Effective coral restoration must include comprehensive investigations of the targeted coral community that consider all aspects of the coral holobiont—the coral host, symbiotic algae, and microbiome. For example, the richness and composition of microorganisms associated with corals may be indicative of the corals’ health status and thus help guide restoration activities. Potential differences in microbiomes of restoration corals due to differences in host genetics, environmental condition, or geographic location, may then influence outplant success. The objective of the present study was to characterize and compare the microbiomes of apparently healthy Acropora cervicornis genotypes that were originally collected from environmentally distinct regions of Florida’s Coral Reef and sampled after residing within Mote Marine Laboratory’s in situ nursery near Looe Key, FL (USA) for multiple years. By using 16S rRNA high-throughput sequencing, we described the microbial communities of 74 A. cervicornis genotypes originating from the Lower Florida Keys ( n = 40 genotypes), the Middle Florida Keys ( n = 15 genotypes), and the Upper Florida Keys ( n = 19 genotypes). Our findings demonstrated that the bacterial communities of A. cervicornis originating from the Lower Keys were significantly different from the bacterial communities of those originating from the Upper and Middle Keys even after these corals were held within the same common garden nursery for an average of 3.4 years. However, the bacterial communities of corals originating in the Upper Keys were not significantly different from those in the Middle Keys. The majority of the genotypes, regardless of collection region, were dominated by Alphaproteobacteria, namely an obligate intracellular parasite of the genus Ca. Aquarickettsia . Genotypes from the Upper and Middle Keys also had high relative abundances of Spirochaeta bacteria. Several genotypes originating from both the Lower and Upper Keys had lower abundances of Aquarickettsia , resulting in significantly higher species richness and diversity. Low abundance of Aquarickettsia has been previously identified as a signature of disease resistance. While the low- Aquarickettsia corals from both the Upper and Lower Keys had high abundances of an unclassified Proteobacteria, the genotypes in the Upper Keys were also dominated by Spirochaeta . The results of this study suggest that the abundance of Aquarickettsia and Spirochaeta may play an important role in distinguishing bacterial communities among A. cervicornis populations and compositional differences of these bacterial communities may be driven by regional processes that are influenced by both the environmental history and genetic relatedness of the host. Additionally, the high microbial diversity of low- Aquarickettsia genotypes may provide resilience to their hosts, and these genotypes may be a potential resource for restoration practices and management.
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The coral ecosphere: A unique coral reef habitat that fosters coral-microbial interactions
Scleractinian corals are bathed in a sea of planktonic and particle-associated microorganisms. The metabolic products of corals influence the growth and composition of microorganisms, but interactions between corals and
seawater microorganisms are underexplored. We conducted a field-based survey to compare the biomass, diversity, composition, and functional capacity of microorganisms in small-volume seawater samples collected adjacent to
five coral species with seawater collected > 1 m away from the reef substrate on the same reefs. Seawater collected close to corals generally harbored copiotrophic-type bacteria and its bacterial and archaeal composition was influenced by coral species as well as the local reef environment. Trends in picoplankton abundances were variable and either increased or decreased away from coral colonies based on coral species and picoplankton functional group. Genes characteristic of surface-attached and potentially virulent microbial lifestyles were enriched in near coral seawater compared to reef seawater. There was a prominent association between the coral Porites astreoides and the coral symbiont Endozoicomonas, suggesting recruitment and/or shedding of these cells into the surrounding seawater. This evidence extends our understanding of potential species-specific and reef site-influenced microbial
interactions that occur between corals and microorganisms within this near-coral seawater environment that we propose to call the “coral ecosphere.” Microbial interactions that occur within the coral ecosphere could influence recruitment of coral-associated microorganisms and facilitate the transfer of coral metabolites into the microbial food web, thus fostering reef biogeochemical cycling and a linkage between corals and the water column.
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- Award ID(s):
- 1736288
- NSF-PAR ID:
- 10119216
- Date Published:
- Journal Name:
- Limnology and Oceanography
- ISSN:
- 0024-3590
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/lno.11190
