Flexibility in size and age at settlement of coral reef fish: spatial and temporal variations in Wallis Islands (South Central Pacific)

Abstract

Competent larvae of 4 tropical reef fish species, i.e. two pelagic spawners (Parupeneus barberinus and Acanthurus triostegus ) and two benthic spawners (Abudefduf sexfasciatus and Dascyllus aruanus ) were collected over two years in Wallis Islands, in order to compare 1) their size and age at settlement, 2) the variability of these parameters and 3) their spatial and temporal variations. The larvae were collected in three sites approximately 10 km apart in September 2002, December 2002, March 2003 and June 2003. The otoliths were examined to obtain early life history information: pelagic larval duration and timing of settlement. Size at settlement varied from 3 mm for A. sexfasciatus , D. aruanus and A. triostegus to 10 mm for P. barberinus . For the benthic spawners, settlement occurred after 17 and 19 days within a narrow age interval (7 to 9 days) and mainly in the middle of the interval. For the pelagic spawners, settlement occurred later (after 35 and 42 days), within a larger age interval (13 days). These estimates are lower than those from other locations in the Pacific but their range is larger. Size at settlement differed significantly between sampling sites only for D. aruanus and between surveys only for A. sexfasciatus . Age at settlement differed significantly between sampling sites only for A. sexfasciatus and between surveys only for D. aruanus . For the pelagic spawners the variability of size and age within site and survey was up to ten times greater than for the benthic spawners. This flexibility would be an advantage for larvae of the pelagic spawners that have to travel greater distances to settle.