Water is the most important substance on earth. It is the basis of all life on this planet. Human's behavior such as using pesticides and fertilizers pollutes our water tables. Pollution interferes with ecosystems by killing off animals that drank or animals that ate animals that drank highly polluted water.
Pollution is not a good thing to have large amounts of at all. It poisons animals that drank the polluted water, not only just animals that drank the polluted water, but also animals that eat animals that are contaminated from drinking the polluted water. Humans can upset or even destroy an entire ecosystem by polluting the water that the animals drink and live in with pesticides and fertilizers.
Animals that drink the water have the pollutants in their system, so if another animal should eat that contaminated animal, it too will get contaminated and may very well die as well as the animal that drank the polluted water.
A once stable ecosystem can be disturbed, or maybe decimated do to polluted water.
Actions of humans definitely affect the lives of other animals. We need to stop or at least minimize pollution in waterways, lakes, and rivers. If we don't, there may be a very grim future for wild animals.