The layer that lacks oxygen is the oxygen minimum layer (OML), which is found in the mesopelagic zone (twilight zone) of the ocean. This layer occurs between depths of 100 and 2000 meters, where oxygen levels are at their lowest.
The OML is characterized by:
- Stable conditions of continuously low oxygen level: This is due to the breakdown of organic matter by bacteria, which consumes oxygen.
- Low temperatures: The temperatures in the OML are relatively stable and low due to the lack of sunlight.
The presence of the OML has significant impacts on marine life. Some organisms have adapted to survive in low-oxygen environments, while others have to migrate to shallower waters.
Examples of adaptations include:
- Increased gill surface area: This allows organisms to extract more oxygen from the water.
- Reduced metabolic rate: This allows organisms to survive on less oxygen.
- Anaerobic respiration: Some organisms can respire without oxygen, using other chemicals as energy sources.
The OML is a critical component of the ocean ecosystem and plays a vital role in the global carbon cycle.
