Coral microbiomes are structured by environmental gradients in deep waters

Area of Science:

• Marine Biology
• Microbial Ecology
• Genomics

Background:

• Coral-associated microbiomes exhibit significant variability across colonies and locations, influencing host health.
• Deep-sea corals inhabit vast ranges, yet the full extent of their microbiome variability remains largely unexplored.
• This study investigates the microbiomes of four octocoral species in the Gulf of Mexico's mesophotic and bathyal zones.

Purpose of the Study:

• To characterize the microbiomes of deep-sea octocorals across their geographic ranges.
• To assess microbiome differentiation influenced by depth, geographic location, and host genotype.
• To identify environmental factors shaping deep-sea coral microbiome structure and function.

Main Methods:

• 16S rRNA gene metabarcoding was employed to analyze microbial communities.
• RAD-sequencing was used to determine host coral genetic variation.
• Sampling spanned depths from 53 to 2224 meters across the northern Gulf of Mexico.

Main Results:

• Microbiome composition was significantly influenced by coral species, depth, and geographic location.
• Depth emerged as the primary environmental driver of microbiome structure within species.
• Host genotype, bottom temperature, and surface productivity partially explained microbiome variations.

Conclusions:

• Deep-sea coral microbiomes display substantial range-wide variation linked to environmental conditions, particularly depth.
• Depth influences mesophotic and deep-sea coral ecology, extending to their associated microbiomes with potential functional impacts.
• Microbe distribution data, including potential pathogens, can inform restoration strategies post-Deepwater Horizon oil spill.