Testing the generality of acoustic cue use at settlement in larval coral reef fish

Abstract

Some settlement-stage larval fish appear to be attracted to reef sound and may, therefore, use acoustic cues when orientating towards their settlement site. However, all work on the in situ response of coral reef fish larvae to sound in acoustic playback experiments has been carried out in the same location (Lizard Island, the Great Barrier Reef), and in some cases, using the same reef recording. It is therefore not clear how widespread acoustic cue use is. To test whether sound is a general and reliable indicator of reef settlement site, we conducted a similar experiment in a different coral reef region, where the coral reef habitat and therefore soundscape is less uniform in quality (Bohol, Philippines). Contrary to our predictions, in some cases we found that fish were not attracted to the broadcast reef sound. We suggest that this may be due to an artefact of the reef recording, possibly the location or the time of day the recording was made. Our results indicate that larval fish are more selective in their response to coral reef sound rather than just being innately attracted to generic reef sound. This highlights the need to assess anthropogenic impacts on the natural soundscape, as this could affect the ability of larval coral reef fish to acoustically detect a suitable settlement site.