Is pollution from pesticide or man harming the animals?

Yes, very much so. I have done research on the Chesapeake bay and know that run off from the many agricultural land in the area goes into the bay. The nutrients in the run off is then used by algae to create massive algae blooms. Theses algae blooms then cover up al the bay grasses and don't allow sunlight to show through. this prevents photosynthesis from happening. The seaweed dies. Then the algae dies. This leaves no more plants to create oxygen for the animals living in the area. The animals die and dead zone is formed. Also, acid rain is very harmful to plants. The pH of acid rain is more acidic than normal rain. After extensive exposure to the rain, plants wither and die. In extreme cases, trees and forests will become barren.