Metabolomic richness and fingerprints of deep-sea coral species and populations

Abstract

Introduction: From shallow water to the deep sea, corals form the basis of diverse communities with significant ecological and economic value. These communities face many anthropogenic stressors including energy and mineral extraction activities, ocean acidification and rising sea temperatures. Corals and their symbionts produce a diverse assemblage of compounds that may help provide resilience to some of these stressors.

Objectives: We aim to characterize the metabolomic diversity of deep-sea corals in an ecological context by investigating patterns across space and phylogeny.

Methods: We applied untargeted Liquid Chromatography-Mass Spectrometry to examine the metabolomic diversity of the deep-sea coral, Callogorgia delta, across three sites in the Northern Gulf of Mexico as well as three other deep-sea corals, Stichopathes sp., Leiopathes glaberrima, and Lophelia pertusa, and a shallow-water species, Acropora palmata.

Results: Different coral species exhibited distinct metabolomic fingerprints and differences in metabolomic richness including core ions unique to each species. C. delta was generally least diverse while Lophelia pertusa was most diverse. C. delta from different sites had different metabolomic fingerprints and metabolomic richness at individual and population levels, although no sites exhibited unique core ions. Two core ions unique to C. delta were putatively identified as diterpenes and thus may possess a biologically important function.

Conclusion: Deep-sea coral species have distinct metabolomic fingerprints and exhibit high metabolomic diversity at multiple scales which may contribute to their capabilities to respond to both natural and anthropogenic stressors, including climate change.

Keywords: Callogorgia delta; Chemotaxonomy; Diversity; Rarefaction.

Fig. 1

Rarefaction of Callogorgia delta ions and differences by site. a Rarefaction curves of the union (black), unique union (gray), core (black dashed), and unique core (gray dashed) ions of all C. delta colonies. Points show values rarefied to three C. delta colonies for comparison to other species. b Histogram of the frequency of the detection of each ion in 25 colonies of C. delta. c Rarefaction curves of the union (solid) and core (dashed) ions of C. delta from sites MC885 (blue), MC751 (green), and GC234 (red) and all C. delta (black). d PCA of metabolomes of C. delta colonies from different sites using log₁₀ and Pareto-scaled normalized intensities. Two technical replicates for each colony are plotted. e Number of ions detected per colony and (f) Shannon indices of C. delta from MC885 (blue), MC751 (green), and GC234 (red). Boxes represent first to last quartile while whiskers represent maximum and minimum values excluding outliers. (Color figure online)

Fig. 2

Metabolomic profiles and diversity of five coral species. a Principal component analysis (PCA) of log₁₀ and Pareto-scaled normalized ion intensities for Callogorgia delta (CD, purple circles), Stichopathes sp. (SS, green triangles), Leiopathes glaberrima (LG, red diamonds), Lophelia pertusa (LP, blue squares), and Acropora palmata (AP, yellow inverted triangles). Two technical replicates of each colony are plotted. b Hierarchical clustering analysis of normalized intensities using combined replicates. * denotes clusters with bootstrap values of 100 after 1000 iterations. c Ions detected per colony and d Shannon indices for each species. Boxes represent first to last quartile while whiskers represent maximum and minimum values excluding outliers. e, f Fragmentation spectra of two core ions unique to C. delta samples which match diterpenes such as 8,15-pimaradiene and neocembrene from METLIN. (Color figure online)