Interspecific differences in foraging behaviour and functional role of Caribbean parrotfish

Abstract

Herbivory is one of the most important biological processes influencing coral reefs. In the highly diverse Indo-Pacific reef fish communities, different herbivores can have strikingly different functions. We investigated the extent of functional diversity among herbivorous parrotfish of the more species-depauperate Caribbean Sea. We carried out observations of seven species of parrotfish (Scarus taeniopterus, Sc. vetula, Sc. iserti, Sparisoma viride, Sp. aurofrenatum, Sp. rubripinne and Sp. chrysopterum) on four Barbadian coral reefs to collect information on foraging techniques, rates, and targets, and found marked interspecific variation. Species of the genus Scarus had higher foraging rates than those of the genus Sparisoma. Different species took varying amounts of live coral, turf algae and macroalgae. A functional categorization based first on foraging technique (contact or no contact with the substratum) and secondarily on the more conventional criterion of foraging target (macroalgae, turf algae and live coral) allowed us to classify Sc. taeniopterus and Sc. iserti as 'scrapers', Sp. aurofrenatum, Sp. rubripinne and Sp. chrysopterum as 'grazers', Sp. viride as a 'bioeroder' and Sc. vetula as a 'bioeroder/scraper'. This functional group affiliation, together with species-specific foraging rates, allows us to predict the role of Caribbean parrotfish on major coral reef processes and their impact on coral reef benthic communities.

Diversity of trophic niches among herbivorous fishes on a Caribbean reef (Guadeloupe, Lesser Antilles), evidenced by stable isotope and gut content analyses

“…Sparisoma aurofrenatum seemed to have a similar diet than Acanthuridae, in terms of proportions of assimilated food items. These results were in accordance with the previous classification of herbivorous fishes into functional groups, since S. aurofrenatum, Acanthurus chirurgus and A. bahianus are defined as "grazers" in the literature (Bellwood and Choat 1990, Cardoso et al 2009, Green and Bellwood 2009). …”

“…The ecology of herbivorous fishes, including feeding preferences, has been studied before in the Caribbean (Bruggemann et al 1994, McAfee and Morgan 1996, Ferreira and Gonçalves 2006, Burkepile and Hay 2008, Cardoso et al 2009). Following these studies, herbivorous fishes have been divided into functional groups: grazers, scrapers, browsers and bioeroders, based on adult morphology and feeding behavior (Bellwood and Choat 1990, Cardoso et al 2009, Green and Bellwood 2009).…”

“…Following these studies, herbivorous fishes have been divided into functional groups: grazers, scrapers, browsers and bioeroders, based on adult morphology and feeding behavior (Bellwood and Choat 1990, Cardoso et al 2009, Green and Bellwood 2009). However, the determination of their trophic niche with precision remains challenging.…”

“…Trophic niches have been described with digestive content analyses (Randall 1967, Tilghman et al 2001, Ferreira and Gonçalves 2006 or direct observations of feeding behavior in the field by the counting of "bites" (Frydl and Stearn 1978, McAfee and Morgan 1996, Burkepile and Hay 2008, Cardoso et al 2009, Kopp et al 2010). However, these methods do not provide an accurate description of the diet and present several practical problems (Bearhop et al 2004).…”

Coral Reef Resilience through Biodiversity

“…Many studies of resilience emphasize the role of herbivory in reef recovery following disturbances. It is becoming clear that different herbivorous �sh species (e.g., Scaridae and Acanthuridae) can vary in their ability to control algal cover and open up new space for coral recruitment [189,190]. We need to know which �sh species are indicators of reef regeneration and which other groups besides herbivores can play a role in making reefs more resilient [65].…”