Biodiversity and Biogeography of Benthic Marine Algae in the Southwest Pacific, with Specific Reference to Rotuma and Fiji

Abstract

Occurrence and distribution of various species of benthic marine algae in Fiji and Rotuma were investigated, with the resulting floras being subjected to comparison indices (Jaccard) both between themselves and with respect to other neighboring floras in the Southwest Pacific. The Rotuman flora was found to be rather impoverished (106 species) with respect to the Fijian flora (314 species), and the Nauruan and Rotuman flora were most similar, as were the Fijian and Micronesian floras. Dispersal mechanisms for algae in the region were considered, with special attention to the major ocean currents. These currents tend to favor movements of algal species from more northerly locations toward Fiji, and dispersal in the opposite direction seems unlikely. This is assumed to explain the similarities of the Rotuman flora with the Nauruan and Micronesian floras. Peculiar distribution patterns of algae were examined, with one species (Meristotheca procumbens P. Gabrielson & Kraft) being found in Rotuma, Lord Howe Island, and New South Wales (Australia), but not in intervening localities. Ecological and geographical factors are invoked to explain this, although unavailability of detailed checklists from many sites in the region impedes an accurate biogeographical analysis.