Mesophotic zone as refuge: acclimation and in-depth proteomic response of yellow gorgonians in the Mediterranean sea

The intensification of warming-induced mass-mortalities in invertebrate populations including in temperate regions is a critical global issue. Mesophotic zones (30–150 m depth) have been suggested as potential refuges from climate change for gorgonian populations, offering hope for reseeding damaged shallow populations. Using a proteomic approach, we investigated the responses and acclimatization ability of the yellow gorgonian Eunicella cavolini along an environmental gradient following reciprocal transplantations between shallow (20 m) and mesophotic (70 m) zones. Our findings indicate that yellow gorgonians from mesophotic waters exhibit a greater plasticity when transplanted to shallow waters, compared to shallow gorgonians transplanted to the mesophotic zone at 70 m. Transplanted colonies from mesophotic to shallow waters showed an increasing level of proteins involved in immune response but displayed no signs of necrosis or apoptosis, highlighting the acclimation potential of mesophotic populations. These results suggest that Eunicella cavolini populations may exhibit physiological plasticity in response to future climate change, allowing natural colonization from mesophotic populations. This analysis offers valuable insights into gorgonians' cellular and molecular responses to environmental changes.