What is the importance of turnover in temperate lakes?

• A. It helps to set up a thermocline in the lake.
• B. It brings benthic organisms to the surface, where they have access to more light and oxygen.
• C. It occurs constantly during the summer, giving the lakes a murky appearance.
• D. It changes the relative positions of the photic and aphotic zones.
• E. It brings oxygen-rich water to the bottom and nutrient-rich water to the surface.

Answer: (E)

Verified step by step guidance

1. Understand the concept of lake turnover: Lake turnover is a process that occurs in temperate lakes, typically during the fall and spring, where the water layers mix due to changes in temperature and density.
2. Recognize the role of temperature: In temperate lakes, the surface water cools down in the fall, becoming denser and sinking, which causes the water from the bottom to rise. This process is reversed in the spring as the surface water warms up.
3. Identify the benefits of turnover: The mixing of water layers during turnover is crucial because it brings oxygen-rich water from the surface to the bottom and nutrient-rich water from the bottom to the surface.
4. Consider the ecological impact: This exchange of oxygen and nutrients supports aquatic life by ensuring that organisms at different depths have access to the resources they need for survival.
5. Evaluate the options: Among the given options, the correct answer is that turnover brings oxygen-rich water to the bottom and nutrient-rich water to the surface, which is essential for maintaining a healthy aquatic ecosystem.