RECRUITMENT AND POST-RECRUIT IMMIGRATION AFFECT THE LOCAL-POPULATION SIZE OF CORAL-REEF FISHES

This study quantifies the contributions of larval recruitment and post -recruit (juvenile and adult) immigration to net increases in populati on size for 150 species of fishes found on ten isolated coral patches or 'bommies' (108-267 m(2)) within a typical reef of the Great Barrier Reef system. At least one third of the total number of recruits and i mmigrants to all bommies were post-recruit fishes, and movement betwee n bommies in 136 species was detected at some time during the 22 month sampling period. The relative numbers of recruits and post-recruit im migrants per species varied widely within the assemblage, and between the replicate bommies. Populations of 95 species received both types o f immigrants, 41 species had only post-recruit immigrants, and 14 spec ies received only larval recruitment. In most species, recruitment occ urred over the austral summer between October and February, while post -recruit movements occurred in both summer and winter. Rates of post-r ecruit immigration varied temporally within bommies, and pulses of pos t-recruits were less temporally concordant between bommies than pulses of recruits. This study is further evidence that post-settlement proc esses can have a significant effect on the local population size of re ef fishes.