Lipid composition of coral propagules and reproductive material in coral restoration nurseries

Coral restoration efforts have rapidly increased worldwide, including the development of several programmes on the Great Barrier Reef (GBR) in recent years. While many restoration programmes utilise in-water nurseries to accelerate coral biomass yields, the impact of nursery environments on propagule quality has not been examined despite the importance of coral fitness for ensuring resistant populations. Here, we investigated two fitness indicators (lipid diversity and tissue protein abundance) of Acropora millepora adults and eggs grown on coral nurseries versus native reef on the GBR, with adults assessed at two sites (Blue Lagoon and Rayban) and eggs assessed at one site (Blue Lagoon). Lipid profiles of adult colonies varied by site and origin (nursery versus wild reef), with adult nursery corals exhibiting an elevated relative abundance of storage lipids (diacylglycerols and triacylglycerols) and lipid classes responsible for regulating membrane structure (phosphatidylcholines and sterol esters), while wild corals were characterised by a greater relative abundance of fatty acids and classes involved in immunoregulation. Comparing eggs from different origins, nursery offspring were richer in energy-storing triacylglycerols, as well as ceramides and phosphatidylcholines essential for membrane structure, while wild eggs had a greater relative abundance of wax ester species also important for energy storage. No differences were found in total protein abundance (adult or eggs) or egg physical characteristics (count and size) between nursery and wild origins. Variations in lipid profiles are consistent with differences in environmental conditions between reef sites and origin (nursery versus wild), highlighting the need to consider site selection and propagation conditions when planning restoration projects. Importantly, these findings demonstrate that the lipid classes with the highest relative abundance in A. millepora nursery and wild eggs differed from those in adults from the same origin, suggesting that propagation origin is more important for driving lipid profiles in coral eggs compared to parental effects.