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Under heat stress, the thermal bleaching percentage of coral holobionts demonstrates interspecific variations that are closely related to the microbiome associated with corals. The ecological implications of community dynamics and interactions between Symbiodiniaceae and fungi with respect to thermal bleaching sensitivity of corals remain unknown.
A new study provides insight into the role of microbes and their interaction as drivers of interspecific differences in thermal bleaching of corals.
The study’s lead author, Biao Chen, Ph., assistant professor at the China Coral Reef Research Center, College of Marine Sciences, Guangxi University, said: “The diversity, community dynamics and interaction of coral-associated microorganisms play important roles in the health status and response pattern to climate change of coral reefs. “We urge the creation of broader coral reef microbial datasets on a global scale and recommend interdisciplinary research spanning ecology, marine chemistry, physical oceanography, and microbiomics.”
The effects of global warming have caused significant biodiversity losses and thermal bleaching of corals in coral reef ecosystems. Coral reefs, also known as coral holobionts, consist of animal hosts, endosymbiotic Symbiodiniaceae (a family of marine dinoflagellates), bacteria, archaea, fungi and viruses.
During heat waves, corals have demonstrated considerable interspecific variability in the degree of bleaching and heat tolerance. The relationships between fungi and Symbiodiniaceae on variations in coral heat tolerance remain unknown, although scientists are aware that the coral-associated microbiome is critical in controlling the environmental tolerance of coral reefs.
To fill this knowledge gap, scientists set out to study Huangyan Island, a reef in the South China Sea with a higher risk of coral bleaching. This selection was deliberate due to the noticeably higher sea surface temperatures of the coral reefs surrounding Huangyan Island compared to the Xisha Islands at the same latitude.
The 18 coral species the researchers focused on are widely dispersed throughout the tropical regions of the South China Sea. Their study focused on determining the extent of bleaching during the notable coral bleaching event that took place there in 2020. As a result of this research, a classification system was developed for the susceptibility of these 18 coral species to heat bleaching. .
In the last phase of the study, the scientists focused on the dynamic interactions that occur between coral organisms, particularly in the fungal and Symbiodiniaceae communities. They discovered possible relationships between heat bleaching susceptibility classification of corals and ecological markers of Symbiodiniaceae and fungal populations.
The study found that the dominant group in the coral microbial community on Huangyan Island was the heat-tolerant Symbiodiniaceae. An increase in pathogen abundance and fungal variety is closely correlated with an increase in coral sensitivity to thermal bleaching.
By building an interaction network between Symbiodiniaceae and fungi in corals, the researchers determined that limiting fungal parasitism and fostering strong resilience of the interaction network would help the corals’ heat acclimation.
Chen saying, “Our study highlights the ecological effects of microbiome dynamics and interactions between Symbiodiniaceae and fungi on thermal bleaching susceptibility of corals, providing insights into the role of microorganisms and their interaction as drivers of interspecific differences in bleaching. temperature of corals”.
“The study is prepared to establish a preliminary basis to delve deeper into the response patterns of microorganisms associated with corals to global warming.”
Magazine reference:
- Biao Chen, Yuxin Wei et al. Microbiome dynamics and the interaction of endosymbiotic Symbiodiniaceae and fungi are associated with thermal bleaching susceptibility of coral holobionts. Applied and Environmental Microbiology. DOI: 10.1128/aem.01939-23