What is a major consequence of sediment pollution from construction sites?

Sediment pollution from construction sites significantly contributes to reduced oxygen levels in aquatic environments. When sediments enter water bodies, they can settle on the bottom and create a layer that inhibits the growth of aquatic plants and essential organisms. This sediment layer can block sunlight, leading to decreased photosynthesis and a reduction in oxygen produced in the water.

Additionally, when sediments carry nutrients and organic matter, the increased availability can lead to algal blooms. As these algae die and decompose, the respiration processes that occur consume dissolved oxygen in the water, further compounding the issue of low oxygen levels. This situation can create "dead zones," where insufficient oxygen makes it difficult for aquatic life, particularly fish and invertebrates, to survive.

In contrast, the other options portray outcomes that are contrary to the effects of sediment pollution. For example, increased water clarity and improved water quality would typically not result from sediment pollution; instead, these conditions would arise from effective management practices that reduce sediment runoff. Enhanced fish populations also tend to decline in the presence of high sediment levels due to the adverse effects on their habitats and food sources. Thus, reduced oxygen levels accurately characterize a major consequence of sediment pollution from construction activities.