Assessing Impacts of Emerging and Established Diseases to Aquatic Ecosystems

Science Center Objects

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.

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.

(Credit: Diane Waller, Upper Midwest Environmental Sciences Center. Public domain.)

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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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Development of a Broad Microarray Technology to Survey for Aquatic Pathogens

Principal Investigator – Diane Waller

The need to maintain healthy aquatic ecosystems and sustain healthy communities is greatly recognized. Aquatic pathogens pose a threat to many organisms, and being able to identify and test for an array of aquatic pathogens is important in understanding the overall health of an aquatic system. A DNA microarray tool will be developed for detection of a broad suite of aquatic pathogens (fish, amphibian, mussel) that are indicative of ecosystem health. This tool will allow for whole aquatic systems to be tested for the presence or absence of many aquatic pathogens, allowing for management decisions to be more informed.