A brand new study provides insight into the role of microbes and their interactions as drivers of interspecific differences in coral thermal bleaching. The study was published this week within the Journal of the American Society for Microbiology.
“The diversity, community dynamics and interactions of coral-associated microorganisms play an important role in the health status and response patterns of coral reefs to climate change,” said Biao Chen, Ph.D., assistant professor on the Coral Reef Research Center. School of Marine Science at Guangxi University, China. “We urge the creation of more comprehensive coral reef microbial datasets globally and recommend the initiation of interdisciplinary research involving ecology, marine chemistry, physical oceanography and microbiomics.” The creation of the datasets goals to unveil the critical role of microorganisms in the difference of coral reef ecosystems amid the challenges posed by global warming, the researchers say.
The effects of worldwide warming have resulted in significant lack of biodiversity and coral thermal bleaching in coral reef ecosystems. Coral reefs, also referred to as coral holobionts, contain animal hosts, endosymbiotic Symbiodiniaceae (a family of marine dinoflagellates), bacteria, archaea, fungi, and viruses. Corals have shown significant variation in bleaching severity and warmth tolerance during heat wave events. While researchers know that the coral-associated microbiome plays a vital role in regulating the environmental tolerance of coral reefs, the interaction between Symbiodiniaceae and fungi on differences in coral heat tolerance is unclear.
To fill this information gap, Chen set out to review Huangyan Island, a reef within the South China Sea that's at high risk of coral bleaching. This selection was made deliberately, attributable to the significantly higher sea surface temperature of the coral reefs around Huangyan Island in comparison with the Xisha Islands at the identical latitude.
The researchers targeted 18 coral species widely distributed within the tropical regions of the South China Sea. Their research focused on assessing the extent of bleaching through the major coral bleaching event that occurred there in 2020. This examination resulted in a classification system for the sensitivity of those 18 coral species to heat bleaching.
In the ultimate phase of the research, the investigators examined the dynamic interactions inside coral organisms, particularly the communities of Symbiodiniaceae and fungi. They identified potential correlations between environmental indicators of Symbiodiniaceae and fungal communities and rating of coral heat bleaching sensitivity.
The study found that the microbial community of corals in Huangyan Island is dominated by heat-tolerant symbiodinaceae. Increased fungal diversity and pathogen abundance are closely related to higher susceptibility of corals to thermal bleaching. The researchers modeled an interaction network between Symbiodiniaceae and fungi in corals, indicating that limiting the flexibleness of fungal parasites and powerful interaction networks would promote corals' warming adaptation.
“Our study sheds light on the environmental impact of microbiome dynamics and interactions between Symbiodiniaceae and fungi on susceptibility to coral thermal bleaching, highlighting the role of microorganisms and their interactions as drivers of variation in coral thermal bleaching. provides insight into,” Chen said. “The study sets out to ascertain an initial basis for exploring global warming response patterns of coral-associated microorganisms.”