Decapod Biodiversity Hotspots and Environmental Drivers: A Macroecological Approach About Bycatch Species in Brazil

ABSTRACT Aim To investigate the spatial patterns of species richness (SR), phylogenetic diversity (PD) and phylogenetic endemism (PE) in bycatch decapod crustaceans along the Brazilian Exclusive Economic Zone and to assess the influence of environmental variables and trawling effort on these diversity indices. Location Brazilian Exclusive Economic Zone. Taxa Decapoda. Methods We compiled bycatch occurrence data from peer‐reviewed studies and global biodiversity repositories. Diversity indices (SR, PD, PE, ED and WE) were estimated using a phylogenetic approach incorporating mitogenomic markers. Environmental and trawling effort data were extracted from global databases, and statistical analyses, including redundancy analysis (RDA), spatial regression and random forest models, were applied to determine the drivers of diversity. Results Decapod diversity showed strong spatial heterogeneity across the EEZ. SR peaked in southeastern Brazil in upwelling‐influenced ecotones, while PD and PE were highest in offshore and equatorial regions. PD was strongly associated with bottom temperature, primary productivity (PP) and current velocity; SR was mainly driven by salinity, light availability and PP; and PE was best explained by temperature and PP. Most hotspots of phylogenetic diversity and endemism fell outside Marine Protected Areas (MPAs), revealing significant conservation gaps in offshore and southern regions. Main Conclusions This study provides the first macroecological framework of decapod diversity in the Brazilian EEZ and one of the first applications of phylogenetic diversity (PD) and phylogenetic endemism (PE) metrics for decapods in the South Atlantic. We show that temperature, salinity, productivity and current dynamics differentially shape biodiversity metrics. Southeastern and offshore zones host unique evolutionary lineages but remain underrepresented in current MPA networks. By integrating phylogenetic and environmental data, our findings offer a baseline to improve spatial biodiversity assessments and support more representative conservation planning under shifting ocean conditions.