With the use of high–yielding varieties of crops, the use of fertilizers and pesticides has increased a lot. Excess fertilizers may mix with surface water and may get drained into water bodies (surface runoff). These fertilizers overstimulate the growth of algae, causing eutrophication, and robbing the water of dissolved oxygen vital to other aquatic life. During the past century, lakes in many parts of the earth have been severely eutrophied by sewage and agricultural and industrial wastes. Continue reading What is Eutrophication? What are its Causes & Effects?