How does the aphotic zone differ from the photic zone in energy use?

In an inland water ecosystem, the photic and aphotic zones are distinguished by their light availability and the resulting balance of energy production and consumption:

• Photic Zone (Trophogenic Zone): This is the upper layer of the water where sunlight penetrates, allowing for photosynthesis by plants and algae. In this zone, the production of biochemical energy through photosynthesis exceeds the energy consumed through respiration and decomposition.1
• Aphotic Zone (Tropholytic Zone): This region lies beneath the photic zone and is characterized by perpetual darkness. Because there is insufficient light for photosynthesis, the production of energy is absent or negligible. Consequently, the consumption of energy by animals and decomposers exceeds its production.1

These two zones are separated by a plane of compensation, where the rates of primary production and consumption are equivalent. While this plane shifts based on light penetration, the fundamental difference remains that the photic zone acts as an energy-producing layer, whereas the aphotic zone functions as an energy-consuming environment.1