摘要：Abstract Herbivorous reef fishes are an important component of coral reef ecosystems and a focal point in reef management. Herbivore diets have been examined using a myriad of methods, making it difficult to compare between analyses and to examine consistency or variability in diet across large spatial scales or heterogeneous environments. Here, we present a method to quantify and validate the diet diversity of these important coral reef species. We compile a database of information on Pacific herbivorous reef fishes through a systematic review of published diet data, and for those studies in which appropriate information is reported, we calculate a single Simpson's Diversity Index value to represent the diet diversity of each. We then validate this approach by examining the diet diversity of five species using DNA metabarcoding to sequence the algae present in their stomach contents. The two approaches provided comparable estimates of diet diversity, and we find evidence for considerable diet variability both within functional groups and between closely related species. Although there is a wide range of diet specialization within each functional and taxonomic group, parrotfishes and detritivorous surgeonfishes appear to have more limited diets than other nominal herbivorous fishes in our survey. This may make them more vulnerable to habitat degradation, which is important considering that both groups face considerable fishing pressure in Hawaiʻi and elsewhere in the Pacific. Finally, we demonstrate how this approach to quantifying diet can be incorporated into trait matrices that offer valuable insight into the dissimilarity between species, regardless of their taxonomic and functional classification. This analysis offers a simplified quantitative index of diet diversity that can contribute to better management of herbivores and increased understanding of their functional effects on changing, degraded reefs.
