A materially-closed aquatic-ecosystem: a useful tool for determining changes of ecological processes in space.

A materially-closed aquatic ecosystem (microcosm) was developed. The microcosm contained two families of green algae and blue-green alga as primary producers, protozoa, two species of rotifers and oligochaetes as consumers, and bacteria as decomposers. The microcosm could be readily replicated. It was confirmed the population densities of each organism were almost constant for 365 days without artificial operation except temperature and light. The population dynamics and the spatial patterns of the organisms were simulated by mathematical models. This hermetically-sealed microcosm could be a useful subject to investigate ecology under space environment.