Impact of climate change driven freshening, warming, and ocean acidification on the cellular metabolism of Atlantic Cod (Gadus morhua)

Climate change is causing increasing sea surface temperature, ocean acidification and, in near shore waters, freshening. We investigated the metabolic effects of all three and their combination in Atlantic cod from the Skagerrak (eastern North Sea) by measuring concentration changes of a wide range of metabolites involved in energy production in the liver and muscles. Liver metabolism was more strongly affected than muscle, reflecting its central regulatory role. Most amino acid concentrations declined in both tissues across all treatments, and metabolomic pathway analysis revealed significant enrichment in ten metabolic pathways. This suggests enhanced amino acid metabolism in a climate change future. Warming and ocean acidification induced increased liver concentrations of lactate, glucose and fructose 1,6-bisphosphate indicating that gluconeogenesis will increase to meet increased production of enzymes to counter future stress. The molar contribution of glutamine to the total change in liver amino acids constituted 49%, 16% and 29% under warming, ocean acidification and their combination accentuating its importance in energy production also under future climate change. We observed contrasting responses in AMP, ADP, and NAD⁺ concentrations between warming and acidification suggesting possible antagonistic effects. Our findings demonstrate significant and complex metabolic responses to future climate stress in Atlantic cod in northern European waters.