Resource limitation and recruitment patterns in a coral reef fish assemblage

Abstract

The potential effects of food and shelter availability on the recruitment and early survivorship of coral reef fishes were studied on St. Croix, U.S. Virgin Islands. The faunal assemblage studied included diurnally active fishes found in the “rubble/sand” habitat. The most abundant members were: beaugregory, Stegastes leucostictus (Muller & Troschel), goldspotted goby, Gnatholepis thompsoni Jordan, bridled goby, Coryphopterus glaucofraenum Gill, surgeonfishes, Acanthurus bahianus Castelnau and A. chirurgus (Bloch), and French grunt, Haemulon flavolineatum (Desmarest). Comparisons of recruitment to reefs constructed from substrata that varied in morphological characteristics showed that there were differences in the relative abundances of recruits attracted to and/or surviving on the different reef types. Juveniles of most species appeared to prefer the branching coral Porites porites (Pallas), which provided a large number of small crevices between the branches. Manipulations of the availability of shelter sites for fishes demonstrated that recruitment and/or early survivorship were strongly limited by the number of refuges. This result was found in six separate carried out during different years and in different seasons. Shelter site availability presumably limits fish populations through its effects on prédation rates. Experimental manipulations of food availability indicated that food does not directly influence settlement or early survivorship of coral reef fishes. However, it is probable that correlations between habitat characteristics and food availability have influenced the evolution of settling preferences.