Food Web Balance

Science, Grade 6


Table Of Contents: Food Web Balance

1. Changes in Population Size
If the population size of a species changes within an ecosystem, the balance of the food web can be disrupted. Over time, all levels of the food web can be affected.
2. Alaskan Marine Ecosystem Example
This food web shows the feeding relationships of organisms in an Alaskan marine ecosystem. If the population of seals and sea lions dramatically decreased, what impact would it have on this food web?
3. Killer Whales Feed on the Otters
Without as many seals and sea lions to eat, killer whales might start feeding on more sea otters, causing a decline in their population.
4. Sea Urchin Overpopulation
With fewer otters as predators, the number of sea urchins would grow and eat more of the kelp forests.
5. Loss of Kelp Habitat
The kelp forests are the habitat for many fish larvae. Loss of this habitat would cause a decline in the fish population.
6. Marine Ecosystem Is Altered
This example demonstrates that the original change in the population of the seals and sea lions could cause a chain reaction of events that would alter the balance of the food web.