Answer/Explanation:
Essential nutrients such as nitrogen, phosphorus, at specific moderate level are needed for the overall functionality of the aquatic ecosystem. However, when excess of these elements infiltrates the aquatic ecosystem, the nutrient overload causes a surge in the growth of aquatic plant. For example, algal bloom. These increased growth of aquatic plant further takes up space and oxygen, prevents sunlight and later leads to what is known as "dead zone". It is a condition of an ecosystem having little or no biological activity. Aquatic life is impacted negatively when this occurs.
These are the changes that occurs as a result of nutrient loading.