Willamette Riverkeeper Continues Survey of Freshwater Mussels To Understand More About River Health

Aug 3, 2018

The western pearlshell mussel is common in the Willamette River. It's red and ridged shell are defining features of its profile.
Credit (Alec Cowan/KLCC)

Freshwater mussel populations are on the decline nationally, and little is known about why. KLCC’s Alec Cowan went downriver to bring us this report on an environmental study in Eugene trying to find some answers.

The process can feel like a treasure hunt.

[CANOE CLANKS]

You take a canoe down the river.

[PADDLE SOUNDS]

Trudge through feet of water, digging down into the river bed.

[SPLASHING]

Hoping to strike gold.

Travis Williams is the executive director of Willamette Riverkeeper.
Credit (Alec Cowan/KLCC)

Mussels, the small hard-shelled mollusks, are an important part of the Willamette River. And that’s why they’re the subject of a two year project from Willamette Riverkeeper. Executive Director Travis Williams:

"What we’re trying to accomplish here is to show that there’s this amazing species of animal that lives in the bottom of the Willamette, that can be over 100 years old. When you say that to most people their eyes kind of light up like, 'What are you talking about?'"

Eugene’s mussel bed was the largest found in a 100-mile survey last year. The most prevalent mussel is called the western pearlshell, which has a deep red shell and – like its name implies – a pearl white interior.

Jessie Rohrig is a volunteer and eighth grade science teacher in Hillsboro.

"...And I like participating in the science because it’s something I can bring back to my students."

She’s volunteered for several years, but this is one of the first times she’s looking for mussels. She’s assisting a diver with a snorkel...

A diver uses a square PVC-pipe rig to comb for mussels.
Credit (Alec Cowan/KLCC)

[SNORKEL BREATHING]

...who combs through a block of riverbed called a quadrad. They’ll remove the mussel, measure it and return it to the water.

Surveyors can look at mussels through aqua scopes, which go into the river and allow a clearer view of their subjects.
Credit (Alec Cowan/KLCC)

Rohrig says the study is an opportunity for her students to engage with science in their community:

"Their warm-up question one day was, 'what data should Willamette Riverkeeper collect on these mussels?' And my students had all kinds of things they wanted to say, so it was really neat."

With little knowledge on why populations are declining nationally, the organization is hoping their surveys can shed some light on changes in mussel health. Williams says the creatures are a unique angle for questioning how environmental factors such as pesticides and urban development can affect river stability.

"To the average person I think what they would wanna know is: are they thriving out here, do we have conditions that work in terms of river health that support this species and enable them to reproduce naturally. From what we’ve seen were beginning to get at those questions, but this study is going to shed more light on that."    

Results of past studies show that mussels in the area are numerous but not reproducing. Initial results this year show that mussels are healthy and cover a wide range of ages. Willamette Riverkeeper expects to publish their results online in early October.