Clams in Space
Giant clams would be an excellent organism to study for their ability to grow in their seawater environment on the Space Station, at least for the initial trials. If 'seed' clams (from 0.7 - 10 mm) can be grown successfully in plexiglass containers filled with seawater (with associated small recirculation system) then there is the potential for the use of giant clams in a Moon Station.
Giant clams are 'solar animals' because they act as a host for symbiotic dinoflagellate algae termed 'zooxanthellae'. They are 'infected with the zooxanthellae each generation and the algae upon ingestion are moved into tubules emanating from the stomach. These tubules divide many times and fill the spaces close to the mantle tissue surface. During sunlight the zooxanthellae photosynthesize like any good plant and the byproducts are the simple sugars, some amino acids, and oxygen. The clams utilise this food and the excess oxygen is shunted out the gills during daylight hours. What better organism than this for a joint traveller with us in space!
Imagine a Moon Station which is partially built underground to protect from meteorites. There may be an opening to a 'cave' which looks out over the moonscape to view an earthrise. The cave opening would be an excellent area to use for a series of clear plexiglass windows which would enclose a marine garden and aquaculture section. The light of the sun could be best utilised for these phototrophic animals through such a window. Outside the cave entrance there may be a monitor to sense impending meteorites or dust which may damage the window. A metal door would close automatically outside of the window when the monitoring mechanism detects potential trouble.
Although this is only but a fanciful dream at this time, it is nevertheless a practical dream because any Moon Station will have to rely partially on culture of food there at the Station.
Just something to think about and realise that it is just possible enough that we must do something about it. What better organism to work on than the largest bivalve mollusc the planet has ever seen, and one that has won in the genetic gamble of ultilising the symbiotic relationship with the zooxanthellae dinoflagellate algae to its greatest advantage allowing this bivalve to reach such a large body size. During the ACIAR-funded Giant Clam Project of the mid-80s to early 90s, the production rate of this species (Tridacna gigas) was found to be over 25 tonnes per hectare per year. That is really good when compared with cattle production on good grassland, and better yet that the clams are not fed, but mainly require nutrients (N, P) to supply to their zooxanthellae like one would go out and buy fertiliser for one's garden. I submitted a proposal to NASA around 1990 to do experiments using small seed clams on the then proposed Space Station. The proposal was initially sent to Sen. John Glenn, as I had met him many years ago in Honiara, Solomon Islands during its Independence Celebrations . He forwarded the proposal to NASA. A typical answer came from someone who did not properly read the proposal, saying that NASA had to be concerned about weight and space. They obviously assumed we planned to send one of the 'old fellow' clams! Nevertheless, it is worthy of consideration to be included in such a long-term plan.
Updated 26 May 2016; Copyright © Aquasearch