The coral cliff hanger..

Working with biology is always funny. You can't really predict anything and as soon as things start to look good, life chooses another way and will mess everything up. It's the curse of biological experiments but also what makes it really fascinating and interesting to work with!

Something like that happened to my corals right after we added the different water treatments to the aquariums. After 24 hours in treated water, the coral fragments of species Acropora decided that life wasn't worth living anymore. Specially in one of the aquariums, they seemed to have planned a coordinated suicide demonstration. All of them were bleaching!

Bleaching event

A quick basic recap for those of you who might be unfamiliar with coral bleaching: Corals have a symbiotic relationship with a tiny little phytoplankton (Dinoflagellates) most commonly called zooxhantelleas. The zoox live in the coral tissue where they can photosynthesis giving the coral energy. In return the coral provides a safe refuge and essential nutrients. A nice win-win for both. However, if the coral is stressed it can expel the zoox - it will bleach! This can be fatal for the coral, but it is also possible for them to recruit new zoox and recover. 

 If this bleaching really was a result of our water treatment, that would be a very interesting and quick response! However, it seemed that only one aquarium was heavily affected.
To try to save the poor little things we moved them back to a control tank. Then added three new fragments in the affected aquariums and left them overnight to see if the same response would happen. We added more shade to the aquariums since the Acropora sp. can be very sensitive to light - maybe the combination of treated water and light was the problem?

Healthy Acropora.

Bleached Acropora

The next day the new test fragments looked fine. Our conclusion: the light intensity had been too high. I then spent the day chipping off new fragments to replace the bleached ones and got all the coral fragments back into the aquariums with the treated water.

They have now been there for a few days and the look to be surviving.
Experiment back on track !