How Genetics Can Save Endangered Mussels

A piece of the restoration puzzle to save populations of endangered freshwater mussels may have been found, according to a recent U.S. Geological Survey led study. Local population losses in a river may not result in irreversible loss of mussel species; other mussels from within the same river could be used as sources to restore declining populations.
Though they serve a critical role in rivers and streams, freshwater mussels are threatened by habitat degradation such as dams, alteration to river channels, pollution and invasive species. Mussels filter the water and provide habitat and food for algae, macroinvertebrates, and even fish, which are necessary components of aquatic food webs.

“Few people realize the important role that mussels play in the ecosystem," said USGS research biologist Heather Galbraith, lead author of the study.  "Streams and rivers with healthy mussel populations tend to have relatively good water quality which is good for the fish and insects that also inhabit those systems."
Mussels in general are poorly understood and difficult to study. Because of this lack of knowledge, population genetics has become a useful tool for understanding their ecology and guiding their restoration.
More than 200 of the nearly 300 North American freshwater mussel species are imperiled, with rapidly dwindling populations.  Researchers are providing information to resource managers, who are working to reverse this trend.  USGS led research suggests that re-introducing mussels within the same river could reverse population declines without affecting the current genetic makeup of the population.
The research shows that patterns in the genetic makeup of a population occurs within individual rivers for freshwater mussels; and that in the study area, mussels from the same river could be used for restoration.
“That genetic structuring is occurring within individual rivers is good news, because it may be a means of protecting rare, threatened and endangered species from impending extinction,” said Galbraith.  “Knowing the genetic structure of a freshwater mussel population is necessary for restoring declining populations to prevent factors such as inbreeding, high mutation rates and low survivorship.”
Knowing that mussels in the same river are similar genetically opens up opportunities for augmenting declining populations or re-introducing mussels into locations where they were historically found. The genetics also highlight the importance of not mixing populations among rivers without additional studies to verify the genetic compatibility of mussels within those rivers.