The microorganisms that inhabit the sludge at the bottom of a lake would live in which microbiota zone

Explanation:

In a lake, oxygenic phototrophs produce new organic material as  well as O₂. If primary production rates are very high, the resultant  excessive organic matter production can lead to bottom-water O₂ depletion from respiration and the development of anoxic conditions.  This in turn stimulates anaerobic metabolisms, including  anaerobic respirations and fermentations.

Organic matter that is not  consumed in surface layers sinks to the depths and is decomposed  by anaerobes.

rocks and weathering-matching

because the light is a great source of energy for the plants to survive. (i hope this )