Which action is harmful to organisms living in water ecosystems

General pollution! as well as cultural eutrophication! could be harmful to water ecosystems and are in fact the most prominent reason. pollution could include excess fertilizer run off going into a creek. the nitrogen and phosphorus will create a perfect environment for algae and bacteria. thus leading to cultural eutrophication.

The light is great source of energy

Your gonna need to upload an image with the question : )