Colonisation of artificial mangroves by reef fishes in a marine seascape

Mangroves have been shown to host a variety of fish species that originate from coral reefs. In this study we compare the colonisation of experimental mangrove units, placed on a shallow coral reef and in an adjacent embayment, with species that are commonly observed and believed to rely on the presence of bays containing natural mangroves and seagrass beds (i.e., nursery species) and by other species. After 28 days, density and consequent colonisation rates of both species groups showed a negative trend with increasing distance from the coral reef into the bay, although no significant differences were found among sites. Colonisation rates did not differ between nursery species and other species at any site. Despite the similarity in colonisation rate between the two functional groups, nursery species accounted for over half of the total fish density at each site. These results suggest that nursery species likely dominate the fish assemblage within bay mangroves simply because they occur more abundantly at inland locations than other species, and not because nursery species possess a greater competitive advantage for mangroves compared to other species.