Which of the following ecosystems is most productive?
Estuaries rank among the most productive ecosystems per unit area because river water supplies nutrients and organic matter while tides mix them with coastal seawater. Shallow depths permit substantial light penetration, and tidal circulation repeatedly redistributes oxygen and nutrients rather than allowing resources to remain isolated. Salt marsh plants, mangroves, seagrasses, benthic algae, and phytoplankton may all contribute primary production, while detrital food webs efficiently process plant material. Estuaries also trap sediments and nutrients at the land-sea boundary, supporting dens
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 2-3