Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?
Smart Elimination
Think about the maximum productivity which you could do in per unit area. Here, open Oceans are 'biological deserts' with very low productivity per unit area. Thus the sequence must end with Oceans.
At the same time, Mangroves offer more productivity per unit area.
Identifying both these would ensure that we land at option (c)
Potential Trap
Thinking Oceans are highly productive. While total production is high due to size, productivity *per unit area* is very low.
Answer Key & Explanation
Answer: CThe correct answer is Option C.
Explanation: Productivity is defined as the rate of biomass production (grams per square meter per year).
- Mangroves/Estuaries: Very high productivity due to nutrient trapping and shallow waters. (~2000-4000 g/m²/yr)
- Grasslands: Moderate productivity. (~500-1000 g/m²/yr)
- Lakes: Variable, but generally less than wetlands/swamps.
- Oceans: Open oceans have very low productivity (comparable to deserts) due to lack of nutrients in surface waters, despite their vast size. (~125 g/m²/yr)
Order (Decreasing): Mangroves > Grasslands > Lakes > Oceans.
Value Addition
- Coral Reefs: Also have very high productivity.
- Deserts: Lowest productivity.
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Foundational question based on core concepts.