What major threat does deforestation pose to water quality in the Amazon?

Deforestation significantly affects water quality in the Amazon primarily by increasing sedimentation and turbidity. When trees are cut down, the soil that was previously held in place by roots can easily erode. This erosion leads to run-off, which carries sediments into nearby rivers and streams. As more sediment enters the water, it results in higher levels of turbidity, which can disrupt aquatic ecosystems.

Increased turbidity can hinder the ability of aquatic plants to photosynthesize, impair fish gills, and reduce feeding opportunities for certain aquatic organisms that rely on clear water. The disruption of these ecosystems not only impacts the immediate environment but can also lead to long-term changes in water quality, affecting everything from nutrient levels to the overall health of aquatic species.

The other options do not accurately reflect the impacts of deforestation on water quality. For instance, instead of improving water temperature, deforestation typically leads to increased water temperatures due to the loss of shade provided by trees. Likewise, while deforestation does not enhance aquatic vegetation, it adversely impacts their growth due to increased sedimentation. Finally, rather than supporting diverse fish populations, the negative effects on water quality can lead to declines in fish populations, highlighting how interconnected these environmental issues are.