Freshwater mussels of the order Unionida are among the most endangered animal groups globally, but the causes of population declines are often enigmatic with little known about the role of disease. In 2018, we collected wild adult pheasantshell (Actinonaias pectorosa) and mucket (Actinonaias ligamentina) during an epidemiologic survey investigating an ongoing mussel mass mortality event in the Clinch River, USA. Histopathology and transmission electron microscopy showed a novel microsporidian parasite primarily infecting the ovary of pheasantshell. Sequencing of the small subunit rRNA gene produced a 1333 bp sequence with greatest similarity to Pseudonosema cristatellae (AF484694.1; 86.36%; e-value = 0), a microsporidium infecting the freshwater bryozoan (Cristatella mucedo). Microsporidia were observed in 65% (17/26) of the examined female pheasantshell (A. pectorosa) and in no (0/2) female mucket (A. ligamentina), and occurred at mortality and non-mortality sites. Our findings indicate that a novel parasite, Microsporidium clinchi n. sp., is present in pheasantshell in the Clinch River, USA, and while likely not a cause of mass mortality, could reduce fecundity and recruitment in this declining population and threaten the success of reintroductions. Surveillance for M. clinchi n. sp. and evaluation of brood stock and their progeny for microsporidia would therefore be prudent.

During an epidemiologic survey following a mortality event of freshwater mussels in 2018 in the Embarrass River, Wisconsin, USA, we identified a novel microsporidian parasite in the ovary of mucket (Actinonaias ligamentina), plain pocketbook (Lampsilis cardium), and fatmucket (Lampsilis siliquoidea) (Unioinidae). Histopathology showed round-to-oval microsporidial spores in the cytoplasm of oocytes in 60% (3/5) of mucket, 100% (4/4) of plain pocketbook and 50% (1/2) of fatmucket. On transmission electron microscopy, mature spores were round to oval, measured 4.13 +/- 0.64 µm (3.14–5.31) long by 2.88 +/-0.37 µm (2.36–3.68) wide. Spores had a thin electron dense exospore with a spiky coat, a thick electron lucent endospore, diplokaryotic nuclei, a polar vacuole, and 27–28 polar filaments arranged in 1 to 3 rows. Sequencing of the small subunit rRNA produced a 1356 bp sequence most similar to Pseudonosema cristatellae, and phylogenetic analysis grouped it with freshwater Neopereziida. The morphologic and ultrastructural characteristics did not match those of Pseudonosema sp. and a new genus and species, Hirsutonosema embarrassi n. gen., n. sp., were designated. Additional studies could evaluate host susceptibility, distribution, seasonality, transmission, and lethal or sub-lethal effects of this parasite to freshwater mussels.

During an epidemiologic survey following a mortality event of freshwater mussels in 2018 in the Embarrass River, Wisconsin, USA, we identified a novel microsporidian parasite in the ovary of mucket (Actinonaias ligamentina), plain pocketbook (Lampsilis cardium), and fatmucket (Lampsilis siliquoidea) (Unioinidae). Histopathology showed round-to-oval microsporidial spores in the cytoplasm of oocytes in 60% (3/5) of mucket, 100% (4/4) of plain pocketbook and 50% (1/2) of fatmucket. On transmission electron microscopy, mature spores were round to oval, measured 4.13 +/- 0.64 µm (3.14–5.31) long by 2.88 +/-0.37 µm (2.36–3.68) wide. Spores had a thin electron dense exospore with a spiky coat, a thick electron lucent endospore, diplokaryotic nuclei, a polar vacuole, and 27–28 polar filaments arranged in 1 to 3 rows. Sequencing of the small subunit rRNA produced a 1356 bp sequence most similar to Pseudonosema cristatellae, and phylogenetic analysis grouped it with freshwater Neopereziida. The morphologic and ultrastructural characteristics did not match those of Pseudonosema sp. and a new genus and species, Hirsutonosema embarrassi n. gen., n. sp., were designated. Additional studies could evaluate host susceptibility, distribution, seasonality, transmission, and lethal or sub-lethal effects of this parasite to freshwater mussels.

The project is located at Carpinteria Salt Marsh, part of the University of California Reserve System. The marsh is located at 34.40°N, 119.53°W, which is near the city of Carpinteria, CA. The "exp_recruitment" data set includes information on site name (site), latitude (lat) and longitude (long) of each site, cage number (cage), the number of egg-transmitted (egginf) and miracidium-transmitted (mirainf) trematode infections per cage, the biomass of snails within a cage (cagebmdens), and the influence (g^3/4) of final hosts that carry egg-transmitted (eggfhi) and miracidium-transmitted (mirafhi) trematodes. The "exp_risk" data set includes information on site name (site), latitude (lat) and longitude (long) of each site, cage number (cage), the length of each snail (length), the mass of each snail (mass), whether the snail was infected with an egg-transmitted trematode (egginf) or miracidium-transmitted trematode (mirainf), the biomass of snails within a cage (cagebmdens), the biomass of snails in the surrounding area (surrbmdens), and the influence (g^3/4) of final hosts that carry egg-transmitted (eggfhi) and miracidium-transmitted (mirafhi) trematodes. These data support the following publication entitled “Host density increases parasite recruitment but decreases host risk in a snail-trematode system” by J.C. Buck, R.F. Hechinger, A.C. Wood, T.E. Stewart, A.M. Kuris, and K.D. Lafferty http://dx.doi.org/10.1002/ecy.1905.

The project is located at Carpinteria Salt Marsh, part of the University of California Reserve System. The marsh is located at 34.40°N, 119.53°W, which is near the city of Carpinteria, CA. The "exp_recruitment" data set includes information on site name (site), latitude (lat) and longitude (long) of each site, cage number (cage), the number of egg-transmitted (egginf) and miracidium-transmitted (mirainf) trematode infections per cage, the biomass of snails within a cage (cagebmdens), and the influence (g^3/4) of final hosts that carry egg-transmitted (eggfhi) and miracidium-transmitted (mirafhi) trematodes. The "exp_risk" data set includes information on site name (site), latitude (lat) and longitude (long) of each site, cage number (cage), the length of each snail (length), the mass of each snail (mass), whether the snail was infected with an egg-transmitted trematode (egginf) or miracidium-transmitted trematode (mirainf), the biomass of snails within a cage (cagebmdens), the biomass of snails in the surrounding area (surrbmdens), and the influence (g^3/4) of final hosts that carry egg-transmitted (eggfhi) and miracidium-transmitted (mirafhi) trematodes. These data support the following publication entitled “Host density increases parasite recruitment but decreases host risk in a snail-trematode system” by J.C. Buck, R.F. Hechinger, A.C. Wood, T.E. Stewart, A.M. Kuris, and K.D. Lafferty http://dx.doi.org/10.1002/ecy.1905.

Quagga (Dreissena rostriformis bugensis) and Zebra (Dreissena polymorpha) mussels are highly invasive and easily transported from one waterybody to another. California has an extensive program designed to prevent the spread of these mussels. This program is coordinated by the California Department of Fish and Wildlife (CDFW) Invasive Species Program, within the Habitat Conservation Planning Branch. This data set summarizes the locations of Quagga and Zebra mussel findings within California waterbodies, using data from the U.S. Geological Surveys NAS (Nonindigenous Aquatic Species) database.

This dataset uses the ITIS recommended Ortmanniana pectorosa, Conrad, 1834 in place of Actinonaias pectorosa, which was used in the Richard et al. 2020 manuscript. Biologists monitoring freshwater mussel (Order Unionida) populations rely on behavioral, often subjective, symptoms to identify “sick” or stressed animals, such as gaping valves and slow response to probing and lack clinical indicators to support a diagnosis. As part of a multi-year study to investigate causes of reoccurring mortality of pheasantshell (Ortmanniana pectorosa, Conrad 1834) in the Clinch River, Virginia and Tennessee, USA, we analyzed the hemolymph metabolome of a subset of mussels from the 2018 sampling period. Mussels at the mortality sites were diagnosed as affected (case) or unaffected (control) based on behavioral and physical signs. Hemolymph was collected in the field by nonlethal methods from the anterior adductor muscle for analysis. We used ultra-high-performance liquid chromatography, quadrupole time-of-flight mass spectroscopy (UHPLC-QTOF-MS) to detect targeted and untargeted metabolites in hemolymph and compared metabolomic profiles by field diagnosis. This dataset contains information about the viral load measured previously by Richard et al. 2020. We also include the intensity of mass spectrum signals from metabololites found in the hemolymph of pheasantshell mussels (Ortmanniana pectorosa, Conrad, 1834). These values are unitless values as the intensity is measured as the area under the curve for each metabolite.

This dataset uses the ITIS recommended Ortmanniana pectorosa, Conrad, 1834 in place of Actinonaias pectorosa, which was used in the Richard et al. 2020 manuscript. Biologists monitoring freshwater mussel (Order Unionida) populations rely on behavioral, often subjective, symptoms to identify “sick” or stressed animals, such as gaping valves and slow response to probing and lack clinical indicators to support a diagnosis. As part of a multi-year study to investigate causes of reoccurring mortality of pheasantshell (Ortmanniana pectorosa, Conrad 1834) in the Clinch River, Virginia and Tennessee, USA, we analyzed the hemolymph metabolome of a subset of mussels from the 2018 sampling period. Mussels at the mortality sites were diagnosed as affected (case) or unaffected (control) based on behavioral and physical signs. Hemolymph was collected in the field by nonlethal methods from the anterior adductor muscle for analysis. We used ultra-high-performance liquid chromatography, quadrupole time-of-flight mass spectroscopy (UHPLC-QTOF-MS) to detect targeted and untargeted metabolites in hemolymph and compared metabolomic profiles by field diagnosis. This dataset contains information about the viral load measured previously by Richard et al. 2020. We also include the intensity of mass spectrum signals from metabololites found in the hemolymph of pheasantshell mussels (Ortmanniana pectorosa, Conrad, 1834). These values are unitless values as the intensity is measured as the area under the curve for each metabolite.

There is a fundamental knowledge gap on the distribution, prevalence, intensity, and ecology of salmonid myxozoan parasites in the Lake Sammamish watershed, Washington. To address this knowledge gap, we tested water samples for Ceratonova shasta, Parvicapsula minibicornis and Tetracapsuloides bryosalmonae DNA from 84 sites distributed throughout the Lake Sammamish watershed in fall 2019 and 74 sites in spring 2020. Our surveillance identified zones with high waterborne parasite loads and provides a proof of concept for this approach that could be expanded throughout the larger Lake Washington watershed.

There is a fundamental knowledge gap on the distribution, prevalence, intensity, and ecology of salmonid myxozoan parasites in the Lake Sammamish watershed, Washington. To address this knowledge gap, we tested water samples for Ceratonova shasta, Parvicapsula minibicornis and Tetracapsuloides bryosalmonae DNA from 84 sites distributed throughout the Lake Sammamish watershed in fall 2019 and 74 sites in spring 2020. Our surveillance identified zones with high waterborne parasite loads and provides a proof of concept for this approach that could be expanded throughout the larger Lake Washington watershed.