Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?

Ecosystem productivity is measured by Net Primary Productivity (NPP), the rate at which solar energy is converted into organic matter. Mangroves are among the most productive ecosystems globally, acting as nutrient traps that export energy to adjacent communities [4]. Grasslands follow, as they possess high biomass turnover despite lower structural complexity than forests . Lakes generally exhibit lower productivity than terrestrial grasslands, though this varies with nutrient levels (eutrophic vs. oligotrophic) . Oceans, while contributing significantly to global carbon cycles due to their vast area, have the lowest productivity per unit area (averaging 350 dry grams/m²/year) because large portions are nutrient-poor 'biological deserts' [4]. Therefore, the correct decreasing sequence is Mangroves, grasslands, lakes, and oceans .

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 4: BIODIVERSITY > MAngrove (forests). > p. 49
2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 4: BIODIVERSITY > Biogeographic zones of India > p. 26
3. [4] https://www.nature.com/articles/s41597-025-05773-4