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Abstract Freshwater mussels are important for nutrient cycling and ecosystem health as they filter feed on their surrounding water. This filter feeding makes these bivalves especially sensitive to conditions in their environment. Gut microbial communities (microbiomes) have been recognised as important to both host organism and ecosystem health; however, how freshwater mussel microbiomes are organised and influenced is unclear.In this study, the gut bacterial microbiome of Threeridge mussel,Amblema plicata, was compared across two river basins, five rivers, and nine local sites in the south‐eastern U.S.A. Mussel gut tissue was dissected, DNA extracted, and the microbiome characterised by high throughput sequencing of the V4 region of the 16S ribosomal RNA gene.Planctomycetes, Firmicutes, and Cyanobacteria were the most common bacterial phyla within the guts of all sampledA.plicata. However, the relative abundances of these major bacterial phyla differed between mussels sampled from different rivers and river basins, as did the relative abundance of specific bacterial operational taxonomic units (OTUs). Despite these differences, a core microbiome was identified across all mussels, with eight OTUs being consistent members of theA.plicatamicrobiome at all sites, the most abundant OTU identifying as a member of the family Planctomycetaceae. Geographic distance between sites was not correlated with similarity in the structure of the gut microbiome, which was more related to site physicochemistry.Overall, these results suggest that while physicochemical conditions affect the composition of transient bacteria in the Threeridge mussel gut microbiome, the core microbiome is largely unaffected, and a portion of theA.plicatamicrobiome is retained regardless of the river system.How long transient bacteria remain in the gut, and to what extent these transient microbes aid in host function is still unknown. Core microbiota have been found to aid in multiple functions within animal hosts, and within freshwater mussels this core microbiome may aid in nutrient processing and cycling. Therefore, it is important to look at both transient and core microbes when studying the structure of freshwater invertebrate microbiomes.
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Introduction into natural environments shifts the gut microbiome of captivity-raised filter-feeding bivalves
Abstract The gut microbiome is influenced by host species and the environment, but how the environment influences the microbiome of animals introduced into a new ecosystem has rarely been investigated. Freshwater mussels are aquatic fauna, with some threatened or endangered species propagated in hatcheries and introduced into natural systems as part of conservation efforts. The effects of the environment on the freshwater mussel gut microbiome were assessed for two hatchery-propagated species (Lampsilis ovata, Lampsilis ornata) introduced into rivers within their natural range. Mussels were placed in rivers for 8 weeks, after which one subset was collected, another subset remained in that river, and a third subset was reciprocally transplanted to another river in the same river basin for a further 8 weeks. Gut microbiome composition and diversity were characterized for all mussels. After the initial 8 weeks, mussels showed increased gut bacterial species richness and distinct community composition compared to hatchery mussels, but gut microbiome diversity then decreased for mussels that remained in the same river for all 16 weeks. The gut bacterial community of mussels transplanted between rivers shifted to resemble that of mussels placed initially into the recipient river and that remained there for the whole study. All mussels showed high proportions of Firmicutes in their gut microbiome after 8 weeks, suggesting an essential role of this phylum in the gut of Lampsilis species. These findings show that the mussel gut microbiome shifts in response to new environments and provide insights into conservation strategies that involve species reintroductions.
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- Award ID(s):
- 1831531
- PAR ID:
- 10553978
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- ISME Communications
- Volume:
- 4
- Issue:
- 1
- ISSN:
- 2730-6151
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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