Ecosystem of a Small Pond

           The system operates on solar energy and the producers are a community of green plants  which include free-floating phytoplankton, algae, grasses and other plants surrounding the pond.   Abiotic base material, for supporting the producers, is provided by the water, salts, and carbon dioxide of the pond and by the organic detritus that falls to the bottom.  Primary consumers are small crustaceans and other herbivores such as mollusks and annelids that feed directly upon the producers.  The secondary and tertiary consumers are small and larger carnivorous species such as fish and some birds.  The decomposers, which prevent a large accumulation of organic matter, are made up of the community of fungi and bacteria that mainly inhabit the bottom sediment.