Q. The most productive ecosystem in the biosphere is ____:
Answer: Estuary
Notes: Ecotone regions (transitional zones) like mangroves, wetlands, estuaries, grasslands etc. have high production because of the wide-ranging species from the adjacent ecosystems being present in the ecotone. An estuary has very little wave action, so it provides a calm refuge from the open sea and hence becomes ideal for the survival of numerous aquatic species. Estuaries are most heavily populated areas throughout the world, with about 60% of the world’s population living along estuaries and the coast.