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We examined whether we could identify the feeding behaviours of the trophic generalist fish Epinephelus ongus on different prey types (crabs and fish) using a data logger that incorporated a three-axis gyroscope and a three-axis accelerometer. Feeding behaviours and other burst behaviours, including escape responses, intraspecific interactions and routine movements, were recorded from six E. ongus individuals using data loggers sampling at 200 Hz, and were validated by simultaneously recorded video images. For each data-logger record, we extracted 5 s of data when any of the three-axis accelerations exceeded absolute 2.0 g, to capture all feeding behaviours and other burst behaviours. Each feeding behaviour was then identified using a combination of parameters that were derived from the extracted data. Using decision trees with the parameters, high true identification rates (87.5% for both feeding behaviours) with low false identification rates (5% for crab-eating and 6.3% for fisheating) were achieved for both feeding behaviours.

SynopsisWe determined the species-specific habitat associations of coral reef fishes and environmental characteristics in an Okinawan coral reef in Japan. We focused on three families (Pomacentridae, Gobiidae and Labridae) and attempted to determine differences in habitat utilization. We selected six sites along the coast of Amitori Bay, from the entrance to the innermost part, in order to cover a wide range of habitat characteristics (exposed habitat, semi-exposed habitat and sheltered habitat). The species diversity of coral assemblages was greater at the exposed and semi-exposed habitats, whereas branching coral mostly covered the sheltered habitat. The environmental factors that determine the species-specific spatial association in fishes differed among families. Both biological characteristics (coral morphology and coral species diversity) and physical characteristics (water depth and wave exposure) affected the spatial association of pomacentrids and gobiids. In contrast, physical characteristics such as substrate complexity and water depth affected the species-specific spatial association of labrid species. Further study is needed to determine the ecological factors that regulate the species-specific habitat preference in Okinawan coral reefs.

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