Comparison of microbiomes of cold-water corals Primnoa pacifica and Primnoa resedaeformis, with possible link between microbiome composition and host genotype

Dawn B. Goldsmith,Michael A. Gray,Christina A. Kellogg,Steve W. Ross,Robert P. Stone,Sandra D. Brooke,Cheryl L. Morrison,Rhian G. Waller

doi:10.1038/s41598-018-30901-z

Abstract

Cold-water corals provide critical habitats for a multitude of marine species, but are understudied relative to tropical corals. Primnoa pacifica is a cold-water coral prevalent throughout Alaskan waters, while another species in the genus, Primnoa resedaeformis, is widely distributed in the Atlantic Ocean. This study examined the V4-V5 region of the 16S rRNA gene after amplifying and pyrosequencing bacterial DNA from samples of these species. Key differences between the two species’ microbiomes included a robust presence of bacteria belonging to the Chlamydiales order in most of the P. pacifica samples, whereas no more than 2% of any microbial community from P. resedaeformis comprised these bacteria. Microbiomes of P. resedaeformis exhibited higher diversity than those of P. pacifica, and the two species largely clustered separately in a principal coordinate analysis. Comparison of P. resedaeformis microbiomes from samples collected in two submarine canyons revealed a significant difference between locations. This finding mirrored significant genetic differences among the P. resedaeformis from the two canyons based upon population genetic analysis of microsatellite loci. This study presents the first report of microbiomes associated with these two coral species.

Highlights

Tropical corals provide critical habitat for a vast number of marine species[1], and recent expansion of deep-water marine research has revealed that cold-water coral ecosystems are abundant and critical to marine biodiversity[2]
The corals were sampled in two different ocean basins: P. pacifica samples were collected from one location in the Gulf of Alaska in the Pacific Ocean, and P. resedaeformis samples were collected from two submarine canyons in the North Atlantic Ocean, approximately 140 km apart
All but one of the P. pacifica samples were dominated by Chlamydiae, much as Mediterranean gorgonian microbiomes are dominated by Endozoicomonas, whereas the P. resedaeformis samples obtained from the deep sea showed much more diversity (Fig. 2, Table 2)

Summary

Introduction

Tropical corals provide critical habitat for a vast number of marine species[1], and recent expansion of deep-water marine research has revealed that cold-water coral ecosystems are abundant and critical to marine biodiversity[2]. Two species of Primnoa corals were sampled for the purpose of characterizing and comparing their microbial communities. The corals were sampled in two different ocean basins: P. pacifica samples were collected from one location in the Gulf of Alaska in the Pacific Ocean, and P. resedaeformis samples were collected from two submarine canyons in the North Atlantic Ocean, approximately 140 km apart. In light of reports showing that cold-water corals have conserved bacterial communities[13,20], we hypothesized that the microbiomes of Primnoa corals contain core bacterial species common to all members of the genus. Collection of P. resedaeformis from separate submarine canyons allowed us to examine whether corals of the same species in different locations contained distinctive microbial communities. When significant microbiome variation between canyons was detected, we analyzed microsatellite loci of the P. resedaeformis samples to examine whether host population genetics could be an underlying factor

Methods

Results

Discussion

Conclusion