8.5 Eutrophication

Explain the environmental effects of excessive use of fertilizers and detergents on aquatic ecosystems.

• Eutrophication occurs when a body of water is enriched in nutrients.
• The increase in nutrients in eutrophic aquatic environments causes an algal bloom. When the algal bloom dies, microbes digest the algae, along with the oxygen in the water, leading to a decrease in the dissolved oxygen levels in the water. The lack of dissolved oxygen can result in large die-offs of fish and other aquatic organisms.
• Hypoxic waterways are those bodies of water that are low in dissolved oxygen.
• Compared to eutrophic waterways, oligotrophic waterways have very low amounts of nutrients, stable algae populations, and high dissolved oxygen.
• Anthropogenic causes of eutrophication are agricultural runoff and wastewater release.
• Enduring understanding STB-3: Human activities, including the use of resources, have physical, chemical, and biological consequences for ecosystems.