What is a direct consequence of nitrate runoff on aquatic ecosystems?

What is a direct consequence of nitrate runoff on aquatic ecosystems?

• A. Improved water quality due to lower nutrient loads
• B. Water becomes less productive for algae
• C. Decreased algae growth and higher oxygen levels
• D. Algal blooms and oxygen depletion in water bodies

Answer: (D)

Nitrate runoff acts like fertilizer for algae in water bodies, sparking rapid growth known as algal blooms. When these blooms become dense, they can block light and disrupt the ecosystem. As the algae die, decomposers break down the organic matter, using up dissolved oxygen in the water. That depleted oxygen creates low-oxygen conditions that stress or kill fish and other aquatic life. So the direct consequence you’d observe is algal blooms followed by oxygen depletion in the water.