Millions of Mussels Thrive in French Creek

French Creek is considered the most ecologically diverse waterway in Pennsylvania and has one of the richest caches of mussels in the Northeast. Although one biologist has called French Creek a happy accident, maintaining its pristine quality takes a carefully planned effort. Here's The Allegheny Front's Deborah Weisberg with the story.

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OPEN: French Creek is considered the most ecologically diverse waterway in Pennsylvania and has one of the richest caches of mussels in the Northeast. Although one biologist has called French Creek a happy accident, maintaining its pristine quality takes a carefully planned effort. Here's The Allegheny Front's Deborah Weisberg with the story.

Weisberg: Itís a drizzly fall morning and French Creek is running a little low. That makes it extra easy to wade the fast-moving water in a section called Venango Riffle. When you look down, you see millions of rocks, and millions of mussels. At first glance, itís hard to tell the difference, until you see a mussel up close. Darran Crabtree is a biologist with the Nature Conservancy, working out of Meadville. He holds in his hand a Rabbitsfoot mussel.

Crabtree: It's never in high abundance in any given place but it's well distributed throughout French Creek

Weisberg: The same is true of other mussels found in French Creek, 28 species in all, including 13 rare kinds of mussels, which also live here in big numbers. Crabtree says it,s a testament to the exceptional health of the waterway.

Crabtree: In French Creek, there are millions of mussels, so we're really blessed. In other creeks, that was probably the case a long time ago, but unfortunately a lot of other rivers and streams have lost their biomassÖa lot of species of mussels.

Weisberg: What makes French Creek special, Crabtree says, is that no one land use, no industry, mining, or road crop agriculture, has dominated the 330-thousand acre watershed south of Erie.

Crabtree: All of that combined has produced a happy accident for French Creek. It doesn't have the industryÖdoesn't have the road crop agricultureÖand another saving grace is it doesn't have the coal, the acid mine drainage. French Creek just survived that. The challenge is to take that happy accident of the past and perpetuate it into the future. That's the challenge of everyone who lives here and conservation organizations both international and local.

Weisberg: The French Creek Valley Conservancy and other organizations are seeking conservation easements from hundreds of landowners along French Creek and its ten major tributaries. They're educating property owners about the importance of creating vegetated buffers along the stream to strain out pollution before it reaches the water. The buffers also help preserve groundwater in the floodplain. Tim Hecie runs the French Creek Valley Conservancy.

Hecie: The people we're dealing with are willing partners, not to set aside and use it but to protect the land, by protecting the land, they're protecting the stream.

Weisberg: In addition to the 28 mussel species on French Creek, there are up to 100 different fish, from darters to walleyes to muskelunge. But Crabtree says mussels are the workhorses, and the unsung heroes, of French Creek.

Crabtree: These animals do a lot of things we take for granted. They're food sources for muskrats. The juveniles are food for benthic fishe, filtering water, doing things we don't think about, and they provide a service to rivers by cleaning them.

Weisberg: Mussels are continuously filtering the entire volume of the 117-mile creek that starts in western New York and joins the Allegheny River in Franklin. Mussels siphon off nutrients they need to survive. They also separate particles from urban and agricultural runoff, coat them with mucous, and deposit them in the streambed.

Crabtree: When you have a healthy bed of mussels you often see so many other creatures attached to them. Just about any rock you pick up is going to have cemented little gravel and other things attached and those are cemented on there via the silk of Caddisflies which often have a green body. These animals are creating a home with the silk. When water flows into this contraption of rock and silk they have a little catch net inside there and they're also filtering particles out of the water. Many things live on shells besides algae. What we have here is a Caddisfly. It will attach to a mussel shell near the siphon because it increases the concentration of food particles right there and that's something Caddisflies can benefit from also.

Weisberg: Although every mussel has a foot it can extend to escape danger, in good habitat mussels tend to stay in place, some for up to a century. But they have unique ways of expanding their range. Crabtree explains how mussels fool fish into becoming hosts for their larvae.

Crabtree: The mussels use a mantle lure which is part of their living tissue to attract fish over and then the fish nibbles at the living tissue on the mussel and the mussel releases packets of larvae into the fishís mouth and the larvae then attach to the fish's gills and a few weeks or months later the mussels drop off the fish. It mimics a bait fish so that a larger fish may be enticed into biting it.

Weisberg: Although mussels are still going through this reproductive ritual in recent weeksÖas water temperatures drop mussels will burrow deeper into the riverbed and essentially go into a long winter sleep.

For the Allegheny Front, Iím Deborah Weisberg.