Source data and code for: Climate change transforms the functional identity of Mediterranean coralligenous assemblages

We used five long-term (>10 years) records of Mediterranean coralligenous assemblages in a multi-taxa, trait-based analysis to investigate MHW-driven changes in functional structure. We show that, despite stability in functional richness (i.e., the range of species functional traits), MHW-impacted assemblages experienced long-term directional changes in functional identity (i.e., their dominant trait values). Declining traits included large sizes, long lifespans, arborescent morphologies, filter feeding strategies or calcified skeletons. These traits, which were mostly supported by few sensitive and irreplaceable species from a single functional group (habitat-forming octocorals), disproportionally influence certain ecosystem functions (e.g., 3D-habitat provision). Hence, MHWs are leading to assemblages that are deficient in key functional traits, with likely consequences for the ecosystem functioning.