Is the citric acid cycle the same thing as fermentation​

No because the net yields of ATP, NADH and FADH2 during glycolysis, pyruvate oxidation and the citric acid cycle. ... In the absence of oxygen, pyruvate undergoes fermentation (either ethanol or lactate, depending on the organism). Fermentation does not generate any additional energy, however, NAD+ is regenerated.

If you remove all the lions from the savanna it will lead to a increase of gazelle and a increase of cheetahs becasue of no competition