The influence of habitat characteristics and conspecifics on attraction and survival of coral reef fish juveniles

In marine species with a pelagic larval stage, search behavior and selection of a suitable reef habitat can maximize the settlement success of recently settled juveniles and their subsequent performance (growth and survival of juveniles). Our objective was to test this hypothesis for a single target coral reef fish species (Chromis viridis) at Moorea Island. C. viridis settle on living coral colonies of Porites rus already populated with conspecifics. In the present study (conducted in experimental cages), we found that: 1) mortality rate of recently settled juveniles of C. viridis was lower in the settlement habitat (living coral colonies of P. rus) than in other habitats having physical structure different from those of P. rus colonies; 2) C. viridis juveniles preferentially colonized coral heads of P. rus with conspecifics present rather than uninhabited coral heads and they also preferentially colonized uninhabited coral heads rather than coral heads with heterospecifics; 3) mortality rate of C. viridis juveniles did not vary with the presence or absence of conspecifics or heterospecifics on P. rus colonies. Overall, the study allows us to highlight that site selection by juveniles for habitat containing conspecifics does not benefit their short term mortality rates, suggesting that in the short term at least, site selection has little importance.