From: utzoo!henry Newsgroups: net.space Title: closed ecosystems Article-I.D.: utzoo.2116 Posted: Tue Jun 1 22:51:39 1982 Received: Tue Jun 1 22:51:39 1982 One of the objections raised to the space-colony concept has been the total lack of understanding of how to run closed-cycle ecosystems. Attempts at creating simple closed systems that are self-sufficient in water and nutrients (not just oxygen) haven't been too successful so far. A report in the May issue of JBIS indicates that this situation has now changed. Fifteen months ago, JPL ecologist Joe Hanson prepared a number of small ecosystems consisting of one-liter flasks containing imitation seawater, assorted algae, numerous microorganisms, and inch-long tropical shrimp. The necks of the flasks were then fused shut, sealing the systems off completely from the biosphere: only light and heat get in or out. The little ecosystems are doing quite well. In a few the shrimp have died, but in most they are thriving. The algae are healthy even in the flasks with no shrimp left, suggesting that microorganisms are supplying carbon dioxide. There are other differences between various flasks; for example, different algae species are dominant in different flasks, although they all started with pretty much the same mix. The reasons for these differences are not well understood. Hanson is now trying to figure out non-invasive ways of measuring what is going on in the flasks. If this problem can be solved, these long-lived "microecosystems" may be a major breakthrough in the science of ecology, permitting controlled and repeatable experiments on whole ecosystems for the first time. The thing I find most interesting about his technique is that the stable ecosystems did not arise out of systematic planning, with a small number of species and carefully-planned interactions and cycles. I have long thought that the way to get a space colony's ecosystem going is just to transport a slice of Earth's biosphere and let it adjust to the new environment by itself.