
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