Microcosms and Mesocosms – Restoring Earth’s Ecosystems

by Walter H. Adey, Phd

Microcosms and Mesocosms are aquarium-like tools allowing experimental study of aquatic and wetland ecosystems. In the 1970s, Dr. Adey formed the Smithsonian’s Marine Systems Laboratory to develop a wide variety of constructed experimental ecosystems. Many years of research demonstrated the ability to carry out experiments on functioning ecosystem models in a laboratory setting. These techniques have become ever-more valuable as earth’s ecosystems have become mesocosms framed by human activity, and are treated in depth in Adey,W. and K. Loveland 2007. Dynamic Aquaria, Building and Restoring Living Ecosystems. 3rd. Ed.

Fig. A130 gallon coral reef microcosm after 8 years of closure with its chemical parameters controlled solely by an algal turf scrubber. This system, studied by a multidisplinary team of biologists, demonstrated calcification rates equal to the best 4% of wild reefs and at 543 identified species, and an estimated 800 species, ranked per unit area as the most biodiverse reef ever measured. Fig. BClose up of 130 gallon coral reef microcosm shown in Fig. A. Every square cm is occupied with living organisms. 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 95% of the identified species in this microcosm maintained their populations through reproduction; most of these species pass through a planktonic state of several days to a month during reproduction.
Fig. CTridacna (giant clam) that entered the microcosm as a half-dollar sized young specimen and eventually grew about 40 cm in length before it had to be transferred to a larger system. Fig. D   (click to enlarge)Oxygen and pH curves in 3000 gallon coral reef exhibit mesocosm as compared to its wild analog on St. Croix in the Caribbean. Along with calcification, metabolism and biodiversity, these parameters are used to match microcosm and mesocosm coral reefs to their wild analogs.
Fig. EFlorida 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. This is a large Archimedes Screw. Fig. F   (click to enlarge)Schematic diagram of the Florida Everglades Mesocosm (high salinity unit shown to right, fresh water to left, and estuarine units between). Tide ranges in each unit are shown; they were set to the mixed semidiurnal/diurnal tide characteristic of southwest Florida. The entire estuarine system operated as a dynamic unit for over ten years.

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