Coral Reefs Create Clouds to Control the Climate
My main point: coral is not efficient. If we take the effort to transplant coral and let it proliferate on the way to a star system, we could also take the effort to create a Neumann machine that will continuously duplicate itself on the way there, creating a couple of million DMS synthesis stations. Whether we use coral or Neumann machines, we are reliant on technology for success anyway. Attaching some synthesis station to a transportation vehicle seems more viable to me, especially when you think of all the machines that have to wine&dine, nurture and cuddle the coral. Furthermore, certain algae and prokaryotes are known to produce more efficiently/of the DMS that is required. Their need for 'cuddling' is slightly less apparent.
I estimate we both go on and on slinging 'facts' at each other about feasibility of coral-terraforming and the success of sex-selection through PGD, but that really is not the issue. Hence my earlier cynical undertone earlier: the original message is lame.
For all we know, we can use DMS-producing coral in the future to boil our eggs without even putting them into water. Or we can plant coral in the sahara to save all africans from certain starvation by generating rain through DMS-generated clouds. Analogy: with all the nice research going on, I think there will be better and more viable options to save the Africans and boil eggs without water.
But no, I don't know whether this can be achieved through one mechanism only. Wait a minute, we can! Drop a thousand eggs on the sahara and let them bake in the sun: salmonella-free and nutritious and no water used..
Apart from "you never know", that's all I'm gonna say for now. :)