Which term describes the cold deep layer with low oxygen?

Which term describes the cold deep layer with low oxygen?

• A. Epilimnion
• B. Hypolimnion
• C. Nekton
• D. Plankton

Answer: (B)

In lakes that stratify, water forms distinct vertical layers. The upper, sun-warmed layer is the epilimnion, which is typically warm and rich in dissolved oxygen due to contact with the air. Beneath it lies the cold, deep layer—the hypolimnion. This layer stays cold because it is far from the sun’s heat and experiences little mixing with the surface; oxygen can become low there because respiration and decomposition consume what’s available and there’s limited replenishment from the air. So the cold deep layer with low oxygen is the hypolimnion. Nekton and Plankton are organisms, not layers, and the epilimnion is the warm surface layer.

In lakes that stratify, water forms distinct vertical layers. The upper, sun-warmed layer is the epilimnion, which is typically warm and rich in dissolved oxygen due to contact with the air. Beneath it lies the cold, deep layer—the hypolimnion. This layer stays cold because it is far from the sun’s heat and experiences little mixing with the surface; oxygen can become low there because respiration and decomposition consume what’s available and there’s limited replenishment from the air. So the cold deep layer with low oxygen is the hypolimnion. Nekton and Plankton are organisms, not layers, and the epilimnion is the warm surface layer.