Seawater increasing temperature significantly affect marine ecosystems, threatening biodiversity and essential ecosystem functions. Therefore, the identification of thermal preferences of the species is of paramount importance to determine the response of the marine community to climate change.

This work aims to establish a rigorous methodological approach to characterize the thermal preference of the demersal species collected in the North-Western Ionian Sea, identifying the thermal optimum associated with the maximum probability of presence for each taxon.

The core value of this analysis lies in the use of a thirty-year standardized time series data, integrating demersal species distribution with seabed temperature. Specifically, data were gathered annually from 1995 to 2025 within the EU Data Collection Framework, during the MEDITS (Mediterranean International Trawl Survey) experimental bottom trawl surveys, conducted in the North-Western Ionian Sea (Geographical Sub-Area 19), covering a bathymetric range between 10 and 800 meters in depth.

The preferential temperature of over one hundred species of different faunistic categories (Cephalopods, Crustaceans, Cartilaginous and Teleosts fishes) was obtained through the development of Generalized Additive Models (GAMs). Indeed, sea-bottom temperature data, connected to the presence/absence of the demersal species along the historical data series, were projected onto a high-resolution continuous space to estimate the thermal preference values (optima). The application of strict diagnostic protocols ensured the statistical robustness of the applied model.

The availability of thermal optima of the demersal species, can allow future analysis to detect the marine ecosystem responses to local warming and to predict the evolution of the demersal community under the pressure of future climate scenarios.