Herbivorous fishes such as parrotfishes (Scaridae) play a crucial role in maintaining reef health by grazing macroalgae that would otherwise out-compete corals for space. Full appreciation of this contribution, however, depends on understanding the spatiotemporal patterns of parrotfish habitat utilization. Studies on spatial dynamics of parrotfish have been limited to short temporal spans (days to weeks) or coarse spatial resolution (kilometers). In this study, we used an underwater acoustic tracking system to monitor the movement and activity of 23 individuals, from three parrotfish species, for up to 520 days. We found that parrotfish exhibited surprisingly high degrees of sleeping and foraging site fidelity, between which they commuted daily. Consequently, diurnal activity was restricted throughout the entire study duration, to the same confined areas (7,155 ± 800 m², mean ± SE). These high activity areas should be compared to the total home range area of 51,990 ± 7,174 m². These results suggest that the ecological impact of individual parrotfish grazing is far more restricted than expected from their overall home range. The extremely constrained foraging areas raise concerns of the capacity of parrotfish to mitigate phase shifts in coral reefs by spatially adjusting their foraging behaviors.  From a broader perspective, this study highlights the importance of looking beyond overall home range, to examine spatiotemporal patterns of specific activities.

Acoustic telemetry