The Cascade Effect
The Cascade Effect is a Grade 7 science concept from Amplify Science (California) Chapter 3: Indirect Effects in Ecosystems, illustrating a trophic cascade triggered by the collapse of Walleye Pollock populations. With fewer Pollock eating zooplankton, zooplankton increased, providing more food for Moon Jellies whose population then exploded — demonstrating how one species decline can indirectly cause distant population booms.
Key Concepts
Evidence shows the Walleye Pollock population collapsed. This is a trophic cascade .
With fewer Pollock eating zooplankton, the zooplankton population increased. This surplus of food allowed the Moon Jellies to reproduce more. Thus, the decline of a competitor indirectly caused the jelly explosion.
Common Questions
What is a trophic cascade?
A trophic cascade is a chain of indirect effects that ripples through a food web when one population changes dramatically. A change at one trophic level triggers unexpected changes in other levels through their shared food web connections.
How did the Walleye Pollock collapse cause a Moon Jelly explosion?
When Walleye Pollock populations collapsed, they ate less zooplankton, causing zooplankton to increase. This surplus food allowed Moon Jellies — which also eat zooplankton — to reproduce rapidly, causing a population explosion.
Why are indirect effects important in understanding ecosystem changes?
Indirect effects mean the true cause of a population change may not be a direct predator or competitor. Understanding cascade effects helps scientists predict ecosystem responses to disturbances.
What do Grade 7 students learn about cascade effects in Amplify Science?
In Chapter 3 of Amplify Science California Grade 7, students trace how the Pollock population collapse indirectly triggered a Moon Jelly explosion through zooplankton, illustrating trophic cascades.