What impact does duckweed covering the water's surface have on water clarity during eutrophication?

During eutrophication, an excess of nutrients in the water leads to increased plant growth, including that of duckweed. When duckweed spreads and covers the water's surface, it significantly reduces light penetration into the water. This reduction in light hinders the growth of submerged aquatic vegetation, which is essential for maintaining ecological balance in aquatic systems.

Although the covered water surface may indicate a productive system, the shading effect of duckweed decreases water clarity and the availability of light, resulting in a decrease in the growth of submerged plants. These submerged plants need sufficient light for photosynthesis, and the presence of duckweed creates a competitive environment that ultimately limits their growth, despite existing nutrient levels being high. This relationship emphasizes the negative consequences that can arise from excessive duckweed coverage in eutrophic waters.