WHEN DO ADULT REEF FISHES DIE?
Mortality is considered to be critically important in shaping reef fish communities, however, we currently know remarkably little about the nature of mortality in adult coral reef fishes. Mortality on coral reefs is intrinsically linked with predation, with most evidence suggesting that key predators are usually on the hunt during dawn and dusk. We tested this 'crepuscular predation' hypothesis using passive acoustic telemetry movement data to determine the time of day of potential mortality events of adult herbivorous reef fishes. Furthermore, we identified five types of potential mortality events based on the nature of change in signal detections from tagged fishes. We found that the majority of the potential mortality events were characterised by an abrupt stop in detections, possibly as a result of a large, mobile predators such as a carangids or reef sharks. Mortality in adult herbivorous reef fishes is higher during the day than previously expected. The time of day of the potential mortality events suggest that predation was highest during the day and crepuscular periods, and lowest at night, offering only partial support for the crepuscular predation hypothesis. Visually-oriented, diurnal and crepuscular predators appear to be more important than their nocturnal counterparts in terms of predation on adult reef fishes. By revealing the timing of potential mortality events, passive acoustic telemetry may offer an important new tool for investigating the nature of predation on coral reefs.
Khan, J. A., James Cook University, Australia, email@example.com
Welsh, J. Q., James Cook University, Australia, firstname.lastname@example.org
Bellwood, D. R., James Cook University, Australia, email@example.com
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