The degradation of biomass derived from aquatic organic matter leads to what change in dissolved oxygen levels?

The degradation of biomass, particularly from aquatic organic matter, typically leads to a decrease in dissolved oxygen levels in the water. This process is primarily driven by microbial activity, where bacteria consume the organic matter. As they metabolize the biomass, they use oxygen for respiration, which reduces the overall concentration of dissolved oxygen in the water body.

When organic matter breaks down, the demand for oxygen increases significantly due to the respiration of aerobic microorganisms. These microorganisms thrive in environments where organic matter is plentiful, but their oxygen consumption can significantly deplete the available dissolved oxygen. In aquatic ecosystems, this process can have serious implications, such as leading to hypoxic conditions (low oxygen levels) that can be detrimental to fish and other aquatic organisms.

The reduction in dissolved oxygen due to this biological activity is critical in understanding the health of aquatic systems and managing water quality, as low oxygen levels can lead to fish kills and loss of biodiversity. Therefore, the correct answer indicates the direct impact of biomass degradation on dissolved oxygen levels.