Answer: Photic zone
In an aquatic ecosystem, the region where photosynthesis can occur is called the photic zone.
The photic zone or euphotic zone is the uppermost layer of water in a lake or ocean that is exposed to intense sunlight. On the average, the photic zone of an ocean reaches around 200 meters in depth. At this depth, enough sunlight can penetrate to permit photosynthesis which encourages the growth of a wide variety of flora and fauna.
