The excessive use of nitrogen-based fertilizers causes runoff that increases the nitrogen content of lakes and bays. The nitrogen directly affects the aquatic ecosystem by_

C or the third answer choice

Explanation:

If algae excessively grows on the tops of the water, it can block sunlight. That will make the underwater plants die, and the animals that eat those underwater plants will slowly have less to eat if they can't adapt quickly enough. When the algae dies, it takes oxygen with it. If it take all of the oxygen in the water, that whole ecosystem could potentially die as well.

answer; /// i believe that the correct answer is (50%);

where is the scientific experiment?