Metabolic responses to elevated pCO2 in the gills of the Pacific oyster (Crassostrea gigas) using a GC-TOF-MS-based metabolomics approach

Abstract Rising atmospheric carbon dioxide (CO 2 ), primarily from anthropogenic emissions, are resulting in increasing absorption of CO 2 by the oceans, leading to a decline in oceanic pH in a process known as ocean acidification (OA). There is a growing body of evidence demonstrating the potential effect of OA on the energetics/physiology and consequently life-history traits of commensally important marine organisms. However, despite this little is known of how fundamental metabolic pathways that underpin changes in organismal physiology are affected by OA. Consequently, a gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) based metabolic profiling approach was applied to examine the metabolic responses of Crassostrea gigas to elevated p CO 2 levels, under otherwise natural field conditions. Oysters were exposed natural environmental p CO 2 (~625.40 μatm) and elevated p CO 2 (~1432.94 μatm) levels for 30 days. Results indicated that 36 differential metabolites were identified. Differential metabolites were mapped in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database to search for the related metabolic pathways. Pathway enrichment analysis indicates that alanine, aspartate and glutamate metabolism and glycine, serine and threonine metabolism were the most statistically enriched pathways. Further analysis suggested that elevated p CO 2 disturb the TCA cycle via succinate accumulation and C. gigas most likely adjust their energy metabolic via alanine and GABA accumulation accordingly to cope with elevated p CO 2 . These findings provide an understanding of the molecular mechanisms involved in modulating C. gigas metabolism under elevated p CO 2 .