Which type of water is characterized by high nutrients, more algae, and lower dissolved oxygen?

• A. Oligotrophic water
• B. Eutrophic water
• C. Mesotrophic water
• D. Hypereutrophic water

Answer: (B)

High nutrient levels fuel algal blooms, which is the hallmark of eutrophic water. When nutrients like phosphorus and nitrogen are abundant, algae grow rapidly, increasing productivity. But as these blooms die and decompose, bacteria consume lots of dissolved oxygen, often lowering the dissolved oxygen in the water. This combination—high nutrients, more algae, and lower dissolved oxygen—defines eutrophic water. By contrast, oligotrophic water has low nutrients and is usually clear with higher dissolved oxygen; mesotrophic is intermediate; hypereutrophic is extremely nutrient-rich with even heavier algal blooms and very low oxygen.