The present study explored the importance of chemical cues for habitat selection by fish (6 species), crustacean (1 species), and cephalopod (1 species) larvae in a 4-channel choice flume at Ishigaki Island, Japan. The larval attraction toward chemical cues from reef patches (seagrass bed patch, live coral patch, dead coral patch, and control water; Expt 1) and microhabitats within a given reef patch (live coral colonies, dead coral colonies, seagrass, and conspecifics; Expt 2) was tested in a 4-channel choice flume. The results in Expt 1 showed that 3 fish species used chemical cues to move significantly towards reef patches: Chromis viridis toward live coral patch water and Lutjanus fulviflamma and L. gibbus toward seagrass bed patch water. In Expt 2, 6 of 8 species (4 fishes, 1 cephalopod, and 1 crustacean) used chemical cues to move significantly toward conspecific water (Apogon properuptus, C. viridis, Dascyllus reticulatus, L. fulviflamma, Octopus cyanea, and Palaemonidae sp.). Overall, these results suggest that marine species can actively select settlement habitats according to olfactory cues (more specially, cues from conspecifics). Moreover, these results highlight the importance of conspecific cues over other types of information (reef patch and microhabitat) for habitat selection. Social aggregation of fish, crustacean, and cephalopod larvae with older conspecifics may be the result of individuals using conspecific 'guides' to potentially find beneficial resources (availability of resources and low mortality).
KEY WORDS: Sensory mechanisms · Settlement cues · Fish · Crustacean · CephalopodResale or republication not permitted without written consent of the publisher Aquat Biol 19: 231-238, 2013 patch (e.g. Montgomery et al. 2006, Huijbers et al. 2008, Lecchini et al. 2013), a suitable recruitment microhabitat (e.g. Munday et al. 2009, Igulu et al. 2011, Devine et al. 2012), predators (Dixson et al. 2012, or conspecifics (e.g. Lecchini et al. 2010, Lecchini 2011.For example 1 (island or continental shelf detection), Leis & Carson-Ewart (2003) have shown that fish larvae orientate themselves toward or away from an island when they are at least 1000 m away. For 2 (reef patch detection), Huijbers et al. (2008) reported that settling fish larvae are capable of olfactory discrimination and prefer the odor of their home reef (mangroves and seagrass beds versus coral reefs). For 3 (microhabitat or conspecific detection), Lecchini et al. (2010) showed that crustacean larvae made active habitat choices among the microhabitats tested (live coral, dead coral, macroalgae, and sand), and these species distinguished between their preferred microhabitat versus another habitat and be tween conspe cifics and heterospecifics, using visual and/or olfactory cues.Despite these recent studies on sensory cues used by marine larvae to select a habitat, the sensory and behavioral mechanisms by which larvae disperse and return from their oceanic phase to adult reef habitats are still not known, particularly for c...