By the CUJ
MISSION – Research conducted by the Confederated Tribes of the Umatilla Indian Reservation has led to the
discovery that some freshwater mussels in the Western United States are genetically different and may
actually be a separate genus.
A research paper entitled “Three Deeply Divided Lineages of the Freshwater Mussel Genus Anodonta in Western
North America” was recently published in a scientic journal called Conservation Genetics. Authors included Jayne
Brim-Box, a biologist working on the Tribes’ Freshwater Mussel Research and Restoation Project, and David Wolf,
a mussel technician in the Tribes’ Fisheries Program. Another CTUIR employee, Donna Nez, a fisheries technician,
provided feld assistance during the research. Additionally, David Close, a fisheries biologist, and Gary James,
manager of the CTUIR Fisheries Program, were instrumental in establishing the Project. “This knowledge is a big
step forward in understanding these mussels and how best to manage and restore them to our waterways,” said
Karen Mock, the Utah State University professor who led the research work. “Scientifically, it is big news that will
impact many states in the western U.S. and how they manage mussels.”
Freshwater mussels are a native component of North American aquatic ecosystems, but little is known about them.
“They have not been well studied, but likely are very important functional members of the ecosystems,” said Mock.
“They also have cultural value as one of the ‘first foods.’” Freshwater mussels have declined dramatically over the
last century, probably due to sedimentation, channel modifications, water diversion for agriculture, and losses of
host fish, Mock said.
Mock said researchers don’t know much about what mussels eat, what kinds of habitats and fish hosts they require,
and in some cases even what they should be called.
“This makes it very tough to know how their populations are changing, what factors might be contributing to their
decline, how their presence might benefit a stream and other species,” Mock said. Research conducted since 2003
in the Tribes’ Freshwater Mussel Research and Restoration Project has been trying to answer some of those
questions.
“The Umatilla Tribes have taken a keen interest in conserving these animals and has become a national leader in
research on freshwater mussels,” Mock said.
The Project involved sampling of mussel densities at nearly 80 locations in the Umatilla and John Day rivers –
some 36 locations in the Umatilla, 30 in the Middle Fork John Day and more than two dozen others in seven
tributaries – North Fork and South Fork Umatilla rivers, Shimmiehorn, North Fork Meacham, Iskuulpa, Owsley
and Ryan creeks. Surveyors snorkeled, collecting mussels in designated areas for a set amount of time. At each
location, mussels were collected, identified by species, measured for length, and a tiny bit of tissue was sampled
for genetic analysis before the mussels were returned to the river.

Mussels lifcycle includes unique fertilization, attachment to host fish

The life cycle of freshwater mussels is intriguing. Most live burrowed in sand and gravel at the bottom of rivers
and streams. Only a few are adapted to the quiet water and muddy depths of lakes, ponds and reservoirs.
Unlike most animals, which must travel in search of food, their food drifts to them, mainly tiny plants and
animals called plankton suspended in the water. By drawing water inside their shells through a siphon, their gills
filter out food and take in oxygen.
The unusual life cycle for freshwater mussels begins when eggs held inside the female are fertilized by sperm
drawn inside her while siphoning water. For most species, if a male of her kind isn’t nearby upstream, she can’t
reproduce. For a few, this is not a problem because they seem to be able to fertilize themselves.
Once fertilized, the eggs develop into a larval stage inside the female before they are released into the water to
begin a parasitic stage. With little time to waste, the youngsters - called glochidia - must attach themselves to
a host fish or perish.
For some mussels, the host is limited to only a few fish species, which means their status is linked to the health
of certain fish populations. No one knows for sure, but it appears this parasitic stage can last anywhere from 10
days to several months, Brim-Box said. At some point, the larvae transform into young mussels that drop off
the fish to begin a live in the stream bottom.
Mussels do not have eyes, so their methods of attracting host ?sh are even more remarkable. Some species
have modi?ed their mantles into lures resembling ?shes, insects or other food items, which often pulsate in
swimming-like motions, according to G. Thomas Watters, who writes about mussels for Conchologists of America.
Other species have been known to display a fish-like lure played out in the water on a strand of mucus up to
eight feet long.
Threats to the long-term survival of mussels, according to the National Parks Service, includes degradation of
habitat (sediment loading, erosion, pollutants from improper agricultural, forestry and mining practices);
channelization, dredging and bridge construction; traffic (large vessels or domestic animal crossings); dams or
other barriers to fish migration; over harvest and illegal collecting; and competition from non-native species
such as the zebra mussel and Asian clam.
Mussels have important functions in aquatic environments, the National Park Service says.
“They are a link in the food chain and help to maintain water quality. Because they are long-lived and
particularly sensitive to changes in water quality, mussels are important indicators of aquatic ecosystem health.
The disappearance of mussels from a river or lake often signals that other aquatic species are at risk.”