Differential effect of early post-settlement processes on the abundance of two concurrently settling coral reef fishes

Studies of early post-settlement processes in coral reef fishes have focused on small, sedentary species and have neglected the larger, more mobile, fished species. However, because recently settled fishes of both types are small and sedentary, early post-settlement processes might be similar. Here, we compare early post-settlement population dynamics of two naturally co-occurring taxa, Sparisoma (Scaridae), a poorly-studied medium-sized taxon important to artisanal fishers, and Stegastes partitus (Pomacentridae), a well-studied model species. We concurrently monitored density on three reefs in Barbados (West Indies) for 3-3.5 months following a period of high recruitment. Recruitment was >11x (Sparisoma) and >3x (S. partitus) greater than the initial number of large juveniles/adults. Recruit losses were very high (Sparisoma 97%; S. partitus 91%) for both taxa. However, the effect of recruitment on local population size differed qualitatively. After 3-3.5 months, Sparisoma recruitment had no effect on local juvenile density at any site, whereas S. partitus recruitment increased local density (by ~37%) at all sites. Our study does not support the applicability of small, model species to larger, fished ones, highlighting the need for more comparative studies.