Photic zone refers to the upper layer of a water body described by the depth to which sufficient sunlight can penetrate to allow the process of photosynthesis. The abiotic factors, which influences the photic zone are obtainability of light and depth of the photic zone, stratification, temperature, nutrients, salinity, and currents and tides.
The aphotic zone refers to the part of an ocean or lake where there is no or little sunlight. It is usually illustrated as the depths beyond which less than one percent of sunlight goes through. Bio-luminescence is only light found in this zone.
The majority of the food in this zone comes from dead organisms falling to the bottom of the ocean or lake from the overlying waters. The depth of the aphotic zone is highly affected by the factors, like a season of the year and turbidity.
