Eutrophication. Nitrogen is one of the essential parts of aquatic ecosystems but an increase in the amount of nitrogen leads to an abundant growth of algae and other aquatic plants. On increased production, algae cover the surface of the lakes and river and prevents sunlight on entering the water.
Because of this, photosynthesis in rivers and lakes decreases and this leads to reduced production of oxygen which is essential for aquatic life.
This disrupts the cycle and after some time and the percentage of oxygen decreases which harms marine life and due to this the carbon dioxide production also decreases which ends up killing the plants too. This process is called eutrophication of the water environment.
