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Even though seaweeds have been recognized as key players in the ocean-to-atmosphere transfer of iodine in other parts of the world, there is a complete lack of knowledge about iodine accumulation in seaweeds of the Arabian Gulf. Similarly, very little is known about fluorine in seaweeds, anywhere in the world. Given that the Arabian Gulf is of particular interest due to being an extreme environment, featuring some of the highest temperatures and salinities observed in any marine water body worldwide, this study endeavoured to conduct a preliminary survey of iodine and fluorine levels in 11 of the most common seaweed species in the region, supported by morphological and molecular (DNA barcode)-based identification. Iodine was determined by inductively-coupled plasma-mass spectrometry, while ion chromatography was employed for analysis of fluoride. Species surveyed included Iyengaria stellata, Padina boergesenii, Chondria sp.Dictyota dichotoma, Colpomenia sinuosa, Feldmannia indica,Codium papillatum, Sargassum ilicifolium, S. ilicifolium var. acaraeocarpum, Sargassum asperifolium and Sargassum aquifolium. The findings of S. ilicifolium and S. ilicifolium var. acaraeocarpum reported here are new records both for Kuwait and the Arabian Gulf. P. boergesenii and D. dichotoma are new records for Kuwait.

Biofilms harboring simultaneously anoxygenic and oxygenic phototrophic bacteria, diazotrophic bacteria, and hydrocarbon-utilizing bacteria were established on glass slides suspended in pristine and oily seawater. Via denaturing gradient gel electrophoresis analysis on PCR-amplified rRNA gene sequence fragments from the extracted DNA from biofilms, followed by band amplification, biofilm composition was determined. The biofilms contained anoxygenic phototrophs belonging to alphaproteobacteria; pico- and filamentous cyanobacteria (oxygenic phototrophs); two species of the diazotroph Azospirillum; and two hydrocarbon-utilizing gammaproteobacterial genera, Cycloclasticus and Oleibacter. The coexistence of all these microbial taxa with different physiologies in the biofilm makes the whole community nutritionally self-sufficient and adequately aerated, a condition quite suitable for the microbial biodegradation of aquatic pollutant hydrocarbons.

The taxonomy, classification, and phylogenetic relationships of the brown seaweed genus Iyengaria with other members of the family Scytosiphonaceae remain poorly understood. In this study, we addressed some problems in the systematics (taxonomic and classification status) and phylogenetic position of Iyengaria based on our studies on the generitype Iyengaria stellata from Kuwait and South Africa. We confirm that I. stellata is conspecific with Colpomenia capensis based on molecular and morpho-anatomical data and that the species has a disjunct distribution within the Indian Ocean. Also, the distinguishing features of two Iyengaria species (I. nizamuddinii and 'I. lobocylindrica') described from Karachi, Pakistan, are within the morphological range of I. stellata. Hence, these two taxa are considered here as junior heterotypic synonyms of I. stellata. Our molecular phylogenetic analyses suggested the polyphyly of the genus Iyengaria, with the recently described Iyengaria quadriseriata from India forming close associations with Rosenvingea intricata. As such, we remove I. quadriseriata from the genus Iyengaria and relegate it as a synonym of R. intricata. Consequently, by recognizing only one species, our proposals considerably reduce the species diversity in the genus. Moreover, our culture studies suggested that I. stellata exhibits an alternation of heteromorphic generations, similar to other species in the Scytosiphonaceae. Under culture conditions, I. stellata also produced plurangia on microthalli, confirming its affinity with other phylogenetically close relatives in the 'Hydroclathrus group' of the family Scytosiphonaceae such as Colpomenia, Rosenvingea, and Chnoospora.