Ranking Herbivory in Coral Reef Fish

Herbivory grazing patterns by parrotfish, family Scaridae, and surgeonfish, family Acanthuridae, were investigated on the leeward side of Bonaire, Netherlands Antilles. Due to overfishing, coral disease, declining water quality and global climate changes, coral reefs worldwide are in danger of undergoing phase shifts from coraldominated to algal-dominated ecosystems (Hughes 2007; Nybakken 2001). When nutrient levels are high, algal communities are highly productive and may outcompete corals (Breeman et al 1994). In healthy coral systems herbivores suppress algal growth and are a key component in preventing phase shifts, thus managing reef resilience (Hughes 2007; Folk and Nystrom 2001). This study measured herbivory rates and bite sizes of several species of coral reef fishes on the island of Bonaire, Netherlands Antilles. These measurements and species density data (Steneck 2005) were used to rank species according to their level of herbivory. The five selected herbivore species were the terminal and initial phase Sparisoma viride (Stoplight Parrotfish), terminal and initial phase Scarus vetula (Queen Parrotfish), terminal phase Scarus taeniopterus (Princess Parrotfish), Acanthurus coeruleus (Blue Tang), and Acanthurus bahanus (Ocean Surgeon). Although Scarus vetula has the highest grazing rate (# bites/min) and largest bite size (cm2 ), this study calculates that Scarus taeniopterus, due to large densities, are the primary consumers of algae in the waters of Bonaire (cm2 /minute/species/100m2 ), followed by Scarus vetula terminal phase and Scarus vetula initial phase. As coral reefs are becoming more algal dominated due to nutrient enrichment, knowledge of herbivore ecology and management of herbivore populations is critical to understanding and protecting these threatened ecosystems.

This student research was retrieved from Physis: Journal of Marine Science III (Spring 2008)19: 49-54 from CIEE Bonaire.