What happens at the compensation depth in a lake?

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lake Lake Ann in North Cascades National Park, Washington, U.S., viewed from the park's Maple Loop Trail. The North Cascades National Park is a large wilderness area that preserves majestic mountain scenery, snowfields, glaciers, and other unique natural features.

At the compensation depth in a lake, the light intensity is such that the energy produced through photosynthesis is exactly balanced by the energy consumed through respiration.12

This depth serves as a critical ecological boundary:

Euphotic Zone: Above this depth, primary production exceeds consumption, allowing for the growth of phytoplankton and other primary producers.12
Aphotic Zone: Below this depth, consumption exceeds production, meaning that phytoplankton cannot survive unless they are capable of vertical migration.12

Because this balance depends on light penetration, the compensation depth is not fixed; it varies diurnally and seasonally based on environmental factors.2