You’ve heard of mini reefs, nano reefs, pico reefs, femto reefs but forget about all that because scientists have just taken the title of the world’s smallest coral aquarium. The coral-on-a-chip is the smallest possible live aquarium environment consisting of a single polyp housed in barely more than a few drops of water in a microscope slide!
Researchers studying the calcification and bleaching response of several coral species by micropropagating Pocillopora damicornis into tiny frags, and then inducing individual polyps to bail out by gradually exposing them to higher and higher salinities. The single polyps of Pocillopora have plenty of room to grow and settle in the 3mm diameter chamber of the coral-on-a-chip.
The coral-on-a-chip system has inlet and outlet chambers that flow water through at the astonishing minute flow rate of 1 milliliter per hour! The entire coral-on-a-chip assembly is maintained in line with a larger body of water which is kept at specific temperature, using a 25 watt fixed temperature Aqua Medic heater.
Using this microfluidic system scientists have observed the calcification rate of Pocillopora damicornis under differing environments, and they’ve even induced bleaching in the corals. The corals were kept under a nominal lighting intensity of 150 umols of PAR, but to induce bleaching the corals were exposed to very bright lighting of 2,500 umols for six hours, or 1,500 umols for 12 hours.
The world’s smallest coral reef aquarium was created to study in vitro reactions of corals to various environmntal stimuli, but it is documented in a paper mainly to share the method by which the coral-on-a-chip is created. There are so many things we would like to do with our own tiny coral aquarium, but then we’d have to use a microscope to see any of the action.
The coral-on-a-chip microfluidic coral ‘aquarium’ concept is described in the newest edition of Nature by Shapiro et. al.