Write short notes on Algal bloom
Phosphorus and nitrates dissolved in water act as nutrients and accelerate the growth of algae that may form a mat on the water surface. It is termed algal bloom. Effects: The algae use oxygen at night and may deoxygenate the water enough to kill the fish and other animals. The algal mat at the water surface may block light to the submerged plants. The algae may die and sink, and feed the oxygen-consuming bacteria. They may be pushed onto the shore by wind and decompose, releasing foul gases, such as hydrogen sulfide. Silt and decaying matter may accumulate and finally fill the lake or pond. This process is called senescence. It is a natural stage in the change of a lake into dry land and it becomes barren.
