What is eutrophication?

Eutrophication (also called algal bloom) is a massive growth of green plants in lakes and rivers, caused by the use of fertilisers in industry, washed off the land by rain.The fertilisers cause the green plants to grow, and as they do they cover the surface of the lake, preventing sunlight from reaching plants so they can no longer photosynthesise. This means that the plants respire and start using oxygen from the water, causing oxygen depletion. Plants die due to the depletion and lack of photosynthesis, and are broken down by decomposers, which further aid in the oxygen depletion. Eventually the oxygen levels become so low that aquatic life such as fish and decomposers can no longer be supported by the lake and they too die.