Didymo in Big Pine Creek, Pennsylvania

From an e-mail sent on July 10th by Dr. Mel Zimmerman at Lycoming College in my home town of Williamsport, Pennsylvania:

Attached is a picture we took this morning from a sample above Waterville – coming to a watershed near you.


First record of the invasive diatom Didymosphenia geminata in the Pine Creek watershed, Lycoming County Pennsylvania.

Pennsylvania Department of Environmental Protection (DEP) Biologists have, as a result of routine monitoring, detected the presence of the invasive diatom Didymosphenia geminata, also known as Didymo, in the Pine Creek watershed, Lycoming County PA.  Representative specimens were sent to The Academy of Natural Sciences of Drexel University where Dr. Marina Potapova confirmed DEP’s identification.

Living Didymo diatoms were obtained on June 18, 2013 from Pine Creek at a location upstream of Waterville in the vicinity of the Hamilton Bottom Canoe Access Area; Lycoming County.  This represents the first evidence of this invasive diatom in this watershed.  In fact, prior to this discovery no Didymosphenia geminata diatoms were known by DEP to exist in Pennsylvania waters except at verified infestations sites in the Youghiogheny River and the West Brach / mainstem of the Delaware Rivers. 

All Water Quality professionals (and ALL anglers) should take precautions against spreading Didymo by properly cleaning and disinfecting aquatic gear prior to working in other waters. For more information, please visit PA Fish & Boat Commission website for a fact sheet and further guidance at:


You are encouraged to forward this notice to your Agency co-workers, fellow aquatic biologists and other Water Quality professionals. (and your fishing friends).

Tony Shaw | Water Pollution Biologist IV | Chief, Monitoring Section
Environmental Protection | Point & Non-Point Source Management
Rachel Carson State Office Building
400 Market Street | Harrisburg, PA 17105-8774
Phone: 717.787.5017 | Fax: 717.772.3249

Didymo - aka Rock Snot confirmed in Big Pine Crek,Pennsylvania, above Waterville. This is bad news.

Didymo – aka Rock Snot confirmed in Big Pine Creek, Pennsylvania, above Waterville. This is bad news.

Rock snot can basically take over the stream bottom, when it colonizes an area, there is room for nothing else to live. It can obliterate the environment where invertebrates live by covering it up. When trout spawn, the female clears a redd, but by the time the eggs hatch, if didymo is nearby, it will have recolonized the redd and the fry will be unable to escape. But, by that time, the eggs will have been smothered anyway.

Anglers and everyone using Big Pine Creek are strongly urged to take the necessary precautions to keep this from spreading. However, the pessimist in me, knowing there will be people visiting Pine Creek that are unaware of the presence of didymo, will most likely unknowingly carry it to other streams in the area. Some of the best trout streams in Pennsylvania – Big Fishing Creek, Spring Creek, Penn’s Creek, Slate Run, Little Juniata River, are all at risk. Please be extremely careful. Guess we’re going to have to start carrying Clorox and a bucket or large dishpan in our cars so we can disinfect our wading shoes and the neoprene feet on our waders when we fish different streams in the same day.

6 comments on “Didymo in Big Pine Creek, Pennsylvania

  1. flydressersguild says:

    Invasive species are becoming a real threat to not only our fishing but to all native habitats. In the UK we now have the “killer shrimp” (Dikerogammarus villosus) that not only hitches a lift on anglers nets & waders etc but in water that collects in canoes and small craft which are much less likely to dry out before being transported to new locations.
    Don, I suspect that the Rock Snot problem is going to be equally difficult to deal with, the anglers may happily take precautions but non-anglers who use rivers and streams as playgrounds may be harder to convince 😦

    • Don Bastian says:

      I never heard of killer shrimp, sounds bad. We also have the snake head fish from China. I doubt they are established in Pennsylvania, but they are in Maryland. Supposedly the Chinese immigrants eat them, so they have them in their groceries…but why? Let them eat tuna, for Pete’s sake, when the danger of their release, which has already occurred, is a possibility. There should be a law prohibiting their importation.

      • I saw a documentary about the snakeheads, I understand that they are voracious eaters and feeders, can travel overground and live for several days out of water… I found a news story from the Washington Post in 2002 (http://www.csa.com/discoveryguides/snakehead/news0712.php), the guy responsible needs putting out of his mesery!

      • Don Bastian says:

        Hi Darrell;
        Yes, that’s right. Can you imagine??!! I think they have some in Maryland…not sure where else. Sounds like a prehistoric fish-monster. Good thing they don’t grow to ten feet long! Thanks for posting that link, I’ll have to check it out…

  2. Bob Stanton says:

    You’re right Don, that’s really bad news. That, coupled with the fact that they’ve found the Hemlock Wooly Adelgid and the Emerald Ash Borer here in the Allegheny National Forest has me out of sorts. Oh, and lest I forget, there are zebra mussels in the Allegheny watershed now, too! The only good news I’ve heard lately is the reintroduction, or introduction as it were, of the hybrid chestnut trees. Here’s hoping that they take hold.

    • Don Bastian says:

      Hi Bob;
      Thanks for your comment. There are Wooly Adelgids not two miles from my home along the Bobst Mountain Road. Zebra mussels in the Allegheny watershed, oh no! 😦
      Mankind has certainly messed up the environment with the introduction of all these invasive species…what to do?

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