Territoriality and habitat use by juvenile blue tangs, Acanthurus coeruleus

We studied territoriality and habitat use by yellow phase juvenile blue tan gs, Acanthurus coeruleus, on a small fringing reef in Barbados, West Indies . Juvenile blue tangs occurred on the reef crest, spurs, and a transition z one between the reef crest and reef flat at a density of about 8 individual s per 100 m(2), but were much rarer on the reef flat. They were solitary an d occupied stable home ranges (median=0.85 m(2)) that increased with body s ize. Observational and experimental data documented aggressive defense of h ome ranges against conspecific and to a lesser extent congeneric, A. bahian us, juveniles (about 7.5 approaches and attacks per hour directed at intrud ers). Home range locations were structurally more complex and closer to a v ertical face than expected by chance. Although juvenile blue tang territori es overlapped considerably with those of larger and more aggressive Stegast es damselfish, which are believed to exclude solitary adult Acanthurus spp. from reef crest and spurs, the tangs avoided Stegastes and were rarely cha sed (< 0.3 fleeing events per hour). Space use and social organization of y ellow juvenile blue tangs contrast strikingly with that of both conspecific adults and congeneric juveniles.