Diversity, distribution and environmental drivers of coralline red algae – the major reef builders in the Southwestern Atlantic

Diversity, distribution and environmental drivers of coralline red algae – the major reef builders in the Southwestern Atlantic Coralline red algae (CRA) are key players in the construction, maintenance and quality of biogenic reefs in the Southwestern Atlantic (SWA). CRA are currently affected by global and local stressors, and little is known about their biodiversity and the environmental drivers that influence their distribution patterns in the SWA. In the present study, we quantified the species richness of CRA in the region based on DNA-based species delimitation methods, verified their distribution and identified the main drivers shaping the macroecological patterns of richness and β-diversity. We found 79 phylogenetic species in the tropical and warm temperate SWA, and temperature, nutrients and water current velocity were the most relevant acting as environmental filters selecting particular flora for most of the evaluated ecoregions. The Eastern Brazil ecoregion stands out due to its richness, β-diversity and as a transitional zone. The findings of our study have several important practical implications subsidizing actions for monitoring and conservation plans of coastal oceanic and mesophotic zone.