Dive Team

Helping Freshwater Mussels Clean Up the Delaware River

These mussels help to filter the water by removing sediment, algae and pollutants.

These mussels help to filter the Delaware River by removing sediment, algae and pollutants.

by Steve Donohue

During a recent survey on the Delaware River, I helped collect for scientific research, a freshwater mussel that was likely in the river below me when I was a kid in the 60s driving over a nearby bridge in the backseat of our family’s station wagon. While some species can live to 100 or more, the one I’m holding – and after examining, returned to the water – is probably 50-60 years old and has been silently filtering water all that time.

These freshwater bivalves, like their saltwater relatives, oysters, provide valuable “ecosystems services” by filtering water and removing sediment, algae, and pollutants, while also stabilizing the bottom substrate. According to the Partnership for the Delaware Estuary (PDE), a National Estuary Program  partner, one adult mussel can filter 20 or more gallons of water a day so this one mussel has probably treated several hundred thousand gallons of water over its lifetime.  Multiply that by hundreds or thousands of mussels in a healthy population and the numbers add up quickly.

Not long ago it was believed some species of freshwater mussels were extinct in the Delaware River due to pollution and spills from the River’s industrial past, over-harvesting for bait, loss of forests along streams, loss of fish hosts needed for reproduction, and dams that block fish passage.

In 2007, the PDE launched the Freshwater Mussel Recovery Program (FMRP) to help the comeback of the one dozen native species classified as reduced, threatened, or locally extinct.

EPA’s Scientific Dive Unit is collaborating with PDE, the Academy of Natural Sciences of Drexel University and the Philadelphia Water Department in restoration efforts.  One goal is to determine where freshwater mussels are located, and how many are present.  This will help quantify the current benefit they provide to water quality in the Delaware and the potential benefit a larger, healthy population would provide for future generations.

 

About the author: Steve Donohue has been an environmental scientist at EPA for over 25 years.  He is the Unit Dive Officer on the EPA Mid-Atlantic Scientific Dive Unit and works to address climate change issues and improve the efficiency and sustainability of public and private sector facilities.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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The Art of Underwater Choreography for EPA Scientific Diving

by Sean Sheldrake, EPA Region 10 Dive Team and Alan Humphrey, EPA-Environmental Response Team (ERT)

On the mind of the divers, as well as myself, an EPA divemaster, is always safety first and foremost. To be safe and deliver good science in a zero visibility underwater environment, choreography is key. While the divers don’t “dance” underwater very often, they do a dance of sorts with their equipment. Anchorage, current, wind, and other factors impact how the diver will deploy off the back of the vessel. Any misstep in the diver’s descent could cause lines to be crossed or severed, ruining data quality—and worse yet, could become a danger to the diver. EPA divers practice escape from entanglement problems on a regular basis, but underwater choreography ensures these situations are few and far between. Before I let any of my divers hit the water, they all must show me how each hand and fin will be placed as they deploy. We rehearse steps including exhausting air out of their bulky drysuit in preparation for descent, checking their remaining air gauges for their primary and emergency gas supply, and which hand each sampling instrument will be placed in. If lines are crossed during this “dry” drill, we terminate the exercise and start over. If the diver cannot show me how they can complete their task on the vessel, how can they complete it underwater with added distractions? Once the diver shows me how this can be done successfully on land, their 100 pounds plus of specialized diving equipment for contaminated water is donned. I’ll ask them one more time if they are feeling ok and ready to dive as we run through a predive checklist, much like ones pilots use before a flight. Any hesitation and they’ll be asked to step down without penalty from the day’s dives. Once all systems are go for the diver I will check for large vessels in the area and coordinate with the US Coast Guard as needed. We simply will not start a dive near a shipping lane with any possibility of vessels inbound. I tell the diver to “splash” and immediately we go back to the verbal cues we have rehearsed—“Sampler in the left hand, your communications cable in your right…let me know when you feel the bottom on your fin tips—that’s it, keep taking line downcurrent…you’re on target.”

Read more about the latest in EPA scientific diving at www.facebook.com/EPADivers

About the authors: Sean Sheldrake and Alan Humphrey both serve on the EPA diving safety board, responsible for setting EPA diving policy requirements. In addition, they both work to share contaminated water diving expertise with first responders and others.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.