MEPS 226:157-164 (2002)  -  doi:10.3354/meps226157

ABSTRACT: While larval supply patterns play a major role in determining the distribution and abundance of reef fishes at a range of spatial and temporal scales, events occurring in the weeks after settlement may also significantly alter the demography of a juvenile population. I monitored over 2 summers the arrival of new recruits of 6 species of benthic damselfish onto continuous and patch reef habitat in One Tree Island lagoon. Each species had specific habitat preferences, and most showed some form of patchiness in spatial and temporal distribution at settlement; however, this was most likely a result of group settlement rather than habitat patchiness. Tagged recruits of Pomacentrus amboinensis remained within 1 m of their settlement site for at least the first 36 d on continuous reef, while known individuals of other species also moved little during this period, suggesting that disappearances were likely to be due to mortality. Mortality of recruits varied among species, years and habitats (patch vs continuous reef), and consequently spatial distributions of fish changed after settlement at the scale of 10s of metres (within-site) and several kilometres (among 8 sites). The spatial patchiness in distributions was not consistent among species, sites or years, suggesting that spatial variation in substrate did not have a major effect on settlement variation at this scale. These results show that the settlement signal may be obscured in the first few weeks post-settlement, and that less-frequent censuses, commonly used as proxies for high-frequency monitoring of settlement, may not accurately hindcast spatial or temporal patterns of settlement.

KEY WORDS: Damselfishes · Group settlement · Migration · One Tree lagoon · Post-settlement mortality