Diet shapes cold-water corals bacterial communities

Area of Science:

• Marine Biology
• Microbial Ecology
• Coral Reef Science

Background:

• Cold-water coral (CWC) species host unique microbial communities.
• Microbiome composition is hypothesized to reflect host ecological strategies.
• Understanding diet's role in shaping CWC microbiomes is crucial for ecological insights.

Purpose of the Study:

• To investigate if diet composition influences the bacterial communities associated with cold-water corals.
• To compare the microbiomes of two CWC species, Lophelia pertusa and Madrepora oculata, under varying dietary conditions.
• To determine the interplay between host specificity and diet in shaping coral-associated bacterial communities.

Main Methods:

• Experimental feeding of L. pertusa and M. oculata with starved, carnivorous, herbivorous, and mixed diets in aquaria.
• Analysis of both the standing stock (16S rDNA) and active fraction (16S rRNA) of bacterial communities.
• Measurement of storage lipid content in coral tissues to assess metabolic responses to diet.

Main Results:

• Coral microbiomes were found to be specific to the diet provided in both L. pertusa and M. oculata.
• A portion of the microbiome remained specific to each coral species, indicating host influence on microbial composition.
• Different diets differentially impacted coral tissue lipid content, suggesting varied metabolic effects.

Conclusions:

• Diet is a significant driver of bacterial community composition in cold-water corals, alongside host specificity.
• Lophelia pertusa may preferentially consume zooplankton, while Madrepora oculata might utilize phytoplankton and detritus in addition.
• A fraction of the cold-water coral microbiome may represent a food-influenced microbial community, offering new perspectives on coral-microbe interactions.