Alligators in the environment?

what purpose do alligator serve in the environment? do they still serve a purpose i know the earth has changed since dinosaurs time, since it has change so drastically do alligators still play the role they use to play in primitive times. it kind makes me think of sharks there very beneficial to the environment they have been around since dinosaur times there still serving there purpose on the food chain also still keep the reefs alive that make up most of our oxygen. i guess we won t know what alligator do till they become extinct but i doubt that would happen.