Conservation and Restoration of Native Freshwater Mussels

Science Center Objects

Freshwater mussels are the most imperiled group of animals in North America, with 66% of species at risk. Mussel populations are declining globally, but the factors contributing to these declines are largely unknown. Habitat fragmentation and alteration, point- and non-point source pollution, navigation-related impacts, and exotic species introductions are thought to be responsible for mussel declines in many systems. USGS researchers work with conservation agencies and organizations to conserve and restore mussel populations. Current efforts are centered around quantifying the ecosystem services that native mussels provide, examining the sub-lethal effects of lampricides on native mussels, predicting the distribution and abundance of mussels from geomorphic indices, and developing methods to assess the relative health of mussels in the Upper Mississippi River.

Ecosystem Services Provided by Native Freshwater Mussels

Principal Investigator – Teresa Newton

Through filter-feeding, native mussels may improve water quality

Through filter-feeding, native mussels may improve water quality

(Credit: Tim Lane. Public domain.)

Clean water is vital to public health, commerce, and recreation in the United States. Despite great efforts to reduce water pollution, many waters in the U.S. remain impaired. Having clean water not only supports considerable economic activity, but it also costs billions annually to maintain and provide. Freshwater mussels are avid filter feeders, and remove algae, sediment, nutrients, harmful bacteria, and metals from rivers and lakes. Because of this, mussels have been described as the “livers of our rivers”. This filter feeding activity is one of several ecological services that mussels provide to our lakes and rivers. However, the global declines in mussel populations may result in fewer ecological services being performed by mussels. Restoring native freshwater mussels to the nation’s rivers and streams is of growing interest to non-governmental organizations and Federal, state, and local management agencies as a potential strategy for improving water quality and aquatic ecosystem health. This pilot project seeks to quantify both the monetary and non-monetary benefits provided by native mussels in one reach of the Upper Mississippi River. 

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Exposure of mussels to lampricides often has a narcotizing effect, including extending their foot for long periods of time.

Exposure of mussels to lampricides often has a narcotizing effect, including extending their foot for long periods of time.

(Credit: Teresa Newton, USGS-Upper Midwest Environmental Sciences Center. Public domain.)

Potential reproductive effects of the lampricides TFM and TFM:1% Niclosamide on native freshwater mussels

Principal Investigator – Teresa Newton

There has been growing concern by Federal and State agencies in recent years over the risk that lampricide applications may have on non-target organisms. Due to their highly imperiled status, sedentary behavior, and bottom dwelling nature, native freshwater mussels are a group of organisms that may be adversely affected by lampricides. Several aquatic contaminants have been shown to cause a premature release of larvae (glochidia) from female mussels. If these larvae are released before they mature, there may be corresponding adverse effects on the recruitment of juvenile mussels into the population. USGS scientists are exploring the potential for lampricides to adversely affect reproduction in native mussels.

 

 

 

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Map of Navigation Pool 8 of the Upper Mississippi River showing areas predicted to have high mussel densities (red) based on geo

Map of Navigation Pool 8 of the Upper Mississippi River showing areas predicted to have high mussel densities (red) based on geomorphic conditions.

(Credit: Steve Zigler, USGS-Upper Midwest Environmental Sciences Center. Public domain.)

Systematic Analysis of Hydrogeomorphic Influences on Native Freshwater Mussels

Principal Investigator – Teresa Newton

Over the past 50 years, about 20 native freshwater mussel species have been lost or greatly diminished from the Upper Mississippi River System and overall abundance of mussels has substantially declined in many portions of the river. While factors contributing to these declines are largely unknown, native mussels appear to be responsive to variation in hydrophysical and geomorphic features. Federal and state resource managers are interested in understanding the physical, hydraulic, and geomorphic factors that might drive the distribution and abundance of freshwater mussels. A better understanding of the geomorphic metrics that associate with dense and diverse mussel assemblages can guide the designs of future habitat rehabilitation enhancement projects to support and provide new and improved habitats for mussel assemblages.

 

 

 

 

 

 

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Scientists remove a sample of hemolymph from a threeridge mussel to better understand a mussels’ microbiome

Scientists remove a sample of hemolymph from a threeridge mussel to better understand a mussels’ microbiome.

(Credit: Teresa Newton, USGS-Upper Midwest Environmental Sciences Center. Public domain.)

Characterization of the Mussel Microbiome: Assessment of Microbe Biodiversity Across Species, Individuals, and Environmental Compartments

Principal Investigator – Teresa Newton

There has been substantial research on mussels in many areas, however, methods to evaluate the overall health of mussels has received less attention. Assessing mussel health is difficult due to the lack of established benchmarks by which to judge what is suitable or normal. A mussels’ body is full of bacteria, viruses, and fungi that are collectively known as the microbiome. Understanding the mussel microbiome may inform why some efforts to restore mussel communities fail while others succeed. The development of non-lethal diagnostic tools to assess mussel health prior to restoration may avoid harming existing populations and may minimize risks to existing populations and habitats. This study will explore the biodiversity of the mussel microbiome—among species and tissues—within a presumably healthy mussel assemblage in the Upper Mississippi River. This will provide baseline information on mussel health that can be used to assist in propagation and restoration efforts.