autotrophic organisms are producers that generate organic compounds from inorganic material. algae use solar energy to generate biomass from carbon dioxide and are possibly the most important autotrophic organisms in aquatic environments. the more shallow the water, the greater the biomass contribution from rooted and floating vascular plants. these two sources combine to produce the extraordinary production of estuaries and wetlands, as this autotrophic biomass is converted into fish, birds, amphibians and other aquatic species.