Native freshwater mussels play a critical role in aquatic environments and are considered “ecosystem engineers” and indicators of water quality by constantly filtering water. Populations of native freshwater mussels have declined in recent years, and this decline has been attributed to factors such as habitat degradation, pollution, and invasive species, among others. The importance of these organisms is recognized, and significant efforts are being made by USGS researchers, along with conservation agencies, to conserve and restore the populations of native freshwater mussels. Efforts are being focused on developing sample protocols and diagnostic tools to assess mussel health, developing technology to survey a broad array of aquatic pathogens, and investigating the causes behind the mass mussel die-offs being seen around the U.S.
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Investigation Into Mass Mussel Die-off Events
Principal Investigator – Diane Waller
The decline of native freshwater mussels has been attributed to factors such as habitat degradation, pollution, and invasive species. Although factors such as habitat degradation, pollution, and invasive species have been linked to this decline, these potential causes cannot fully explain the large-scale mussel die-offs that have occurred in the past 20 years. These die-offs have taken place in relatively “healthy” streams across the U.S. and occasionally only one or a few species out of many are affected. Several of these mass mussel mortality events have involved federal and state-listed species. Mass mortality in the Clinch River, Tennessee and Virginia, has been ongoing since 2016 and threatens the U.S. Fish and Wildlife Service’s efforts to restore imperiled species in the Upper Tennessee River Basin. In these and other cases, no cause of the die-off has been identified, despite patterns of spread that suggest a disease process in which an infectious agent or agents may be involved. However, these potential causes cannot fully explain the large-scale mussel die-offs that have occurred in the past 20 years. USGS and partners are investigating underlying causes for the mass mortalities.
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Development of Sampling Protocols and Diagnostic Tools for Assessment of Freshwater Mussel Health
Principal Investigator – Diane Waller
The role of disease in freshwater mussel declines has been largely ignored due to the lack of appropriate diagnostic tools. Furthermore, health assessment of mussels in conjunction with restoration and propagation has not been considered during stocking and augmentation activities. This project will develop standard techniques for nonlethal sampling of freshwater mussels to diagnose disease and assess health condition. The techniques and protocols developed from the project will provide a framework for standardized health monitoring of freshwater mollusk populations in any water body and propagation facility.
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Below are publications associated with this project.
Targeted metabolomics characterizes metabolite occurrence and variability in stable freshwater mussel populations
A bacteriological comparison of the hemolymph from healthy and moribund unionid mussel populations in the upper Midwestern U.S.A. prompts the development of diagnostic assays to detect Yokenella regensburgei
Further bacteriological analysis of annual Pheasantshell (Actinonaias pectorosa) mussel mortality events in the Clinch River (Virginia/Tennessee), USA, reveals a consistent association with Yokenella Regensburgei
Freshwater mussels show elevated viral richness and intensity during a mortality event
A novel gonadotropic microsporidian parasite (Microsporidium clinchi n. sp.) infecting a declining population of pheasantshell mussels (Actinonaias pectorosa) (Unioinidae) from the Clinch River, USA
Mussel mass mortality and the microbiome: Evidence for shifts in the bacterial microbiome of a declining freshwater bivalve
Mass mortality in freshwater mussels (Actinonaias pectorosa) in the Clinch River, USA, linked to a novel densovirus
The status of mussel health assessment and a path forward
A novel picorna-like virus in a Wabash Pigtoe (Fusconaia flava) from the upper Mississippi River, USA
A comparison of bacteria cultured from unionid mussel hemolymph between stable populations in the upper Mississippi River and a mortality event in the Clinch River
Building a response network to investigate potential pathogens associated with unionid mortality events
Below are news stories associated with this project.
- Overview
Native freshwater mussels play a critical role in aquatic environments and are considered “ecosystem engineers” and indicators of water quality by constantly filtering water. Populations of native freshwater mussels have declined in recent years, and this decline has been attributed to factors such as habitat degradation, pollution, and invasive species, among others. The importance of these organisms is recognized, and significant efforts are being made by USGS researchers, along with conservation agencies, to conserve and restore the populations of native freshwater mussels. Efforts are being focused on developing sample protocols and diagnostic tools to assess mussel health, developing technology to survey a broad array of aquatic pathogens, and investigating the causes behind the mass mussel die-offs being seen around the U.S.
Sampling mussels in various states of health to investigate the cause of an acute mortality event in the Embarrass River, Wisconsin. The federally endangered Snuffbox, Epioblasma triquetra, was one of the species affected by the die-off. --------------------------------------------
Investigation Into Mass Mussel Die-off Events
Principal Investigator – Diane Waller
The decline of native freshwater mussels has been attributed to factors such as habitat degradation, pollution, and invasive species. Although factors such as habitat degradation, pollution, and invasive species have been linked to this decline, these potential causes cannot fully explain the large-scale mussel die-offs that have occurred in the past 20 years. These die-offs have taken place in relatively “healthy” streams across the U.S. and occasionally only one or a few species out of many are affected. Several of these mass mussel mortality events have involved federal and state-listed species. Mass mortality in the Clinch River, Tennessee and Virginia, has been ongoing since 2016 and threatens the U.S. Fish and Wildlife Service’s efforts to restore imperiled species in the Upper Tennessee River Basin. In these and other cases, no cause of the die-off has been identified, despite patterns of spread that suggest a disease process in which an infectious agent or agents may be involved. However, these potential causes cannot fully explain the large-scale mussel die-offs that have occurred in the past 20 years. USGS and partners are investigating underlying causes for the mass mortalities.
------------------------------------------
Development of Sampling Protocols and Diagnostic Tools for Assessment of Freshwater Mussel Health
Principal Investigator – Diane Waller
The role of disease in freshwater mussel declines has been largely ignored due to the lack of appropriate diagnostic tools. Furthermore, health assessment of mussels in conjunction with restoration and propagation has not been considered during stocking and augmentation activities. This project will develop standard techniques for nonlethal sampling of freshwater mussels to diagnose disease and assess health condition. The techniques and protocols developed from the project will provide a framework for standardized health monitoring of freshwater mollusk populations in any water body and propagation facility.
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- Publications
Below are publications associated with this project.
Targeted metabolomics characterizes metabolite occurrence and variability in stable freshwater mussel populations
Freshwater mussels (order Unionida) play a key role in freshwater systems as ecosystem engineers and indicators of aquatic ecosystem health. The fauna is globally imperilled due to a diversity of suspected factors; however, causes for many population declines and mortality events remain unconfirmed due partly to limited health assessment tools. Mussel-monitoring activities often rely on populationAuthorsDiane L. Waller, Joel Putnam, John Steiner, Brant Fisher, Grant N. Burcham, John W. Oliver, Stephen B. Smith, Richard A. Erickson, Anne Remek, Nancy BodekerA bacteriological comparison of the hemolymph from healthy and moribund unionid mussel populations in the upper Midwestern U.S.A. prompts the development of diagnostic assays to detect Yokenella regensburgei
Recent bacteriological investigations of freshwater mussel mortality events in the southeastern United States have identified a variety of bacteria and differences in bacterial communities between sick and healthy mussels. In particular, Yokenella regensburgei and Aeromonas spp. have been shown to be associated with moribund mussels, although it remains unclear whether these bacteria are causes orAuthorsEric Leis, Sara Dziki, Isaac Standish, Diane L. Waller, Jordan Richard, Jesse Weinzinger, Cleyo Harris, Susan Knowles, Tony GoldbergFurther bacteriological analysis of annual Pheasantshell (Actinonaias pectorosa) mussel mortality events in the Clinch River (Virginia/Tennessee), USA, reveals a consistent association with Yokenella Regensburgei
Pheasantshell (Actinonaias pectorosa) mussels in the Clinch River (Tennessee/Virginia, USA) have declined dramatically in recent years. The bacterium Yokenella regensburgei was first isolated with high prevalence from Pheasantshells during the peak of a 2017 mortality event, but it was not identified after mortality subsided a few months later. Since 2017, Pheasantshell mortality in the Clinch RivAuthorsEric Leis, Sara Dziki, Jordan Richard, Rose Agbalog, Diane L. Waller, Joel G. Putnam, Susan Knowles, Tony GoldbergFreshwater mussels show elevated viral richness and intensity during a mortality event
Freshwater mussels (Unionida) are among the world’s most imperiled taxa, but the relationship between freshwater mussel mortality events and infectious disease is largely unstudied. We surveyed viromes of a widespread and abundant species (mucket, Actinonaias ligamentina; syn: Ortmanniana ligamentina) experiencing a mortality event of unknown etiology in the Huron River, Michigan, in 2019–2020 andAuthorsJordan Richard, Eric Leis, Christopher D. Dunn, Cleyo Harris, Rose Agbalog, Lewis J. Campbell, Susan Knowles, Diane L. Waller, Joel G. Putnam, Tony GoldbergA novel gonadotropic microsporidian parasite (Microsporidium clinchi n. sp.) infecting a declining population of pheasantshell mussels (Actinonaias pectorosa) (Unioinidae) from the Clinch River, USA
Freshwater mussels of the order Unionida are among the most endangered animal groups globally, but the causes of their population decline 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 tAuthorsSusan Knowles, Eric M. Leis, Jordan C. Richard, Rebecca A. Cole, Rose E. Agbalog, Joel G. Putnam, Tony L. Goldberg, Diane L. WallerMussel mass mortality and the microbiome: Evidence for shifts in the bacterial microbiome of a declining freshwater bivalve
Freshwater mussels (Unionida) are suffering mass mortality events worldwide, but the causes remain enigmatic. Here, we describe an analysis of bacterial loads, community structure, and inferred metabolic pathways in the hemolymph of pheasantshells (Actinonaias pectorosa) from the Clinch River, USA, during a multi-year mass mortality event. Bacterial loads were approximately 2 logs higher in moribuAuthorsJordan Richard, Lewis J. Campbell, Eric Leis, Rose Agbalog, Christopher D. Dunn, Diane L. Waller, Susan Knowles, Joel G. Putnam, Tony GoldbergMass mortality in freshwater mussels (Actinonaias pectorosa) in the Clinch River, USA, linked to a novel densovirus
Freshwater mussels (order Unionida) are among the world’s most biodiverse but imperiled taxa. Recent unionid mass mortality events around the world threaten ecosystem services such as water filtration, nutrient cycling, habitat stabilization, and food web enhancement, but causes have remained elusive. To examine potential infectious causes of these declines, we studied mussels in Clinch River, VirAuthorsJordon Richard, Eric Leis, Christopher D. Dunn, Rose Agbalog, Diane L. Waller, Susan Knowles, Joel G. Putnam, Tony GoldbergThe status of mussel health assessment and a path forward
Declines of freshwater mussel (order Unionida) populations worldwide are attributed to habitat degradation, pollution, and invasive species, among other factors. However, these purported causes do not fully explain the enigmatic decline and large-scale die-offs of mussels that have occurred in assumedly “healthy” streams across a wide geographic region. The roles of the microbiota and pathogens inAuthorsDiane L. Waller, Greg CopeA novel picorna-like virus in a Wabash Pigtoe (Fusconaia flava) from the upper Mississippi River, USA
Unionid mussels are threatened by multiple environmental stressors and have experienced mass mortality events over the last several decades, but the role of infectious disease in unionid health and population declines remains poorly understood. Although several microbial agents have been found in unionids, to date only one virus has been documented—Lea plague virus (Arenaviridae) in propagated TriAuthorsTony Goldberg, Christopher N. Dunn, Eric Leis, Diane L. WallerA comparison of bacteria cultured from unionid mussel hemolymph between stable populations in the upper Mississippi River and a mortality event in the Clinch River
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 those from mussel populations experiencing a mortalityAuthorsEric Leis, Sarah Erickson, Diane L. Waller, Jordan Richard, Tony GoldbergBuilding a response network to investigate potential pathogens associated with unionid mortality events
Unexplained mortality events have confounded the mussel conservation community for over 30 years. While the effects of chemical pollutants and environmental factors have been examined, few investigations have focused on the identification of potential mussel pathogens. Consequently, very little is known regarding the impact that pathogens have on freshwater mussel health, especially as they pertaiAuthorsEric Leis, Diane L. Waller, Susan Knowles, Tony Goldberg, Joel G. Putnam, Jordan Richard, Sarah Erickson, Emilie Blevins, Jesse Weinzinger - News
Below are news stories associated with this project.