All organisms carry out each of the ecosystem processes to some extent. Production refers to the rate of incorporation of energy and materials into the bodies of organisms. Consumption refers to the metabolic use of assimilated organic molecules for organismal growth and reproduction. Decomposition is the breakdown of organic molecules into inorganic molecules. The main primary producers will vary depending on the ecosystem.
Plants are the main producers in most terrestrial ecosystems.
Multicellular algae and aquatic plants are often more important primary producers in the shallow, near-shore areas of freshwater and marine ecosystems. Organisms in communities surrounding the hot water vents on the deep-sea floor depend more on chemical energy than solar energy. The main producers are chemoautotrophic bacteria that derive energy from the oxidation of hydrogen sulfide. C. Many primary and higher-order consumers are opportunistic feeders Consumers also vary with the type of ecosystem. Primary consumers are considered opportunistic because they supplement their diet of autotrophs with heterotrophic material if it is available.