One change, many effects
Everything is connected.
A polluted pond
Pollution starts killing the plants of a pond.
What could happen next?
What this lesson covers
The idea
Because organisms and their surroundings are interconnected, one small change in an ecosystem, such as loss of one population, can cause cascading effects on many other populations and components.
A polluted pond
Pollution starts killing the plants of a pond.
What could happen next?
- Less oxygen and fewer fish
- Nothing else changes
- The fish multiply
Follow the effects
Press Next step. Each step adds an effect.
Cascading effects
Organisms and their surroundings are interconnected. One small change, such as the loss of one population, can cause many other changes. In the 1980s large-scale harvesting of the Indian bullfrog reduced frog numbers. Frogs eat insects, so agricultural pests rose and farmers used more pesticides.
Because everything in an ecosystem is interconnected, one small change (like the loss of one population) can have cascading effects on many other populations and components.
Notes
In an ecosystem one change leads to another: effects cascade.
Check yourself
One small change in an ecosystem can …
Plants in a pond die from pollution. Oxygen in the water …
Harvesting many frogs led to more agricultural pests because frogs …
More pests made farmers use more …
- affect nothing else. Everything is interconnected.
- only affect one organism. It can affect many populations and components.
- cause cascading effects on many others — correct. Yes!
- decreases — correct. Yes!
- increases. Fewer plants produce less oxygen.
- is unaffected. Fewer plants produce less oxygen.
- make pesticides. Frogs eat insects. With fewer frogs, pests rose.
- eat insects — correct. Yes!
- grow crops. Frogs eat insects.
- sunlight. Farmers used more synthetic pesticides.
- water bodies. Farmers used more synthetic pesticides.
- pesticides — correct. Yes!