Figure 1

Global distribution of Porites spp.–Symbiodinium associations. (a) Schematic depiction of the sampling sites and oceanographic conditions in the PAG and the western Gulf of Oman. Seasonally averaged (July to September) surface salinity fields (coloured contour plot) and currents (black arrows) are overlaid using the 10-year model output (climatological run) from Yao and Johns (2010). The major surface inflow and deep outflow currents that connect the PAG with the Gulf of Oman are denoted by the thick arrows coloured according to their prevailing salinity. A minor coastal surface outflow (Johns et al., 1999) is represented by a solid white arrow. The sampling sites of the present study in the southern PAG, Musandam and the Gulf of Oman are highlighted by coloured filled circles. The percentage of Porites spp. (P. lobata, P. lutea and P. harrisoni) colonies that harbour C3 (determined by DGGE; Supplementary Table S2) in the different regions is colour coded in the figure and defined in the legend. The total number of analysed colonies is indicated in brackets (n), sample sizes of the individual locations are detailed in Supplementary Figure S2. Literature data for reefs elsewhere are specified in Supplementary Table S3. Salinity and current imagery was kindly provided by W.E. Johns, University of Miami. (b) Global distribution of P. lobata/P. lutea associations with Symbiodinium cladal/subcladal types (as defined by the internal transcribed spacer 2 (ITS2) region of the Symbiodinium rDNA operon). Pie chart size and filled colours represent the number of individual coral colony associations identified and ITS2 cladal/subcladal type, respectively. Integers within the pie charts refer to the sampling regions (Supplementary Table S3). Data for the PAG (G) and Musandam/Gulf of Oman (M/GO) from the present study are included for comparison (Supplementary Table S2).