Chemical cues from habitats and conspecifics guide sand-smelt Atherina presbyter larvae to reefs

Abstract

Chemical cues have been widely addressed as potential cues for fish larvae to orient, detect or remain close to suitable habitat. However, most studies to date have been on tropical reef species and have suggested a chemosensory-driven homing behaviour, with only few studies on temperate fish indicating a less conclusive response to chemical cues. We hypothesized that detection and response to chemical cues might provide an important mechanism maintaining the larvae of a temperate reef fish species (sand-smelt Atherina presbyter Cuvier, 1829), close to their natal reef. The ability to discriminate chemical cues from different rocky reefs, and natal and non-natal conspecifics was tested. Water and shoals of sand-smelt larvae were collected from 3 reefs, and larval preference was tested in a 2-choice flume chamber. Larvae preferred nearby reefs over natal reefs and discriminated and preferred conspecifics from their natal reef. Moreover, our results suggested that both cues are equally relevant, as the combination of reef cues with conspecifics was more attractive to sand-smelt than either cue in isolation. When conspecific and reef preferences were tested against each other, there was no longer a clear preference for either cue. Additional tests suggested that preference for conspecifics could be driven by either diet or habitat-related chemical cues. Chemical cues and the corresponding detection mechanisms likely play an important role in finding suitable habitat and increasing the fitness of temperate reef fish.