What is meant by eutrophication?
Eutrophication is caused by an excessive amount of nitrogen and organic compound from fertilisers that are not absorbed by plants washed into nearby rivers and lakes. These organic compounds promote the growth of algae, and the algae may overgrow and cover the entire water surface, which prevents light from penetrating into the water. The submerged plants cannot photosynthesis with the light energy and they die. The dead bodies are then decomposed by bacteria, which uses up more oxygen for decomposition. The fishes and other aquatic organisms are then deprived of oxygen and they die.
