For the first time in nearly 120 years, researchers confirmed the presence of live individuals of the state-endangered salamander mussel in Illinois, marking a major biodiversity milestone for the state.
Conservation biologist Mark Davis and malacologist Sarah Douglass at the Illinois Natural History Survey (INHS), a division of the Prairie Research Institute, combined cutting-edge environmental DNA (eDNA) techniques—analyzing genetic material shed by organisms such as tissue or feces—with conventional mussel surveys to detect both the salamander mussel (Simpsonaias ambigua) and its host, the mudpuppy (Necturus maculosus), in the Sangamon River in central Illinois.
On June 24, 2024, Davis and his team collected water samples along the Sangamon River in Champaign County to test for eDNA. The genetic analyses targeted both the salamander mussel and the mudpuppy, the larval host for the mussel. One of eight sites returned with positive eDNA detections for both species.
Mudpuppies, fully aquatic salamanders, play a crucial role in the salamander mussel’s life cycle. The larvae, called glochidia, attach to the external gills or skin of these salamanders before maturing into free-living adult mussels. In Illinois, mudpuppies are state-threatened, and salamander mussels are candidates for federal endangered status under the U.S. Endangered Species Act.
“Instead of investing weeks or years searching all possible habitats throughout the state, eDNA allows us to focus like a laser on those places where we have genetic traces,” said Davis. “This method allowed us to strategically deploy Sarah’s expertise at the perfect site.”
The salamander mussel is challenging to detect using conventional methods due to its small size—less than two inches long—and its habitat preference. They typically live under stones or slabs in medium to large rivers, according to the Urban Biotic Assessment Program.
On October 2, 2024, Douglass conducted a targeted timed-search mussel survey at the site where eDNA revealed the presence of both species.
“I was ecstatic and doing a happy dance in my head after finding the fresh dead shell. I just knew we’d find live ones, and we did shortly after,” said Douglass. “I also felt a sense of relief to be able to say with certainty that, yes, this species is still alive in Illinois.”
The survey revealed multiple live salamander mussel specimens and several recently deceased individuals (shells). The researchers collected genetic samples from all live individuals and vouchered two specimens for accession into the INHS Mollusk Collection.
The salamander mussel has not been documented alive in Illinois since the early 1900s when Frank C. Baker documented his and other early naturalists’ encounters with this species statewide. According to INHS malacology collection curator Alison Stodola, the species is so rare that the INHS collection contains only 26 records from Illinois—all shells from deceased specimens—with about 30 more from the state held by other institutions worldwide.
The rediscovery may accelerate efforts to protect both the salamander mussel and the mudpuppy. Davis and Douglass expressed hope that the mussel species could soon receive federal protection.
“The salamander mussel is a candidate for endangered listing under the federal Endangered Species Act,” said Davis. “This provides critical data and information to the U.S. Fish and Wildlife Service for not only their decision making but designating critical habitat, including in Illinois.”
Now that the species is confirmed to still exist in Illinois, future studies on the salamander mussel may shed light on its life history or habitat preferences, informing new conservation efforts.
“This find is incredible and it will allow us to help answer a variety of conservation-related questions for these species,” said Douglass. “Statewide sampling efforts using a combination of eDNA and conventional sampling will give us a clearer picture of species’ status and distributions.”
This research is funded by U.S. Fish and Wildlife Service Competitive State Wildlife Grant and sponsored by the Minnesota Department of Natural Resources.
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Media Contacts: Sarah Douglass, sabales@illinois.edu, 217-300-4018; Mark Davis, davis63@illinois.edu