Lipid Composition Of Gametes In Scleractinian Reef-Building Corals: Wax-Esters Generate Buoyancy For The Gametes

Most reef-building corals are hermaphroditic and discharge buoyant bundles that contain a mixture of eggs and spermatozoa during the breeding season. The buoyancy of the bundles is due to wax-esters. This study analysed and compared the lipid compositions in eight species of corals. Overall, 60-80% of the total lipid composition of the eggs or embryos of six species,Acropora digitifera, A. florida, A. monticulosa, Dipsastraea lizardensis, Ctenactis echinata, andPseudosiderastrea tayamaithat discharged buoyant eggs was wax-esters. AlthoughGalaxea fascicularisis a dioecious coral, the bundle released from males (or hermaphrodites) contained spermatozoa and pseudo-eggs. Both eggs and pseudo-eggs contained high amounts of wax-esters. In contrast, the wax-ester content in sedimenting eggs released fromOulastrea crispatawas very low. Thus, this study confirmed the presence of wax-esters in buoyant egg bundles. This suggests that wax-esters play a role in the dispersal and settlement potential of planula larvae in corals.