Patterns and trends in coral reef macroalgae browsing: a review of browsing herbivorous fishes of the Indo-Pacific

Browsing fishes have been identified as an important component of coral reef resilience, because in contrast to other herbivorous fishes they are able to feed on established macroalgae. Climate change and local anthropogenic impacts have contributed to phase shifts in many coral reefs from coral to macroalgae dominance, and recent research suggests the potential ability of browsers to reverse such phase shifts. However, there is high variation among studies and some contradicting findings exist. Here, we review the relevant literature to assemble a list of species currently known to contribute to browsing in the Indo-Pacific. Furthermore, we identify spatial and temporal patterns, outline factors influencing browsing, and discuss the probability of phase shift reversal. We formulate research recommendations addressing the identified gaps in knowledge about the interactions of browsing fishes and their environment. To date, 37 species of fishes have been observed consuming macroalgae in the Indo-Pacific. The most important groups are the family Siganidae, the subfamily Scarinae (Labridae), and the subfamily Nasinae (Acanthuridae). Browsing species vary between studies depending on location, season and macroalgae species examined. Several influencing factors, such as structural complexity, palatability of macroalgae and ecosystem connectivity have been suggested to cause these discrepancies. The most promising avenues for future research are the effect of structural complexity, the importance of mobile link species and influences of food availability on the selectivity of browsing species. Increasing our knowledge in these fields will provide a better basis for successful management strategies directed at increasing the resilience of coral reefs.