Question

Lakes that show overturns twice a year are called:

• A. Monomictic lakes
• B. Dimictic lakes
• C. Eutrophic lakes
• D. Profundal lakes

Hint:

Understanding thermal stratification and turnover in lakes is essential for managing freshwater resources and predicting the impacts of climate change on aquatic ecosystems.

Answer 1

The Correct Option is B

Dimictic lakes experience two turnover periods annually, typically in the spring and autumn when the water temperature at the surface reaches that of the deeper layers, leading to a density-driven mixing of lake waters. This natural phenomenon is driven by the thermal properties of water, which affect its density. In the spring, as ice melts and surface water warms to the same temperature as deeper water, the lake mixes, redistributing nutrients and oxygen throughout the lake. Similarly, in autumn, as surface water cools to match the deeper water temperature, another mixing event occurs. These turnover events are vital for the ecological health of the lake, as they rejuvenate the nutrient supplies and ensure oxygen distribution throughout the water column, supporting aquatic life across all depths.