A new technique to increase polyp production in stony coral aquaculture using waste fragments without polyps

The wild harvest of corals for the aquarium trade has had negative impacts on coral reef ecosystems. Although this problem can be directly addressed by increased availability of cultured corals, improvements to current aquaculture techniques are needed to increase coral production. Here, we carried out a manipulative experiment using the large polyp reef-building scleractinian coral Duncanopsammia axifuga to test whether the presence or absence of polyps, the orientation of the fragment's trunk (upside-down or right way up), or heterotrophic diet (unfed, normal Artemia and lipid-enriched Artemia) influences polyp production, growth, survival, and overall health of the coral. There was an 85% survivorship of fragments across all experimental treatments regardless of trunk orientation. D. axifuga produced the highest number of new polyps from fragments initially fixed without polyps, with diet having no effect on polyp production. Conversely, normal and lipid-enriched Artemia diets significantly enhanced growth and polyp production in fragments that were initially fixed with one polyp. Overall, we conclude that D. axifuga is suitable for coral aquaculture purposes due to high survival rates and also because polyp production was successful from what was previously considered waste fragments (i.e. without polyps). Further work is required to determine whether these aquaculture techniques enhance polyp production in other coral species with similar morph types used in commercial aquaculture.