Studies in Closed Ecological Systems: Biosphere in a Bottle

Small closed ecological chambers are an efficient model for developing principles of bioregenerative systems. Knowing these principles can enhance long distance space travel and remote human habitation. Closed systems were constructed in the laboratory using tissue culture flasks and one-liter glass bottles. All nutrients, micro algae and aquatic macro-invertebrates were added approximately one week before sealing. Viability of the closed system was judged by continued survival and activity of macro- invertebrates. Teams studied varying light intensity, nutrient concentration, temperature and varying air space. We found that Tigriopus californicus (a salt water copepod detritus feeder) populations maintained a steady abundance at high intensity light, increased quickly at moderate light and declined quickly at low light. Daphnia magna (a fresh water zooplankton) population increased more rapidly at high temperature. Within the levels of nutrient concentration we tested, T. californicus population growth increased with more algal nutrients. While trying to test the relationship between air space and viability, we observed that when refuges were present for algae and macro- invertebrates, populations outlived those without refuge space. Studies are continuing.