(50) Macroalgae Weeding Behavior of Stegastes Damselfish in Algae Gardens

     Damselfish (family Pomacentridae) are often territorial herbivorous fishes that maintain gardens of palatable turf algae within their territories. Fishes prune their gardens by ‘weeding’ out macroalgae and coral... [ view full abstract ]

     Damselfish (family Pomacentridae) are often territorial herbivorous fishes that maintain gardens of palatable turf algae within their territories. Fishes prune their gardens by ‘weeding’ out macroalgae and coral polyps that would otherwise threaten the health and extent of the garden; however, some species have been shown to allow certain macroalgae to continue growing. This study examines the weeding behavior of damselfish in the genus Stegastes when macroalgae is introduced to their territories. We hypothesized that Stegastes damselfish would exhibit preferential weeding behavior when presented with three species of brown macroalgae. Our methods included introducing pieces of three species of brown macroalgae (Dictyota, Padina, and Sargassum) into Stegastes territories followed by 15-minute behavioral observations of the individuals. Our results show that Stegastes individuals do not exhibit preferential weeding behavior among the three macroalgae species, and our hypothesis was not supported. We observed that the appearance of macroalgae in damselfish territories resulted in increased aggressive behavior toward other fish rather than causing a change in weeding behavior. Understanding the contribution of territorial damselfish to the distribution of coral, macroalgae, and turf algae in the coral reefs is important in the face of global threats to reef health.