Microcosms and Mesocosms– Restoring earth’s ecosystems

Every square cm is occupied with living organisms in a 130-gallon tank. Yellow spot to the upper right of the snail in the center is a young Porites asteroides coral that has settled in the tank as a result of successful sexual reproduction. Better than 90% of the identified species in this microcosm maintained their populations through reproduction, most of which passed through a planktonic state.

Microcosms and Mesocosms are aquarium-like tools allowing experimental study of aquatic and wetland ecosystems. Many years of research in the Smithsonian Marine Systems Laboratory with a wide variety of constructed ecosystems has demonstrated the ability to carry out experiments on functioning ecosystem models in a laboratory setting.

Simulating natural ecosystems to better understand and restore our waters

130 gallon coral reef microcosm after 8 years of closure with its chemical parameters controlled solely by an algal turf scrubber. This system demonstrated calcification rates equal to the best 43% of wild reefs and 543 identified species, and an estimated 800 species (although 25 scientists participated in this study, some invertebrate groups were not identified due to the lack of a specialist), ranks per unit area as the most biodiverse reef ever measured (2001).

Portion of the experimental coral reef showing the stony head coral Diploria cavernosa (center), a gorgonian (right), and a clownfish.

A comparison of calcification rates between pan-tropic coral reefs and experimental coral reefs reveals that the latter exhibit calcification rates exceeding those of over 96% of wild coral reefs. Notably, two stony coral genera studied in this research, Acropora and Montipora, demonstrated calcification rates higher than any previously reported in the scientific literature up to 2001. These findings highlight the exceptional growth potential of these corals under experimental conditions, suggesting valuable insights for coral reef conservation and restoration efforts.

Figure E. Florida Everglades Mesocosm.jpg

Florida Everglades Mesocosm in a Washington, D.C. greenhouse. At the lower right is the coastal salinity section with the red mangrove estuarine unit behind. The end of a 4 unit, 6m² Algal Turf Scrubber shows at the lower left while the diagonal green tube above is the primary water driver, a large Archimedes Screw.

Diagrammatic sectional view of the FEM showing the hydraulic components (piping, pumps, RO, ATS units, saltwater and freshwater, tide controller, tidal ranges). To save space, highly limited even in a large greenhouse, the estuary was utilized as the tidal reservoir; tidal phases alternated between the coastal tank and the estuary. At spring high tides in the coastal tank (spring low tide in the estuary), a gate valve was opened between the two systems for several hours to allow mobile organisms to transit between the two systems.