Question

How would an ecosystem be affected if a new tertiary consumer were brought into the ecosystem? Be specific and include details about how each trophic level would be impacted.  

Answer 1

In ecology, a  food chain is a series of organisms that eat one another so that energy and nutrients flow from one to the next. For example, if you had a hamburger for lunch, you might be part of a food chain that looks like this: grass →→ cow →→ human. But what if you had lettuce on your hamburger? In that case, you're also part of a food chain that looks like this: lettuce →→right arrow human.

Now suppose a food chain in forest ecosystem as below:

Berries and Flowers (autotrophs)>>> Deer (Primary Consumer)>>>Hyenas and Foxes (Secondary Consumers) >>> Puma (as Tertiary Consumers)

Now if a new tertiary consumer such as mountain lion enters this ecosystem then it will have negative effect on ecosystem health and stability of ecosystem. As tertiary consumers (Bear and Mountain Lion in this case) would feed upon same number of secondary consumers e.g Hyenas and foxes in this case. Due to less prey population, it will lead to either decimated population of secondary consumers and resulting destabilised/collapsed ecosystem or it will lead to death of the tertiary consumers due to lack of or insufficiency of prey/ food.

In the first case if population of secondary consumers goes on steep decline then the population of primary consumers will go up. Therefore autotrophs would also grow well and may increase beyond the carrying capacity of the ecosystem. So all trophies levels would be impacted.
  
And in second case/possibility also due to the tertiary consumers decline, there would be spurt in population of secondary consumers. Higher Secondary consumers population (e.g Hyenas and Foxes in this case) would eat up nearly all primary consumers due to which again there would be very high and spurious growth of autotrophs (berries and flowers etc. in this case) which may go beyond carrying capacity of the ecosystem. Hence in this case also all the trophic levels of the ecosystem would be impacted negatively, which ultimately will destabilise the ecosystem.

Also since different food chains are intimately linked in a web like network called as food web, therefore ultimately in any case if new tertiary consumers join ecosystem, then it will affect all trophic levels and ecosystem will be destabilised.