Which of the following is a possible cause for a decrease in ecosystem primary productivity?

• A. Increased nutrient input
• B. Optimal temperature conditions
• C. Abundant water supply
• D. Reduced availability of sunlight

Answer: (D)

Verified step by step guidance

1. Understand the concept of primary productivity: Primary productivity refers to the rate at which plants and other photosynthetic organisms produce organic compounds (like glucose) from carbon dioxide and water using sunlight as an energy source.
2. Recognize the factors affecting primary productivity: Key factors include sunlight availability, nutrient levels, water supply, and temperature conditions. These factors influence the ability of photosynthetic organisms to perform photosynthesis efficiently.
3. Analyze the options provided: Increased nutrient input, optimal temperature conditions, and abundant water supply are all factors that typically enhance primary productivity. Reduced availability of sunlight, however, directly limits photosynthesis, as sunlight is the primary energy source for this process.
4. Relate sunlight availability to photosynthesis: Photosynthesis relies on light energy to drive the conversion of carbon dioxide and water into glucose and oxygen. Reduced sunlight availability decreases the energy input, thereby lowering the rate of photosynthesis and primary productivity.
5. Conclude that reduced sunlight availability is the correct answer: Among the options provided, reduced sunlight availability is the only factor that would cause a decrease in ecosystem primary productivity, as it directly limits the energy source required for photosynthesis.