Introduction. Physical Environment. The Envelope--Shapes, Materials, and Construction. Temperature--Control of Heating and Cooling. Water Composition--The Management of Salinity, Hardness, and Evaporation. Water Motion--Waves, Currents, and Plumbing. Tides--Simulating the Effects of Sun and Moon. The Input of Solar Energy--Lighting Requirements. Substrate--The Management of Rock, Mud, and Sand. Biochemical Environment. Metabolism--Respiration, Photosynthesis, and Biological Loading. Organisms and Gas Exchange--Oxygen, Carbon Dioxide, and pH. Nitrogenous Wastes and Nutrients--Nitrogen, Phosphorus, and the Micronutrients. Control of the Biochemical Environment--Filters, Bacteria, and the Algal Turf Scrubber. Biological Structure. Community Structure--The Framework. Trophic Structure--Ecosystems and the Dynamics of Food Chains. Primary Producers--Plants that Grow on the Bottom. Herbivores--Predators of Plants. Carnivores--Predators of Animals. Plankton and Planktivores--The Floating Plants and Animals and Their Predators. Detritus and Detrivores--The Dynamics of Muddy Bottoms. Symbionts and Other Feeders. Ecological Systems in Microcosms, Mesocosms, and Aquaria. Models of Coral Reef Ecosystems. A Subarctic Shore--The Maine Coast. Estuaries--Ecosystem Modeling Where Fresh and Salt Waters Interact. Freshwater Ecosystem Models. Summary. Microcosms, Mesocosms, and Aquaria as Ecosystem Models--A Synthesis. Index.