GFP distribution and fluorescence intensity in Galaxea fascicularis: developmental changes and maternal effects

Scleractinian corals exhibit various colors depending on the host fluorescent proteins and non-fluorescent chromoproteins. It is not understood whether the color patterns are determined genetically or influenced by the environment. We performed breeding experiments between green (Gs) and brown (B) color morphs of Galaxea fascicularis, wherein Gs morphotypes have much higher green fluorescent protein (OFP) content than that of B morphotypes. Larvae that developed from B morphotype eggs showed significantly higher average OFP fluorescence intensity per polyp area than those from Gs morphotype eggs, regardless of paternal morphotypes. Similarly, juveniles derived from B × B crosses showed higher fluorescence intensity than those derived from G_s × G_s crosses. The OFP pattern changed after settlement in that it increased in concentration around the mouth. No difference was observed among crosses. This is the first study to show a possible maternal effect on OFP intensities in coral larvae and juveniles.