What is the potential ecological impact of heightened duck populations in aquatic areas?

The correct answer highlights a significant concern regarding increased duck populations in aquatic ecosystems—namely, their potential to decrease water quality due to coliform bacteria. As duck populations grow, their droppings can lead to heightened nutrient levels in the water, specifically nitrogen and phosphorus, promoting the growth of harmful bacteria such as coliforms. These bacteria serve as indicators of fecal contamination, which can degrade water quality and impact other organisms, including fish and plants, in the ecosystem.

Healthy aquatic environments typically have a balanced microbial community, but a surge in pollutants from duck waste can disrupt this balance. Elevated coliform bacteria levels can pose health risks to humans and wildlife alike, making it a serious ecological concern that can affect recreational activities and ecosystem integrity.

Increased fish populations, enhanced plant growth competition, and a reduction in aquatic plant diversity are all potential impacts of duck populations, but they reflect indirect consequences rather than the more immediate and pressing issue of water quality degradation caused by bacterial contamination.