What effect do large amounts of decomposing plants have on dissolved oxygen levels in water?

Large amounts of decomposing plants have a significant impact on dissolved oxygen levels in water by lowering them. This occurs because the decomposition process is carried out by microorganisms, which consume dissolved oxygen as they break down the organic matter. As these bacteria and other decomposers metabolize the plant material, they deplete the available oxygen in the water, leading to reduced levels of dissolved oxygen.

When dissolved oxygen levels drop, it can create stressful conditions for aquatic life, particularly for fish and other organisms that rely on oxygen for survival. Thus, the presence of large amounts of decomposing plant matter can dramatically affect the overall health of the aquatic ecosystem.