In a system with four trophic levels (producers, herbivores, and two levels of predators) exhibiting trophic cascades, what would you expect to happen if a species at the fifth trophic level is added (a predator on the current top predator

The population of fourth trophic level is decreases.

Explanation:

If a species at the fifth trophic level is added in the ecosystem then there is decrease occur in the population of fourth trophic level because the animals of fourth trophic level is controlled by fifth trophic level through feeding on them. This fifth trophic level is the last trophic level in the system on which no other organisms feeds except decomposers such as fungi and bacteria. These decomposers releases nutrients from the dead bodies which can be used by the producers.

i am sorry but i need more information and a picture.