Benthic foraminifera in the Arabian Gulf: Biodiversity and geographical trends

Abstract

Utilizing a 60-year history of studies of benthic foraminiferal species distributions in the Arabian Gulf, this study applied a regional-synoptic approach to evaluate the total benthic foraminiferal biodiversity. By compiling, examining, and integrating available data, a conservative analysis yielded 753 benthic foraminiferal species and subspecies belonging to 236 genera, 99 families, 43 superfamilies and 11 orders. These values are comparable to those reported in other basins and are unexpectedly high, considering the extreme conditions of the Gulf. Yet these figures likely represent an underestimation of total diversity, as some areas have been poorly sampled (i.e., south-western part of the Gulf), reference materials are lacking (i.e., a taxonomic atlas), and the difficulty in the identification of taxa at species level has resulted in frequent use of open nomenclature. We contend that these conservative figures nonetheless reflect the actual benthic foraminiferal diversity of the Gulf and reduce the number of modern species left in open nomenclature. The diverse oceanographic, sedimentological and environmental conditions that occur in the Gulf are well mirrored by geographical trends of diversity and in the composition of benthic foraminiferal species. In addition, this paper helps to unify and resolve issues relating to the use of synonyms and taxonomic-name revisions that invariably affect species counts and result in misaligned datasets. This study is part of ongoing research endeavors to establish the much-needed comprehensive knowledge of benthic foraminiferal species and diversity worldwide.