Spatial Homogeneity of Bacterial Communities Associated with the Surface Mucus Layer of the Reef-Building Coral Acropora palmata

Dustin W Kemp,Adam R Rivers,Keri M Kemp,John P Wares,Erin K Lipp,James W Porter,Mónica Medina

doi:10.1371/journal.pone.0143790

Dustin W Kemp, Adam R Rivers + Show 5 more

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https://doi.org/10.1371/journal.pone.0143790

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Journal: PloS one	Publication Date: Dec 14, 2015
Citations: 21	License type: CC BY 4.0

Affiliation: University of Georgia, Joint Genome Institute

Abstract

Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral Acropora palmata in the Florida Keys. Samples were taken from three spatially distinct colony regions—uppermost (high irradiance), underside (low irradiance), and the colony base—representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of A. palmata has been studied. Homogeneity in the microbiome of A. palmata contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of A. palmata. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.

Highlights

Reef-building corals host diverse assemblages of internal and external microbiota [1,2] that collectively make up the coralPLOS ONE | DOI:10.1371/journal.pone.0143790 December 14, 2015Acropora palmata Surface Mucus Layer Homogeneity holobiont [3,4,5]
Bacteria found within coral surface mucus layer (SML) are essential components of the coral holobiont and have crucial roles in nutrient cycling and disease prevention [4,5,6]
We obtained 64,022 high-quality 16S rRNA gene pyrosequencing reads from three regions located on Acropora palmata colonies, adjacent sediments, and seawater 1 m above coral colonies (Fig 1)

Summary

Introduction

Reef-building corals host diverse assemblages of internal and external microbiota (i.e., archaea, bacteria, cyanobacteria, fungi, protists, and viruses) [1,2] that collectively make up the coralPLOS ONE | DOI:10.1371/journal.pone.0143790 December 14, 2015Acropora palmata Surface Mucus Layer Homogeneity holobiont [3,4,5]. Reef-building corals host diverse assemblages of internal and external microbiota (i.e., archaea, bacteria, cyanobacteria, fungi, protists, and viruses) [1,2] that collectively make up the coral. Bacteria found within coral surface mucus layer (SML) are essential components of the coral holobiont and have crucial roles in nutrient cycling and disease prevention [4,5,6]. Given the potential for rapid turnover of the corals’ SML bacterial community and the potential importance that this community plays in metabolism and defense against water-borne pathogens, one might predict high variance in composition and abundance of these communities across such topologically complex forms

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