Parrotfish functional morphology and bioerosion on SW Atlantic reefs

Parrotfishes (Labridae: Scarini) have jaws formed by teeth fused into a beak-like structure in most species, and are classified into 3 functional groups (browsers, scrapers and excavators) based on jaw morphology, foraging behavior and feeding impact on the benthos. We compared the feeding morphology of 3 parrotfish species in the Abrolhos Bank, SW Atlantic. We also estimated rates of bioerosion caused by the largest and most abundant parrotfish in the region, Scarus trispinosus, and compared them to literature estimates from 12 species. The 3 studied species differed in dentary, suspensorium and mouth/head height. Large (>40 cm) Sc. trispinosus individuals were functionally classified as excavators because of their body size, robust premaxilla and jaws with simple joints, in addition to the large proportion of their bites leaving pronounced marks on the substratum. Large (>40 cm) adult Sparisoma amplum were also classified as excavators because of their mouth/head height, dentary and suspensorium size and robust jaws (dentary) with simple joints. Sc. zelindae had the most mobile jaw among the 3 species and was functionally classified as a scraper, as were juveniles or initial phases of the other 2 species. Body size and feeding rates of Sc. trispinosus were positively correlated with the volume of substratum removed, with large adults removing 207 cm3 d-1 and eroding ~75500 cm3 yr-1. Our results reinforce the importance of studies on jaw morphology and osteology for the assessment of parrotfish feeding modes, and indicate that large adult Sc. trispinosus and Sp. amplum play unique roles as excavating fishes in the Abrolhos Bank62914916