Top-down Cascades

A top-down trophic cascade occurs due to a change in the balance of the top level predators.

If predators are added to an ecosystem they will find and eat more mid-level consumers, reducing the number of consumers, meaning the number of primary producers and perhaps primary consumers will increase.

However, if predators are removed from the ecosystem the number of mid-level consumers will go up as the predation pressure goes down, effectively increasing the grazing pressure on the primary producers of the ecosystem.

When the top predator, the Shake, disappear their main food-sources will increase in numbers, meaning more Stunions.

When there is an increase in Stunions they will eat more of their prey, the Stackarel and Lumpys.

With increased predation of Stackarel and Lumpbys by the Stunions, the Goslin will find it harder to find food in the lake, so it will search for food elsewhere.

When there are fewer Lumpbys swimming upriver the amount of Phytoyeaston will increase dramatically, and draw in more Balateens.