Species-specific variation in the metabolomic profiles of Acropora hyachintus and Acropora millepora mask acute temperature stress effects in adult coral colonies.

Coral reefs are suffering unprecedented declines in health state, on a global scale. Some researchers suggested that human assisted evolution (HAE) or assisted gene flow (AGF) may be necessary in order to effectively restore reefs and pre-condition them ready for the change in climate. To fully deploy such approaches, an omic-scale understanding of proposed transplanted corals would ensure desirable end benefits are achieved i.e. increased thermal resilience in the long term. To date, however, there is a dearth of research, particularly with regards to basic metabolomics understanding within Scleractinian corals. Here, the metabolomic profiles (measured using 1H nuclear magnetic resonance (1H NMR) spectroscopy and ultra-high-performance liquid chromatography-mass spectrometry (LC-MS)), of two dominant reef building corals, <i>Acropora hyacinthus</i> and <i>A. millepora,</i> from two distinct geographical locations (Australia, Great Barrier Reef and Singapore), were assessed. We explored how an acute temperature stress shifted the corals baseline metabolomic profile (an increase of 3.25^◦C ± 0.28 from ambient, control levels over 28 days). Regardless of profiling method utilised, metabolomic signatures of coral colonies were significantly distinct between coral species, a result supporting previous work undertaken. Interestingly, this strong species-specific metabolomic signature appeared to mask any differences resulting from the heat stress. This indicates that metabolomics may not be the most sensitive tool for use in studies assessing heat stress and/or adult colonies are not plastic in their metabolomic response to short stress events. That said, it is likely not that simple and further research is urgently needed in order to decouple the cause of this masked metabolomic signature with regard to a corals response to a changing climate.