Answer:
It is the zone in which photosynthesis occurs.
Step-by-step explanation:
The Epipelagic is the uppermost of the oceanic zones and is crucial to the ocean food chain because it is here that photosynthesis can occur thanks to the presence of sunlight.
Phytoplankton live and grow in this zone and are an essential food source for countless marine animals, including whales. Many forms of marine life not only in the Epipelagic but below in the Mesopelagic zone, depend on phytoplankton.
The darker zones underneath the Epipelagic are characterized by having much lower biodiversity since the lack of sunlight and combination of high pressures and cold temperatures makes them more inhospitable.