Non-additive phospholipidomic responses to ocean warming and acidification drive intraspecific variation in cell membrane vulnerability in a marine ectotherm

The lipidome is fundamental to the good functioning of cells and organisms. However, its role in species acclimatisation and adaptation to global changes remains overlooked. Investigating intraspecific variation in lipidome responses to combined global change drivers is therefore paramount to predict species' vulnerability in future oceans. Here, we profiled the phospholipidome of the Northern shrimp, Pandalus borealis, from four different origins in the Northwest Atlantic, within an orthogonal design of ocean warming (OW) and acidification (OA) scenarios. We report complex origin-dependent non-additive responses under combined global changes. Shrimp display a high degree of intraspecific variation with distinct profiles of synergism, antagonism or temperature-driven phospholipidome responses when OA is superimposed on OW. Shrimp from the southernmost origin are only sensitive to OW, whilst those from the other three origins respond to combined OW and OA. These patterns involve changes in cellular membranes' unsaturation, fluidity, curvature and thickness, underlying differential intraspecific cellular vulnerability to global changes. The isolated effects of OA are subtler, visible only in shrimp from the St. Lawrence Estuary (SLE). Shrimp from SLE also show the most pronounced phospholipidome remodelling, allowing them to acclimate to combined OW and OA. Whilst SLE shrimp seem most sensitive to global changes, those from the northernmost origins (Newfoundland and Esquiman Channel) display the greatest cellular vulnerability under combined OW and OA. Our findings evidence the highly complex interplay of OW and OA in remodelling marine ectotherms' phospholipidomes, with direct implications for prioritising conservation efforts on populations most vulnerable to global changes.