The temperature difference may be large enough to hamper mixing with the littoral zone in some seasons which causes a decrease in oxygen concentrations.
[3] The profundal macrofauna is therefore characterized by physiological and behavioural adaptations to low oxygen concentration.
While benthic fauna differs between lakes, Chironomidae and Oligochaetae often dominate the benthic fauna of the profundal zone because they possess hemoglobin-like molecules to extract oxygen from poorly oxygenated water.
[8] The anoxic nature of the profundal zone drives ammonia release from benthic sediment.
Hypolimnetic anoxia can also contribute to buildups of iron, manganese, and sulfide in the profundal zone.