Benthic marine algae of the Arabian Gulf: a critical review and analysis of distribution and diversity patterns

The Arabian Gulf is an extremely inhospitable and physiologically-stressful environment for marine organisms since they are exposed to the widest range and the highest sea temperatures in the world, as well as high salinities. The present paper assembles and, as far as is possible without extended herbarium study, critically examines the status of all records of three phyla of marine benthic algae (Chlorophyta; Ochrophyta: Phaeophyceae and Xanthophyceae; Rhodophyta) and undertakes a taxonomic and nomenclature revision. All new records for the United Arab Emirates are based on material mostly collected in the 1980s by Dr Frances Dipper and Carolyn Lehmann. The provisional analyses of seaweed diversity and distribution patterns are based on presence-absence data. These are discussed in relation to key environmental variables, length of coastline and proportion of suitable habitats for benthic algae, with attention drawn to gaps due to unevenness of sampling. The diversity of the benthic algal flora is greater in the southern Gulf (Arabian coast) with about 130 species in common to the Iranian and Arabian side. Discussed are factors accounting for the relatively low algal diversity (282 spp.) of the Gulf and these include natural environmental stressors, relatively recent geological age of the basin, isolation and sampling intensity. The benthic algal flora of the Arabian Gulf represents an impoverished subset of that of the Indian Ocean.