By Jamie Bucholz, Ph.D.
PDE’s Freshwater Mussel Technical Manager
Sometimes nature just needs a little push.
The Philadelphia Water Department (PWD) and Partnership for the Delaware Estuary (PDE) are doing exactly that by coaxing a new generation of freshwater mussels into the world. They’ve been doing this by inoculating fish with baby freshwater mussels. Why? To increase the native mussel population in the Delaware River Watershed so they can continue to do what they do best: filter water.
PWD scientists recently collected and brought mussel broodstock back to a demonstration lab at the Fairmount Water Works Interpretive Center in Philadelphia. Once the mother mussels released the baby mussels (called glochidia), scientists from PWD and PDE inoculated fish by putting them in water that contains glochidia and letting those glochidia attach to the fish’s gills. This process of glochidia attaching to fish gills happens regularly in nature but doing it in the lab helps things along.
Freshwater mussels are often known as nature’s water filters. Besides filtering water (an individual adult freshwater mussel can filter up to 10 gallons of water per day), they perform numerous other ecosystem services such as cycling important nutrients and providing habitat for fish species, including sport fish. Yet, freshwater mussels are among the most threatened freshwater animal groups worldwide. Their declines may be partially due to their reliance on fish hosts for their unique life cycles. To reproduce, mussels wait until their fish hosts are nearby, and then release their babies, which then embed themselves into the fish’s gills. The baby mussels will live on the gills for weeks. When they’re large enough to survive on their own, they drop off and repeat this life cycle.
