I am not familiar with the term, but have found it in a dictionary and used in the same way in one Ghit.
"cosms :
Artificial ecosystems of various levels of complexity and scale. See also macrocosm; mesocosm; microcosm. [P.C.]"
Found this from The Encyclopedia of Ecology and Environmental Management, Blackwell Science via http://www.xreferplus.com/

Used mant times in this ref: http://www.nrcan.gc.ca/ms/canmet-mtb/mmsl-lmsm/enviro/report...
Here are a couple of examples:
"Problems with cosm experiments"
"Cosms are simple communities that might be as large as a pond,
or as small as an aquarium or a dish. As a generalization, cosms in containers in a laboratory yield results that are variable and difficult to interpret, making them difficult for toxicity validation"
"Perhaps the best correspondence between lab and cosm was obtained by Larsen"