Explain one reason why the population of marsh grasses might increase if the population of herons decrease

Herons are very large birds, and due to their intimidating size, they have very little predators. They have a varied diet and consume many different prey (fish, snakes, amphibians, and probably many other small animals). If the population of herons would decrease, the population of the other organisms living in the same environment would increase since they would have a greater chance at survival (since they are not being eaten by the herons)