oxycline

An oxycline is a zone in a body of water where the dissolved oxygen concentration changes rapidly with depth. Typically, this rapid change occurs in a relatively narrow layer. Below the oxycline, dissolved oxygen levels are significantly lower than those above it. This phenomenon is common in stratified bodies of water, such as lakes and the ocean, where different water layers have distinct temperatures and densities, preventing them from mixing easily.

The formation of an oxycline is influenced by several factors, including the rate of oxygen consumption by organisms in deeper waters, the limited supply of oxygen from the surface due to reduced mixing, and the presence of a thermocline or halocline, which acts as a barrier to vertical water movement. In freshwater lakes, an oxycline often forms during the summer stratification period. In the ocean, it can be found in areas with limited ventilation, such as semi-enclosed seas or oxygen minimum zones.

The presence and depth of an oxycline have significant implications for aquatic life. Organisms that require high oxygen levels are restricted to the waters above the oxycline. Below it, only species adapted to low-oxygen conditions can survive. Changes in an oxycline's position or intensity, often linked to climate change or nutrient pollution, can thus have profound effects on marine and freshwater ecosystems.