Selective Effects of Environmental Conditions and Protection Levels on Herbivorous Fish Functions in the Largest South Atlantic Reef Complex

ABSTRACT Herbivorous fish are key components in maintaining functionality in reef environments; however, this group is widely threatened by overfishing and habitat degradation. Investigating the main factors determining the structure of herbivorous fish becomes paramount to defining management strategies amid anthropogenic impacts. This study evaluated the drivers of herbivorous fish functional groups (FG) subjected to different environmental conditions and levels of protection in the Abrolhos Bank, Brazil. Sites inside the no‐take area (farther from the shore and characterized by higher coralline algae cover) sustained higher biomass and larger individuals, especially for the excavator (EXCV) parrotfish Scarus trispinosus . Conversely, unprotected, inshore reefs with greater proportions of macroalgae and zoanthids showed lower abundance, biomass and smaller individuals. These results may be attributed to the combined effects of protection and environmental conditions; still, the no‐take area was the most important factor explaining the biomass of all FG. Protection, however, does not influence all FG equally: the biomass of EXCV was about 30‐fold higher inside the no‐take area, while for the other groups, biomasses were about two‐fold higher. The results highlight that different FG require specific management strategies but demonstrate the importance of no‐take areas for herbivorous fish conservation in Brazil.