The diagnosis of bacterial disease in freshwater unionid mussels has been hindered by a lack of baseline information regarding the microbial communities associated with these animals. In this study, we cultured and identified bacteria from the hemolymph of stable mussel populations from the upper Mississippi River basin and compared results to mussel populations associated with a mortality event in the Clinch River, VA and TN. Several bacterial genera were consistently identified across mussel species and locations, appearing to be part of the natural bacterial flora. One noteworthy isolate was identified from the Clinch River. Yokenella regensbergei was found with relatively high prevalence during the mortality event but was absent from post-mortality samples. Its role, if any, in the mortality event is unknown and deserves further investigation. We suggest that future studies of freshwater mussel health utilize hemolymph samples due to its relative disconnect with the aquatic environment, role in the circulatory system and nonlethal nature of collection.

We investigated the cultureable bacterial communities in the native freshwater mussel faunal in the Clinch River, VA/TN during mussel mortality events in 2018, 2019 and 2020 and examine the spatial and temporal distribution of bacterial genera among Pheasantshells and six other unionid species.

We investigated the cultureable bacterial communities in the native freshwater mussel faunal in the Clinch River, VA/TN during mussel mortality events in 2018, 2019 and 2020 and examine the spatial and temporal distribution of bacterial genera among Pheasantshells and six other unionid species.

Longstanding taxonomic uncertainties have limited conservation efforts for species currently assigned to the freshwater mussel genus Alasmidonta. Here, we present mitochondrial and nuclear DNA sequence data needed to assess the genus- and species-level taxonomy of Alasmidonta. These molecular data allowed us to test whether cryptic diversity exists within Alasmidonta and whether A. triangulata and A. arcula are distinct species. Details associated with specimens and DNA sequence data are provided here to provide a foundation for future research on Alasmidonta and give conservation agencies greater confidence in the findings of our work.

Longstanding taxonomic uncertainties have limited conservation efforts for species currently assigned to the freshwater mussel genus Alasmidonta. Here, we present mitochondrial and nuclear DNA sequence data needed to assess the genus- and species-level taxonomy of Alasmidonta. These molecular data allowed us to test whether cryptic diversity exists within Alasmidonta and whether A. triangulata and A. arcula are distinct species. Details associated with specimens and DNA sequence data are provided here to provide a foundation for future research on Alasmidonta and give conservation agencies greater confidence in the findings of our work.

Invasion of North American waters by Dreissena polymorpha and D. rostriformis bugensis has resulted in declines in native North American Unionoida mussels. Dreissenid mussels biofoul unionid mussels in large numbers and interfere with unionid movement, acquisition of food and ability to open and close their shells. Initial expectations for the Great Lakes were that unionids would be extirpated where they co-occur with dreissenids, but recently adult and juvenile unionids have been found alive in several apparent refugia. These unionid populations may persist due to reduced dreissenid biofouling in these areas, and/or due to processes that remove biofoulers. For example, locations inaccessible to veligers may reduce biofouling and habitats with soft substrates may allow unionids to burrow and thus remove dreissenids. Here, biofouling was measured by deploying caged unionid mussels (Lampsilis siliquoidea) at 36 sites across the western basin of Lake Erie to assess spatial variation in biofouling and to identify other areas that might promote the persistence or recovery of native unionid mussels. Biofouling ranged from 0.03 – 26.33 g per mussel, reached a maximum in the immediate vicinity of the Maumee rivermouth, and appeared to primarily consist of dreissenid mussels. A known mussel refugium in the vicinity of a power plant near the Maumee rivermouth actually exhibited very high biofouling rates, suggesting low dreissenid colonization is unlikely to be the primary cause of unionid survival in this refugium. The southern nearshore area of Lake Erie, near another refugium, also had very low biofouling. A large stretch of the western basin appeared to have low biofouling rates and muddy substrates, raising the possibility that these open water areas could support remnant and returning populations of unionid mussels.

Invasion of North American waters by Dreissena polymorpha and D. rostriformis bugensis has resulted in declines in native North American Unionoida mussels. Dreissenid mussels biofoul unionid mussels in large numbers and interfere with unionid movement, acquisition of food and ability to open and close their shells. Initial expectations for the Great Lakes were that unionids would be extirpated where they co-occur with dreissenids, but recently adult and juvenile unionids have been found alive in several apparent refugia. These unionid populations may persist due to reduced dreissenid biofouling in these areas, and/or due to processes that remove biofoulers. For example, locations inaccessible to veligers may reduce biofouling and habitats with soft substrates may allow unionids to burrow and thus remove dreissenids. Here, biofouling was measured by deploying caged unionid mussels (Lampsilis siliquoidea) at 36 sites across the western basin of Lake Erie to assess spatial variation in biofouling and to identify other areas that might promote the persistence or recovery of native unionid mussels. Biofouling ranged from 0.03 – 26.33 g per mussel, reached a maximum in the immediate vicinity of the Maumee rivermouth, and appeared to primarily consist of dreissenid mussels. A known mussel refugium in the vicinity of a power plant near the Maumee rivermouth actually exhibited very high biofouling rates, suggesting low dreissenid colonization is unlikely to be the primary cause of unionid survival in this refugium. The southern nearshore area of Lake Erie, near another refugium, also had very low biofouling. A large stretch of the western basin appeared to have low biofouling rates and muddy substrates, raising the possibility that these open water areas could support remnant and returning populations of unionid mussels.

These datasets provide geographic sampling information for Bathymodiolin mussel samples collected from three cold seep sites off the mid-Atlantic U.S. coast, northwestern Atlantic Ocean. Also included are GenBank accession numbers for mitochondrial gene sequences (COI and ND4) used to identify the mussel species and GenBank accession numbers for BioProject containing 16S metabarcoding sequence data used to identify gill symbionts in mussels.

These datasets provide geographic sampling information for Bathymodiolin mussel samples collected from three cold seep sites off the mid-Atlantic U.S. coast, northwestern Atlantic Ocean. Also included are GenBank accession numbers for mitochondrial gene sequences (COI and ND4) used to identify the mussel species and GenBank accession numbers for BioProject containing 16S metabarcoding sequence data used to identify gill symbionts in mussels.

Here we provide public access to three DNA sequence alignments (COI, ND1, ITS1) and details on all specimens utilized in Keogh et al. (in review).