Producers
Autotrophs (self-nourishing) are green plants as they synthesise carbohydrates from simple inorganic raw materials like carbon dioxide and water in the presence of sunlight by the process of photosynthesis for themselves, and indirectly for other non-producers. In terrestrial ecosystem, producers are basically herbaceous and woody plants while in marine and fresh water ecosystems producers are various species of microscopic algae. Chemosynthetic bacteria are also producers. However, unlike plants which constitute the major producers, these bacteria, which are found in deep ocean trenches where sun energy is absent, derive energy by the process of chemosynthesis from the hydrogen sulphide seeping through cracks in the sea floor.