Spatial ecology of the steephead parrotfish (Chlorurus microrhinos): an evaluation using acoustic telemetry

Herbivory and other ecosystem processes are widely accepted as important factors in maintaining coral reef resilience. While the spatial scales over which these processes occur have been evaluated, the spatial ecology of individual taxa responsible for shaping these processes is almost entirely unknown. This study combined acoustic telemetry and ecological assessments to evaluate the movement patterns and feeding range of a functionally important coral reef fish, Chlorurus microrhinos (f. Labridae). The diurnal home range and feeding areas of C. microrhinos, on Orpheus Island, Great Barrier Reef, were quantified using active acoustic telemetry. The average diurnal home range of C. microrhinos was 7,830 m(2) +/- 940 (SE). Core areas of activity (50% kernel utilization distributions) were relatively small, encompassing approximately 22% of an individual's home range (1,690 m(2) +/- 220). Core areas exhibited greater topographic complexity. C. microrhinos may select these areas because of decreased predation risk. Feeding intensities were not homogenous throughout the home range. Core areas were found to have a greater number of feeding scars and are thus exposed to increased bioerosion and algal removal by C. microrhinos. While important in shaping key ecosystem processes, the ecosystem impact of individual C. microrhinos in Pioneer Bay appears to be restricted to small areas within a narrow band along the reef crest.