'Symbiont-switching: too optimistic'

Responding to Andrew Baker ('Inoculation: not a cure-all but worth trying') and others, Tom Goreau writes:

I completely agree with Andy Baker that we need to try all we can and hope it works. But I don't share his optimism because almost all corals are really much fussier than he seems to acknowledge about the very precise strain of zooxanthellae they will take up, expel the rest, and don't seem to have much rapid ability to adapt. That has been known for a very long time from the work of Bob Trench and his students. [See also a] recently published great paper by Tamar Goulet. One could be left with only a handful of very unusual corals if Andy is right.

My own view for about 20 years is that it has long been clear from field observations (going back more than 20 years) that susceptibility and resistance to bleaching have genetic components. We therefore need intensive genetic research into understanding exactly which genes and proteins are involved in both thermal stress susceptibility and resistance, and the effects of inducing or repressing their activity. This takes a state of the art laboratory and committed team. The next step is to grow all the variants one can with all the zooxanthellae one can get them to hold on to and all the genetically engineered corals and zooxanthellae in which the variants of the key genes and enzymes are expressed. This needs a huge state-of-the-art coral growing facility.

What is also needed, and which only we can do, is to grow them all on Biorock at faster growth rates, see how they respond to severe bleaching, select the survivors, see how their genes and protein expression may be different, propagate them, and see how they respond to the next bleaching event, etc.

Note: Andrew Baker and Andrienne Romanski commented on Goulet's paper in Multiple symbiotic partnerships are common in scleractinian corals, but not in octocorals (April 2007).