Factors influencing benthic distributional patterns in a near-pristine coral reef ecosystem: Pearl and Hermes Atoll

Abstract

Many factors, both biotic and abiotic, act to structure coral reef communities. In this thesis, I examined potential determinants of coral reef community structure in a near-pristine system, Pearl and Hermes Atoll (PHA); by measuring percent cover of benthic organisms along with herbivorous fish density and biomass, urchin density, nutrient availability, and wave exposure at PHA. Wave exposure and herbivory from both fish and urchins largely explained distributional patterns observed in benthic communities. For instance, when all benthic functional groups were combined in a multivariate analysis, herbivorous fish density combined with wave exposure was identified as having the highest significant correlation with benthic community composition at PHA. Nutrient availability, based on algal tissue nutrient content, however, did not correlate with percent cover of benthic organisms. My results suggest that wave exposure along with top-down mechanisms have primacy over bottom-up mechanisms in an ecosystem free from direct anthropogenic impacts, including fishing.