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.