Metabolic Profiling Reveals Biochemical Pathways Responsible for Eelgrass Response to Elevated CO₂ and Temperature

As CO₂ levels in Earth's atmosphere and oceans steadily rise, varying organismal responses may produce ecological losers and winners. Increased ocean CO₂ can enhance seagrass productivity and thermal tolerance, providing some compensation for climate warming. However, the metabolic shifts driving the positive response to elevated CO₂ by these important ecosystem engineers remain unknown. We analyzed whole-plant performance and metabolic profiles of two geographically distinct eelgrass (Zostera marina L.) populations in response to CO₂ enrichment. In addition to enhancing overall plant size, growth and survival, CO₂ enrichment increased the abundance of Calvin Cycle and nitrogen assimilation metabolites while suppressing the abundance of stress-related metabolites. Overall metabolome differences between populations suggest that some eelgrass phenotypes may be better suited than others to cope with an increasingly hot and sour sea. Our results suggest that seagrass populations will respond variably, but overall positively, to increasing CO₂ concentrations, generating negative feedbacks to climate change.