Fertilizer runoff has a negative impact on aquatic ecosystems because _______.

Fertilizer runoff adds excess nutrients, including phosphorus and nitrogen, to waterways. These nutrients can cause plants and algae to grow rapidly; when they die and decompose, oxygen levels in the water can fall, harming or suffocating aquatic organisms. So the correct choice is “it causes plants and algae to grow quickly, suffocating organisms in the water.”

AI-written and checked against the verified answer.