‘Tropicalization’ of megafauna community in a South Atlantic warming hot spot: evidences from demersal fisheries off Brazil

Abstract The Southwest Atlantic Ocean comprises a major ‘marine warming hotspot’ subject to significant marine ecosystem changes. Among them, a process of ‘tropicalization’ of demersal fauna has been proposed, as determined by the increasing influence of the warm Brazil Current, gradually expanding towards higher latitudes. We identified signals of fauna ‘tropicalization’ analysing commercial catches of 29,021 multispecies demersal fishing operations conducted in the Brazilian Meridional Margin between 2000 and 2019. These signals included changes in species catch composition and patterns of biomass gains and losses of species with affinities for warm- and cold-waters, respectively. In addition, annual variability of the Mean Temperature of the Catches increased sharply from 2013 onwards at a rate of 0.41°C yr− 1, explained by increasing sea bottom temperatures (with 0 and 1-year time-lag) and the transport volumes of the Brazil Current (4-year time-lag).