title: Diversity and distribution of eukaryotic microbes in and around a brine pool adjacent to the Thuwal cold seeps in the Red Sea.
abstract: A hypoxic/suboxic brine pool at a depth of about 850 m was discovered near the Thuwal cold seeps in the Red Sea. Filled with high concentrations of hydrogen sulfide and ammonia, such a brine pool might limit the spread of eukaryotic organisms. Here, we compared the communities of the eukaryotic microbes in a microbial mat, sediments and water samples distributed in 7 sites within and adjacent to the brine pool. Taxonomic classification of the pyrosequenced 18S rRNA amplicon reads showed that fungi highly similar to the species identified along the Arabic coast were almost ubiquitous in the water and sediment samples, supporting their wide distribution in various environments. The microbial mat displayed the highest species diversity and contained grazers and a considerable percentage of unclassified species. Phylogeny-based methods revealed novel lineages representing a majority of the reads from the interface between the sea water and brine pool. Phylogenetic relationships with more reference sequences suggest that the lineages were affiliated with novel Alveolata and Euglenozoa inhabiting the interface where chemosynthetic prokaryotes are highly proliferative due to the strong chemocline and halocline. The brine sediments harbored abundant species highly similar to invertebrate gregarine parasites identified in different oxygen-depleted sediments. Therefore, the present findings support the uniqueness of some microbial eukaryotic groups in this cold seep brine system.
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology Hong Kong, China ; Sanya Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences San Ya, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology Hong Kong, China.
authors.forename: Wei Peng
authors.initials: WP
authors.lastname: Zhang
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology Hong Kong, China.
authors.forename: Hui Luo
authors.initials: HL
authors.lastname: Cao
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology Hong Kong, China.
authors.forename: Chun Shum
authors.initials: CS
authors.lastname: Shek
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology Hong Kong, China.
authors.forename: Ren Mao
authors.initials: RM
authors.lastname: Tian
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology Hong Kong, China.
authors.forename: Yue Him
authors.initials: YH
authors.lastname: Wong
authors.affiliation: Coastal and Marine Resources Core Laboratory, King Abdullah University of Science and Technology Jeddah, Saudi Arabia.
authors.forename: Zenon
authors.initials: Z
authors.lastname: Batang
authors.affiliation: Coastal and Marine Resources Core Laboratory, King Abdullah University of Science and Technology Jeddah, Saudi Arabia.
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Al-Suwailem
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology Hong Kong, China.
authors.forename: Pei-Yuan
authors.initials: PY
authors.lastname: Qian
keywords: 18S rRNA; Eukaryotic microbes; brine pool; classification; cold seep