Comparative analysis of foraging behavior and bite mechanics reveals complex functional diversity among Caribbean parrotfishes

Parrotfishes are a diverse group of herbivores that can influence benthic community dynamics and ecosystem function on coral reefs. Different species and size classes of parrotfishes vary in their feeding ecology and can impact reef ecosystems in distinct ways. We documented differences in the feeding ecology of 9 species of parrotfishes in the Florida Keys National Marine Sanctuary (FKNMS). Many of the key differences can be summarized by assigning species to functional groups (e.g. scrapers, excavators, croppers, macroalgae browsers), which are differentially responsible for carrying out specific ecological processes. For example, we found that Sparisoma viride, Scarus coelestinus, Sc. guacamaia, Sc. taeniopterus, and Sc. vetula feed on short turfs with few sediments, while Sp. aurofrenatum, Sp. chrysopterum, and Sp. rubripinne feed on longer sediment-laden turfs in addition to macroalgae. Further, parrotfishes use distinct bite types that indicate contrasting impacts on the benthos. Species that feed on short turfs scrape and excavate epilithic and endolithic algae, while species that feed on longer turfs and macroalgae tend to tear or crop algae from the reef. These distinct feeding behaviors result in different rates of algae removal, carbonate erosion, and sediment production. Recognizing that different species of parrotfishes interact with the benthos in fundamentally different ways will enable scientists and managers to better predict how changes in the structure of parrotfish assemblages may affect benthic communities and ecosystem processes.