The ocean zone that contains the greatest biodiversity is the pelagic zone, specifically the epipelagic zone. This zone is also known as the sunlight zone and extends from the surface to about 200 meters deep.
The epipelagic zone is rich in biodiversity because it receives ample sunlight, which supports photosynthesis. This process allows phytoplankton to thrive, forming the base of the marine food web. The abundance of sunlight also supports a wide variety of marine life, including fish, mammals, and invertebrates.
Additionally, the epipelagic zone has a stable temperature and nutrient-rich waters, which further contribute to its high biodiversity. Coral reefs, which are among the most diverse ecosystems on the planet, are also found in this zone.
In summary, the epipelagic zone of the pelagic region is the most biodiverse ocean zone due to its access to sunlight, stable conditions, and nutrient availability.