1. Eutrophication is the increase in chemical nutrients, such as the nitrogen and phosphorus often found in fertilizers, in an ecosystem. The added nutrients stimulate excessive plant growth, promoting algal blooms or weeds. The enhanced plant growth reduces oxygen in the land and water, reducing water quality and fish and other animal populations.2. The process by which bodies of water are starved of oxygen and light by algae and other plants that multiply due to excessive concentrations of nutrients such as nitrogen and phosphorous. Typical sources include fertilizer runoff and poorly managed wastewater treatment systems, frequently including home septic systems.