Reshuffling of the Coral Microbiome during Dormancy

Area of Science:

• Marine biology
• Microbiome research
• Coral ecology

Background:

• Quiescence (dormancy) is a physiological response to stress, observed in many organisms.
• The temperate coral Astrangia poculata exhibits winter quiescence, impacting its physiology.
• Host-microbiome interactions during dormancy are poorly understood, especially in marine invertebrates.

Purpose of the Study:

• To investigate how quiescence affects the microbiome of the temperate coral Astrangia poculata.
• To characterize microbial community shifts before, during, and after winter dormancy.
• To identify key microbial players involved in coral quiescence and microbiome regulation.

Main Methods:

• Utilized 16S rRNA gene sequencing on both active (RNA) and present (DNA) microbial communities.
• Conducted a high-resolution time-series sampling of wild Astrangia poculata before, during, and after quiescence.
• Analyzed microbial community structure and composition changes associated with dormancy.

Main Results:

• Observed a significant restructuring of the coral microbiome during quiescence, with a persistent shift post-dormancy.
• Corals shed copiotrophic microbes and putative pathogens upon entering quiescence.
• Enrichment of bacteria and archaea involved in nitrification (e.g., Nitrosococcales, 'Candidatus Nitrosopumilus') was noted during and after quiescence.

Conclusions:

• Coral quiescence acts as a period for microbiome resetting, shedding opportunistic microbes.
• Nitrifying microbes may provide essential functions, such as nitrate supply, during coral dormancy.
• The predictable dormancy of Astrangia poculata offers a model system to study host-microbial dynamics.