Eugene weekly., November 16, 2017, Page 12, Image 12

VOLUNTEERS ASSESS MUSSEL POPULATIONS IN THE WILLAMETTE RIVER
West. Contrast this to the eastern portion of the U.S. where
270 mussel species are found.
Holding the shell of a Western pearlshell in his hand,
Williams points to the growth rings on the ancient mussel
that show its age, in a way similar to tree rings, if one were
to cut into the shell and analyze it. In Oregon, freshwater
mussels can’t legally be plucked from their beds, and
Riverkeeper had “scientific taking permits” from the
Oregon Department of Fish and Wildlife for the study the
group conducted this past summer.
Williams says when it comes to what’s important about
mussels, it’s first of all “cool that these animals exist,”
and “it is about instant respect just given their potential
lifespans.” Also, he points out, mussels must interface with
all of humanity’s collective actions, like pollution, to stay
alive.
Celeste Mazzacano is an entomologist whose
invertebrate studies led her to a fascination with mussels.
She says the bed along Norwood Island is notable because
it has a sandy bottom but the Western pearlshell mussels
that dominate it tend to like it gravelly, and she’d never
seen an aggregation of mussels that big.
“It was a real wow just to see that many of our native
mussels in one place,” she says.
Mazzacano and her volunteers found lots of live
mussels there, she said, but also lots of shells from dead
mussels. “We know there’s a lot of mussels here,” she says,
“but not much about them.”
Were they only Western pearlshells? Were there any
young mussels?
As it turns out, there were really no young mussels,
and there were some floaters in the channel. In a study
published this fall on the Norwood bed that Mazzacano did
for Willamette Riverkeeper, she noted that 90 percent of
the 40,000 or so mussels in the channel were older, larger
mussels, with only a few younger mussels and no juveniles.
“Some time in the somewhat recent past conditions
were good for mussels, so what’s up here?” she asks.
12
November 16, 2017 • eugeneweekly.com
PHOTOS COURTESY WILLAMETTE RIVERKEEPER
Mazzacano says freshwater mussels in the Willamette,
which she calls a “highly impacted river that gets a lot of
abuse,” haven’t really been studied systematically. And
people who have lived in the area a long time will say,
“I remember when there were a lot more mussels in here.
When I was a kid, they were all over the place.”
That statement alone says something about the
importance of mussels, because mussels aren’t really
something that stands out for many people, even people
who think of themselves as river-lovers.
“They are not the sexiest animal that people take notice
of,” Mazzacano tells me. “But they really are engaging. It’s
like a treasure hunt; they’re kind of cryptic.”
She says she’s picked up a lot of rocks, thinking she
was grabbing a mussel. When she finds one, “It’s a feeling
of discovery.”
The Liver of the River
Emilie Blevins is an endangered species conservation
biologist with the Xerces Society. Like Mazzacano, she
is fascinated by mussels. Butterflies and bumblebees are
beautiful and attractive, she says, but mussels, burrowed
into riverbeds, you don’t see unless you are specifically
looking for them. “They are really interesting creatures
with a really complex life cycle.”
And, she says, these seemingly dull little bivalves
function as “the liver of the river.”
A mussel can remove E. coli, flame-retardants,
pharmaceuticals, pesticides and heavy metals, she says.
It cleans water, makes sunlight penetrate the water more
deeply and helps other organisms like algae grow. Mussels
benefit fish, birds and the river as a whole. She compares
the mussels to a wastewater treatment plant.
If you were to look down — if only the water were clear
enough — you would see a dark blackish-brownish shell
and, beneath that, the mussel’s fleshy foot, holding it to its
bed.
“That animal might have been there for 40 years,”
Blevins says, “filtering water constantly as it’s flowing
over it, giving it the oxygen that it needs, collecting food
and filtering contaminants.”
And that fleshy foot anchoring the mussel down,
keeping it largely in one spot for its lifetime, also helps
stabilize the riverbed.
After the mussels clean the water and extract nutrients,
what is essentially their poop falls to the river bottom
and feeds tiny juvenile invertebrates that become aquatic
insects and other creatures, which then feed fish and birds.
Healthy mussels are a sign of river health, she says, and
when they start to decline, it’s time to become concerned.
Blevins points to another recent mussel study, this
one done by Xerces and the Confederated Tribes of the
Umatilla Indians, showing mussels have been lost from
one out of five watersheds in which they once occurred in
the West.
Xerces and the Umatilla created a database of mussel
records from research and museum collections, historical
publications, and public agency and personal records
going as far back as 1834. The creation of the Western
Freshwater Mussel Database took 10 years. While the
work is impressive, the results are a little discouraging.
Using the criteria for the ICUN (International Union for
Conservation of Nature) Red List of Threatened Species,
the researchers found that the Western ridged mussel and
winged floater are “vulnerable” — they have disappeared
from more than 30 percent of their range, and the Western
pearlshell is gone from more than 15 percent of its range
and is considered “near threatened.”
The U.S. Geological Survey says more than 70 percent
of the continent’s 302 species are extinct or imperiled.
While they are ICUN listed, none of Oregon’s mussels are
federally listed, meaning they don’t get special protections
that could aid in their uncertain future. “In Oregon they are
not protected other than the fact that you cannot harvest
them, and you basically are not supposed to pick them up,”
Williams says.