Live coral predation by parrotfishes (Perciformes: Scaridae) in the Abrolhos Bank, eastern Brazil, with comments on the classification of species into functional groups

Abstract

Parrotfishes (Perciformes: Scaridae) represent a critical functional group on coral reefs because their intense herbivory activity helps in avoiding coral overgrowth by algae. Although feeding preferentially on algae and detritus, some parrotfish species also consume live corals, leading to detrimental effects that may offset the benefits of removing competitive seaweeds. Parrotfish species differ markedly in terms of jaw morphology, foraging activity and extent of substratum excavation, and are typically divided into three functional groups: browsers, scrapers and excavators. The recognition of species within each functional group helps to understand their relative effects in terms of bioerosion, coral fitness and survival, habitat alteration and ecosystem dynamics. Here we report on live coral predation by the Brazilian endemic parrotfishes Scarus trispinosus and Sparisoma amplum in the largest coral reefs of the South Atlantic (Abrolhos Bank, eastern Brazil) and comment on their classification into functional groups based on direct behavioral observations. Scarus trispinosus and Sp. amplum allocated 0.8% and 8.1% of their bites to live corals respectively. Sparisoma amplum fed at lower rates, took shorter feeding forays and larger bites than Sc. trispinosus. Bite rates and foray size were negatively correlated to body size for Sc. trispinosus, but not for Sp. amplum. Our results indicate that Sp. amplum may be primarily recognized as an excavating species, as well as the most specialized parrotfish coral predator in Brazil, while Sc. trispinosus may be recognized as a scraper or excavator depending on its body size. This functional classification corresponds to the classification used for the putative sister taxa of Sc. trispinosus (Sc. coeruleus) and the sister taxa of Sp. amplum (Sp. viride) in the Caribbean, indicating that these two congeneric species pairs play similar ecological roles in different geographic regions.Os budiões (Perciformes: Scaridae) representam um grupo funcional crítico em recifes de corais uma vez que a intensa atividade de herbivoria que desempenham ajuda a evitar a exclusão de corais por algas. Apesar de alimentarem-se preferencialmente de algas e detrito, algumas espécies de budiões também consomem corais vivos, causando efeitos negativos aos corais, os quais podem superar os benefícios decorrentes da remoção de algas. As espécies de budiões diferem acentuadamente em sua morfologia bucal, atividade de forrageio e potencial de escavação do substrato, sendo tipicamente divididas em três grupos funcionais: podadores, raspadores e escavadores. O reconhecimento das espécies nesses grupos funcionais ajuda a entender seus efeitos relativos em termos de bioerosão, condição e sobrevivência de corais, alteração do hábitat e dinâmica do ecossistema. No presente estudo nós registramos a predação de corais vivos pelos budiões endêmicos do Brasil Scarus trispinosus e Sparisoma amplum no maior complexo coralíneo do Atlântico Sul (Banco dos Abrolhos, leste do Brasil) e comentamos sobre a classifi...

Turtle cleaners: reef fishes foraging on epibionts of sea turtles in the tropical Southwestern Atlantic, with a summary of this association type

“…The single previous record (a brief mention) of a parrotfish grazing on turtles' epibionts is an unidentified species of Scarus (Losey et al, 1994). Juvenile parrotfishes act as scrapers, whereas adults may act as scrapers or excavators (Bellwood & Choat, 1990;Francini-Filho et al, 2008). Thus, the species notwithstanding, we suggest that among Scarini those that forage by scraping are the most likely to be recorded foraging on epibionts of sea turtles, as the substrate is adequate for this feeding mode.…”

Relative impact of parrotfish grazing scars on massive Porites corals at Lizard Island, Great Barrier Reef

“…Several individual parrotfish species and groups have been associated with crucial functional roles in reef systems, such as the control of algal communities (Paddack et al 2006, Fox & Bellwood 2007, Bonaldo & Bellwood 2008, 2009, Burkepile & Hay 2008, reef bioerosion (Bellwood et al 2003, Alwany et al 2009, Ong & Holland 2010 and coral predation (Bruckner et al 2000, Francini-Filho et al 2008, Bonaldo & Bellwood 2011). The present study complements this list by providing evidence to suggest that parrotfishes with different feeding modes may have important but significantly different impacts on coral colonies, especially massive Porites spp.…”

“…In addition to the general importance of the parrotfish clade on tropical reefs, a number of studies have highlighted the impact of individual parrotfish groups, species and even individual size classes in shaping the nature and intensity of their ecosystem roles (e.g. Bruckner & Bruckner 1998, Bellwood et al 2003, Bonaldo & Bellwood 2008, 2009, Francini Filho et al 2008, Alwany et al 2009). …”

“…Bellwood & Choat 1990, Fox & Bellwood 2007, Francini-Filho et al 2008, Alwany et al 2009, Bonaldo & Bellwood 2009). In general, parrotfish species on coral reefs may be classified into 2 main functional groups: scrapers and excavators (sensu Bellwood & Choat 1990).…”

An experimental evaluation of macroalgal consumption and selectivity by nominally herbivorous fishes on subtropical rocky reefs

“…Since parrotfishes rely basically on grinding by the pharyngeal teeth to break down the ingested material (Bonaldo et al, 2014), inorganic material may increase the efficiency of this mechanical mastication. This observation is further supported by the fact that a number of parrotfish species feed on live coral colonies, ingesting great loads of their carbonate skeleton (Francini-Filho et al, 2008;Bonaldo and Bellwood, 2011). Similarly, both Acanthurus species observed feeding on the assays possess a thick walled gizzard-like piloric stomach, in which mechanical abrasion occurs.…”