SEASONAL RECRUITMENT, HABITAT ASSOCIATIONS AND SURVIVAL OF POMACENTRID REEF FISH IN THE UNITED-STATES-VIRGIN-ISLANDS

Patterns of distribution and abundance of coral reef fish depend in pa rt on recruitment of a pelagic larval stage, on subsequent dispersal a mong habitats, and survival of new recruits. We studied recruitment of five species of Stegastes and two species of Chromis damselfish onto reef habitats of St. Thomas, USVI during one year. The two study sites , Flat Cay and Outer Brass Island, were on the southern and northern s ides of St. Thomas, respectively. At both sites, recruitment occurred largely in the summer months, although one species (Stegastes planifro ns) showed significant winter recruitment at Flat Cay. The onset of in creased summer recruitment in 1992 of other species occurred several w eeks later and was shorter in duration at Outer Brass Island than at F lat Cay, perhaps indicating differences in oceanographic conditions (c urrents etc.) or spawning cycles between sites. The two Chromis specie s showed lunar periodicity of settlement at Flat Cay. At Flat Cay, rec ruits of three species (S. leucostictus, S. diencaeus and S. planifron s) were associated with conspecifics possibly due to preferential sett lement. Similarly, new recruits were more often found near live coral than coral rubble, and very few occurred on sand habitat. Substratum c omplexity was a poor predictor of recruitment within a habitat, althou gh larger juveniles of some species were more common on more complex s ubstrate. Contrary to other studies, there were no apparent depth pref erences among recruits, although larger juveniles of two Stegastes spe cies were found more often in deeper water. It appears that within hab itats, newly arriving larvae may be attracted first to the presence of conspecifics and secondarily take up position adjacent to live coral. Apparent survivorship of some Stegastes species and one Chromis speci es was higher at Outer Brass Island than at Flat Cay, and may partly c ompensate for lower recruitment of some species at Outer Brass Island.