Examining the sublethal impacts of environmentally relevant concentrations of Karenia brevis on three South Florida reef-building coral species using a multi-omics workflow

Drastic declines observed in coral reefs in response to changes in climate and other anthropogenic stressors have hinged the survival of these ecosystems largely on the overall health and reproductive success of stony corals. One specific threat, Karenia brevis blooms, has drawn increased public attention in recent decades and has been documented to reach the Florida Keys, a vulnerable coral ecosystem. The purpose of this study was to investigate the sublethal impact of K. brevis exposure on three South Florida “restoration” coral species. Fragments of Porites astreoides, Acropora cervicornis, and Siderastrea radians were exposed to three environmentally relevant concentrations of K. brevis for 2 weeks in a controlled aquaria setting. At the end of exposure, ultra-high-performance liquid chromatography coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) was used to perform nontargeted lipidomics and metabolomics analyses to assess physiological changes in the corals in response to red tide exposure, as well as highlight possible biological processes and pathways altered. Significant changes to the lipidome and metabolome were observed in all three species following exposure. Furthermore, the multi-omics analysis highlighted important pathways for further study including impacts on oxidative stress, energy metabolism, the immune system, and nitrogen fixation/photosynthesis of symbionts. Due to the use of environmentally relevant exposure levels and duration, these results are invaluable to understand possible future impacts of red tide on coral reef areas as well as to inform future coral reef restoration and management decisions.