Ecosystem Productivity Sequence

The correct sequence of ecosystems by decreasing productivity is: Mangroves > Grasslands > Lakes > Oceans. Mangroves have the highest productivity due to their high nutrient availability and dual inputs from land and water systems. Grasslands have high productivity due to good sunlight, available nutrients, and efficient solar energy capture. Lakes (freshwater) are moderately productive, while oceans, despite being vast, have lower overall productivity per unit area because much of the ocean is nutrient-poor. This sequence reflects net primary productivity (NPP) values measured in grams per square meter per year. Option (a) incorrectly places oceans first and mangroves last. Option (b) reverses some elements. Option (d) also misorders the sequence. > Mangrove > Grassland > Lake > Ocean: Remember mangroves as the most productive ecosystem due to dual nutrient inputs. Answer: (c).