title: Dongsha Atoll: A potential thermal refuge for reef-building corals in the South China Sea.
abstract: Dongsha Atoll (also known as the Pratas Islands), the northernmost atoll in the South China Sea, experiences two contrasting physical phenomena: repetitive anomalies of the sea surface temperature exceeding the coral bleaching threshold and regular effects of the world's strongest internal waves resulting in the rhythmic upwelling of cold deep waters at the outer reef slopes of the atoll. This unique combination may result in significant differences in coral species composition and structure between the lagoon and forereef. Surveys conducted in August-September 2016 at 12 study sites in the 2-15 m depth range at Dongsha Atoll revealed a clear spatial separation between 'thermally-susceptible' stony coral genera, including Acropora, Pocillopora and Montipora, which mainly inhabited the forereef, and 'thermally-resistant' genera, including massive Porites, foliaceous Echinopora, Pavona and Turbinaria, which mainly resided in the lagoon. The mean coral cover and species richness on the forereef were respectively 1.8 and 1.4 times higher than those in the lagoon (61.3% and 98 species on the forereef vs. 34.2% and 69 species in the lagoon). Coral mortality rates, expressed as the ratio of dead to live stony corals, showed the same pattern (0.4 in the lagoon vs. 0.009 on the forereef). Furthermore, in a laboratory experiment, 'thermally-susceptible' taxa from the lagoon, (e.g. Pocillopora verrucosa and P. damicornis), exhibited higher resistance to bleaching than did their counterparts from the forereef. The present findings indicate that Dongsha Atoll is a potential thermal refuge for reef-building corals in the northern South China Sea and reveal the development of resilience and resistance to bleaching in coral communities of the lagoon.
authors.affiliation: Samara State Educational University, Samara 443090, Russia. Electronic address: konsttkachenko@gmail.com.
authors.forename: Konstantin S
authors.initials: KS
authors.lastname: Tkachenko
authors.affiliation: National Sun Yat-sen University, Kaohsiung 80424, Taiwan, ROC.
authors.forename: Keryea
authors.initials: K
authors.lastname: Soong
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D002681:China; D057894:Coral Reefs; D004784:Environmental Monitoring; D006358:Hot Temperature; D012623:Seawater / Q000737:chemistry*; D013696:Temperature
keywords: Coral resilience and resistance; Dongsha Atoll; Thermal anomalies; Upwelling