Environment and Co-occurring Native Mussel Species, but Not Host Genetics, Impact the Microbiome of a Freshwater Invasive Species (Corbicula fluminea)

Abstract

The Asian clam Corbicula fluminea (Family: Cyneridae) has aggressively invaded freshwater habitats worldwide, resulting in dramatic ecological changes and declines of native bivalves such as freshwater mussels (Family: Unionidae), one of the most imperiled faunal groups. Despite increases in our knowledge of invasive C. fluminea biology, little is known of how intrinsic and extrinsic factors, including co-occurring native species, influence its microbiome. We investigated the gut bacterial microbiome across genetically differentiated populations of C. fluminea in the Tennessee and Mobile River Basins in the Southeastern United States and compared them to those of six co-occurring species of native freshwater mussels. The gut microbiome of C. fluminea was diverse, differed with environmental conditions and varied spatially among rivers, but was unrelated to host genetic variation. Microbial source tracking suggested that the gut microbiome of C. fluminea may be influenced by the presence of co-occurring native mussels. Inferred functions from 16S rRNA gene data using PICRUST2 predicted a high prevalence and diversity of degradation functions in the C. fluminea microbiome, especially the degradation of carbohydrates and aromatic compounds. Such modularity and functional diversity of the microbiome of C. fluminea may be an asset, allowing to acclimate to an extensive range of nutritional sources in invaded habitats, which could play a vital role in its invasive success.

A multi‐study analysis of gut microbiome data from the blue mussel (Mytilus edulis) emphasises the impact of depuration on biological interpretation

“…Stevick et al (2021) observed that the gut microbiomes of non‐depurated C. virginica vary spatially over their range in Narragansett Bay with important covarying environmental factors such as temperature, salinity, dissolved oxygen and nutrients. Similar effects of the site have been observed in the gut microbiomes of non‐depurated freshwater bivalves (Chiarello et al, 2022; Lawson et al, 2022). The gut microbiomes of non‐depurated bivalves have also been demonstrated to vary temporally over both years (McCauley et al, 2021) and seasons (Akter et al, 2023; Conceição et al, 2021).…”

Identifying potential drivers of distribution patterns of invasive Corbicula fluminea relative to native freshwater mussels (Unionidae) across spatial scales

“…For example, another study of Corbicula habitat preference in the River Minho estuary in Spain showed a positive relationship with Corbicula biomass and the organic matter (OM) content of the sediment (Sousa et al, 2008), but did not mention the presence of mussels. Sediment organic matter produced by mussels via biodeposition may be an important factor influencing the distribution of Corbicula , because OM can be an alternative food source that is accessed through pedal feeding (Hakenkamp & Palmer, 1999; Hakenkamp et al, 2001) and may provide them with beneficial gut microbiota (Chiarello et al, 2022). It seems likely high densities of Corbicula may be supported in habitats with high organic matter content, such as mussel beds (Atkinson & Forshay, 2022; Vaughn & Hakenkamp, 2001).…”

“…Benthic characteristics are an important factor in the distribution of benthic species, including mussels and Corbicula which live buried in benthic habitats and therefore may partition habitat at fine spatial scales. We hypothesized increasing probability of Corbicula occurrence and density in habitats where mussels already exist if habitat requirements OM can be an alternative food source that is accessed through pedal feeding (Hakenkamp & Palmer, 1999;Hakenkamp et al, 2001) and may provide them with beneficial gut microbiota (Chiarello et al, 2022). It seems likely high densities of Corbicula may be supported in habitats with high organic matter content, such as mussel beds (Atkinson & Forshay, 2022;Vaughn & Hakenkamp, 2001).…”

Community‐wide correlations between species richness, abundance and population genomic diversity in a freshwater biodiversity hotspot

“…For population genetics analyses, a subset of individuals (23 species, 3–15 individuals per site per species for species present at a given site) were collected during the quantitative and/or opportunistic sampling and brought back to laboratory on ice where they were flash frozen and stored at −80°C (Chiarello et al, 2022). Mantle tissues were subsequently clipped from partially thawed mussels and stored in molecular grade absolute ethanol at −80°C prior to DNA isolation using Qiagen DNeasy kits (Germantown, Maryland).…”