Characterization of benthic and demersal assemblages in a trawling fishing area through the IndVal-based approach

This study presents a preliminary analysis on the characterization of both demersal and benthic macrofaunal assemblages in the north-western Ionian Sea (NWI, Central Mediterranean Sea), focusing on the shelf and slope soft bottoms of the eastern Salento Peninsula. Species specificity and fidelity were assessed through the Indicator Value (IndVal) approach combined with multivariate analyses applied to biomass data acquired from the MEDITS database over three seasonal surveys. Multivariate analyses showed a distinction of three assemblages in the shelf area, while a unique bathyal assemblage was detected. Any significant seasonal difference was tested in the structure of the assemblages. Eurytopic species identified in the analysis (Merluccius merluccius and Parapenaeus longirostris) were coherent with their biological features. A particularly notable result is the identification of purple heart sea urchin (Spatangus purpureus) as the main stenotopic benthic species of the shelf break assemblage, with the highest values of specificity and fidelity to this assemblage.