Microbiome associated with six corals species along thermal gradients in the northern Red Sea. Coral microbiome (endosymbiotic dinoflagellates and 16S rRNA bacterial community)

This work investigated the microbiome composition (endosymbiotic dinoflagellate and bacterial community) of six coral species across five sites along the northern Red Sea (spanning 4˚ of latitude) representing a thermal gradient. Samples were collected in February/March 2013 and the selected sites were; Abo Ghalloum (28.6147˚N, 34.5604˚E; Gulf of Aqaba), Ras Mohamed (27.7305˚N, 34.2691˚E; Sinai Peninsula), (3) Abo Galawa (27.3157˚N, 33.8097˚E), (4) Meritte (27.2485˚N, 33.849°E) at Hurghada, and (5) Wadi El Gemal (24.6988˚N, 35.1327˚E) at the southern Egyptian coast. Six coral species representing different coral growth forms: massive (Porites nodifera, Favia favus), and branching (Pocillopora damicornis, Seriatopora hystrix) hard coral, as well as soft corals (Xenia umbellata, Sarcophyton trocheliophorum) were sampled at each site from shallow (2-5m) and deep (15-18m) reef slopes. Overall, three types of samples were collected; 1) three replicates x five sites x six species x two depths samples of coral tissue (total n=164) to identify symbiont ITS2 gene using denaturation gradient gel electrophoresis (DGGE). 2) At each sampled coral colony, three replicates x five sites x six species x two depths samples of surface mucus layer (total n=141) were collected to identify bacterial community using metabarcoding of 16S rRNA genes on Illumina HiSeq next-generation sequencing platform. 3) three replicates of water samples x 2 depth x 5 sites (total n=23) were also collected as reference bacterial 16S rRNA samples.