Meeting Abstract
Coral habitats are highly abundant in the Gulf of Mexico, including mesophotic coral ecosystems between 30–150 m, but there is a lack of understanding regarding the ecological roles of mesophotic corals & the functional differences among depth-generalist conspecifics. We designed an integrative approach examining transcriptomics, morphometrics, & algal endosymbionts to quantify natural variation of shallow & mesophotic Montastraea cavernosa colonies. RNA-Seq profiling was conducted across 4 sites with shallow & mesophotic habitats in the Gulf of Mexico & Caribbean, including Belize, Flower Garden Banks, Pulley Ridge, & Dry Tortugas. Variability across regions was a stronger driver of coral gene expression compared to differences between depth zones within regions. Metabolic gene pathways were consistently under-expressed at depth, while cell division pathways were highly expressed & may reflect increased algal symbiont density in mesophotic corals. Additionally, transplant experiments at the Flower Garden Banks identified plastic gene expression within 6 mo. after relocation across depth zones. During a bleaching event at 12 mo., we observed lower stress resilience in transplants from mesophotic to shallow depths as compared to shallow controls. However, gene expression during bleaching suggested potential metabolic & symbiont recovery in transplants and was corroborated by follow-up observation at 36 mo. This integrative study provides a better understanding how variation in gene expression can contribute to corals’ flexibility in different environments. Knowledge of coral adaptation to light-limited environments can improve predictions regarding the roles mesophotic coral ecosystems may play in survival of shallow coral reefs.
