Generally in the food chain of the terrestrial and aquatic ecosystem the largest population is that of:
Producers
Generally, in the food chain of the terrestrial and aquatic ecosystem, the largest population is that of producers. The number of organisms in each trophic level of a food chain depends upon the availability of food and energy. As producers form the base of the energy pyramid, they are generally more in number. And since energy is lost at each trophic level as heat, the pyramid tapers, indicating a reduction is biomass and hence numbers as you go up the levels.