Reef environments shape microbial partners in a highly connected coral population.

Area of Science:

• Marine biology
• Coral reef ecology
• Microbial ecology

Background:

• Coral holobiont health is influenced by associated microbial communities.
• Environmental context significantly shapes coral-associated algal and bacterial taxa.
• Limited research connects coral host genetics with microbial partners across diverse environments.

Purpose of the Study:

• To investigate how reef zones and host genetics influence algal and bacterial communities in a coral population.
• To understand the scale at which environmental factors structure holobiont partners.
• To explore potential genotype-by-genotype interactions within the coral holobiont.

Main Methods:

• 2b-RAD sequencing for coral host genotyping.
• Metabarcoding of ITS2 (algal) and 16S (bacterial) regions.
• Comparison of microbial communities across different reef zones (fore reef vs. back reef).

Main Results:

• Reef zones significantly structure algal and bacterial communities in *Acropora hyacinthus*.
• Fore reef algal communities exhibited higher diversity than back reef communities.
• Coral host genetic diversity positively correlated with bacterial diversity in fore reef environments.

Conclusions:

• Local reef conditions are critical in shaping coral holobiont composition.
• Distinct host-microbial partnerships may arise due to environmental pressures.
• These findings have implications for the fitness and adaptation of coral populations in changing environments.