Settling larvae of a small coral-reef fish discriminate reef features at large, but not small, spatial scales

Larval settlement of a small coral-reef fish, the bridled goby (Coryphopterus glaucofraenum), to five entire reefs over 4 yr decreased with increasing cover of hard substrate (rock and coral). Experimentally increasing rock cover on these large reefs caused a reduction in settlement that lasted 3 yr, confirming that settling coral-reef fish discriminate among sites at the mesoscale (hundreds of meters to tens of kilometers). Counterintuitively, a small-scale manipulation of rock cover and an observational study both suggest that settlers show no response to rock cover at the microscale (few to tens of meters). Habitat selection at settlement can, thus, set initial benthic population size at much larger spatial scales than previously recognized, a finding consistent with the good swimming and sensory capabilities of late-stage larvae.