Why are rivers generally less productive than swamps in terms of primary productivity?

• A. Swamps have lower biodiversity, which increases their productivity.
• B. Rivers have higher concentrations of dissolved oxygen, which inhibits plant growth.
• C. Rivers receive more sunlight than swamps, limiting photosynthesis.
• D. Rivers have faster-moving water, which reduces the accumulation of nutrients and organic matter needed for high productivity.

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. It is influenced by factors such as nutrient availability, sunlight, and environmental conditions.
2. Compare the environmental conditions of rivers and swamps: Rivers typically have faster-moving water, while swamps are characterized by stagnant or slow-moving water. This difference in water movement plays a key role in nutrient accumulation and organic matter retention.
3. Analyze the impact of water movement on nutrient availability: Faster-moving water in rivers tends to wash away nutrients and organic matter, preventing their accumulation. In contrast, the slow-moving water in swamps allows nutrients and organic matter to settle and accumulate, creating a nutrient-rich environment.
4. Consider the role of nutrients in primary productivity: Nutrients like nitrogen and phosphorus are essential for plant growth and photosynthesis. The nutrient-rich environment of swamps supports higher primary productivity compared to rivers, where nutrients are less concentrated due to constant water flow.
5. Conclude why rivers are less productive: The faster-moving water in rivers reduces the accumulation of nutrients and organic matter, which are critical for high primary productivity. This explains why rivers are generally less productive than swamps.