What is a primary consequence of high biochemical oxygen demand in a water body?

High biochemical oxygen demand (BOD) in a water body indicates a significant amount of organic matter that microorganisms will break down through respiration. This process consumes oxygen from the water, leading to a reduction in dissolved oxygen levels. Aquatic organisms, particularly fish and invertebrates, rely on dissolved oxygen for survival. When BOD levels are high, the oxygen depletion can result in hypoxic or anoxic conditions, severely impacting aquatic life by reducing the available oxygen necessary for respiration. Consequently, the primary consequence of high BOD is indeed the reduction of oxygen for aquatic organisms, which can lead to dead zones and a decline in biodiversity. This is crucial for maintaining the health of aquatic ecosystems.