Biologists in Yellowstone National Park are on the alert for a new ecosystem threat: mussels.
Earlier this year, according to the Bozeman Daily Chronicle, officials in the Montana Fish, Wildlife and Parks confirmed the presence of mussels in Tiber Reservoir—north of Great Falls—and have potentially found traces in Canyon Ferry Reservoir, downstream of Nelson Reservoir in the Milk River, and in the Missouri River near York’s Island fishing access outside of Townsend.
Yellowstone spokeswoman Anna Boykin told the Chronicle no mussels have been found within the Park, but reported that biologists “believe they are moving toward Yellowstone.” From the Chronicle:
Invasive mussels were first discovered in the United States in the 1980s in the Great Lakes, and they have been spreading west since then. The discovery at Tiber was the first time mussels were found in waters in Montana and the Northwest, raising concerns that the organisms might be spread farther than is currently known.
FWP has restricted boating and the removal of docks at Tiber and Canyon Ferry, and a response team staffed by FWP and the Department of Natural Resources and Conservation has been working on controlling and containing the spread and sampling and monitoring waterbodies.
Eileen Ryce, the fisheries division administrator for FWP, told the Montana Fish and Wildlife Commission on Thursday that they have finished analyzing their high priority samples — samples that came from waterbodies connected to Tiber or Canyon Ferry — and that they hope to have all of their lower priority samples finished within the next few weeks. Ryce said no new samples have tested positive for the organisms.
Mussels stick to boat propellers and irrigation and hydroelectric infrastructure and can cause thousands of dollars in damage. Their feeding process can alter water quality and their shells litter shorelines.
“People have been working really, really hard to keep them out of the West,” said Leah Elwell, a program director for the Aquatic Invasive Species Action Network. “We don’t want to have this just going through all of our water infrastructure, don’t want it changing the shorelines of our nice lakes.”
Elwell added that mussel growth can be inhibited by a lack of calcium in a waterbody. Lower calcium makes it harder for mussels to grow their shells. Others have pointed out that mussels have a harder time proliferating in fast-moving streams and rivers—although a place like Yellowstone Lake is ideal habitat.
As mentioned, mussels are also spread by boats. Yellowstone policy permits some private watercraft in the Park, but mandates that boaters obtain a permit and have a park ranger inspect the craft. If a ranger suspects the craft is harboring mussels (or some other invasive species) the craft “will be subject to non-chemical decontamination treatment.”