Describe the effects of nitrogen and phosohorus fertiliser leaching into a lake

This will cause eutrophication. Under normal circumstances, nutrients are a limiting factor for algal growth. When the fertiliser leaches into the lake, the excess nutrients will therefore allow algae at the surface to grow and multiply rapidly in an algal bloom.The mass of alge block light from reaching the lake bed, preventing photosynthesis in the plants that grow there. Without the ability to photosynthesise, the plants die.The dead organic plant material is then decomposed by bacteria. The respiration of these bacteria uses up large quantities of oxygen, leaving too little to support large-bodied aquatic animals such as fish, which die off.