Abstract
AimCoral reefs rely on the symbiosis between scleractinian corals and intracellular, photosynthetic dinoflagellates of the genus Symbiodinium making the assessment of symbiont diversity critical to our understanding of ecological resilience of these ecosystems. This study characterizes Symbiodinium diversity around the Arabian Peninsula, which contains some of the most thermally diverse and understudied reefs on Earth.LocationShallow water coral reefs throughout the Red Sea (RS), Sea of Oman (SO), and Persian/Arabian Gulf (PAG).MethodsNext‐generation sequencing of the ITS2 marker gene was used to assess Symbiodinium community composition and diversity comprising 892 samples from 46 hard and soft coral genera.ResultsCorals were associated with a large diversity of Symbiodinium, which usually consisted of one or two prevalent symbiont types and many types at low abundance. Symbiodinium communities were strongly structured according to geographical region and to a lesser extent by coral host identity. Overall symbiont communities were composed primarily of species from clade A and C in the RS, clade A, C, and D in the SO, and clade C and D in the PAG, representing a gradual shift from C‐ to D‐dominated coral hosts. The analysis of symbiont diversity in an Operational Taxonomic Unit (OTU)‐based framework allowed the identification of differences in symbiont taxon richness over geographical regions and host genera.Main conclusionsOur study represents a comprehensive overview over biogeography and molecular diversity of Symbiodinium in the Arabian Seas, where coral reefs thrive in one of the most extreme environmental settings on the planet. As such our data will serve as a baseline for further exploration into the effects of environmental change on host–symbiont pairings and the identification and ecological significance of Symbiodinium types from regions already experiencing ‘Future Ocean’ conditions.
Highlights
Reef-building corals are the foundation of reef ecosystems and provide habitats to a diverse set of marine species, many of which are economically and ecologically important (Roberts et al, 2002)
We identified over 100,000 distinct Symbiodinium Internal Transcribed Spacer 2 (ITS2) sequences in our data, only 977 ITS2 sequences were present at ≥ 1% abundance in at least one sample and 223 ITS2 sequences were present at ≥ 5% abundance in at least one sample, demonstrating the disparity between the total number of ITS2 sequences recovered and their relative proportion
This study utilized next-generation sequencing of the ITS2 marker gene to analyze Symbiodinium composition associated with 46 coral genera and 892 specimens around the Arabian Peninsula
Summary
Reef-building corals are the foundation of reef ecosystems and provide habitats to a diverse set of marine species, many of which are economically and ecologically important (Roberts et al, 2002). These intracellular algae provide up to 95% of the energy needs of the coral host (Falkowski et al, 1984). Symbiodinium species are ecologically diverse, exhibiting discrete associations with different coral hosts that can differ over large geographical scales, depth, season, and exposure to http://wileyonlinelibrary.com/journal/jbi doi:10.1111/jbi.12913 stressors (LaJeunesse et al, 2004, 2010; Finney et al, 2010; Ziegler et al, 2015). Detailed knowledge of Symbiodinium coral pairings is arguably critical to our understanding of ecological resilience of coral reefs
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