What is the main consequence of stratification in lakes?

Stratification in lakes refers to the layering of water based on temperature and density, which typically occurs during warmer months when the surface water warms up and becomes less dense than the cooler, denser water below. This process leads to distinct thermal layers, or strata, in the lake: the epilimnion (warm surface layer), metalimnion (thermocline), and hypolimnion (cold bottom layer).

The main consequence of this stratification is the seasonal variation in temperature and oxygen levels throughout these layers. In the upper layer, the warmer water can support higher levels of dissolved oxygen due to photosynthesis by aquatic plants and phytoplankton. However, below the thermocline, the hypolimnion may become stagnant during stratification, leading to reduced oxygen levels, especially in the absence of mixing. This phenomenon can significantly impact aquatic life, as organisms in the hypolimnion may face hypoxic conditions, especially as the season progresses and organic matter decomposes, consuming available oxygen.

Understanding stratification is essential for managing freshwater ecosystems and ensuring the health of aquatic species, which depend on varying temperature and oxygen levels throughout the year.