Didymo found in Maryland

The invasive exotic diatom Didymo Didymosphenia geminata has been found in the Gunpowder River below Prettyboy Reservior.

The invasive exotic diatom Didymo Didymosphenia geminata has been found in the Gunpowder River below Prettyboy Reservior.

Clearly the result of some irresponsible diatom hobbyist.

More seriously though, where does it originate and how did it get there?

hey Smiley,

Didymo is bad stuff, forms thick mats that blanket the stream bottom. It's now widespread in the western US, introduced into New Zealand and South America, and appears to have been largely introduced and dispersed by felt-soled trout fishermen (most new outbreaks are in popular trout fisheries). I'm starting to reconsider my love for felt soles on my boots, but the other alternatives that don't pick up as much debris (best on the market is Patagonia's "stickyrubber") wear out faster and IMO don't grip as well on some substrates (although a combo stickyrubber and carbide studs might be the ticket, they'll be my next pair).

An effective public info campaign to get people disinfecting their waders after EVERY trip (but particularly to foreign destinations) is sorely needed...

Dave

It has also made it's way east of the Mississippi River and is showing up in New England. As Dave said, it shows up, and did in Maryland, in a popular trout stream. We began disinfecting after every time we got into a waterway last year and were promoting that idea to others who work in waters of Maryland. We actually first got pressure to disinfect from TU out of western Maryland. We are ditching felt all together now even though we disinfect all our equipment that comes into contact with water. Don't even get me started on how much of a pain in the ass it is to carry multiple sprayers and have a disenfection station set up at the end of every day. Proactive regulations, white listing, blitzing, I don't even know if that matters anymore...my pesimism is at an all time high. I don't want to even get started on trying to proactive regulate, my blood pressure is high enough.

I did see a nice presentation by biologists at EcoAnalysts did on macroinvert assemblage changes to a stream in Idaho.

The TU chapter in my area was discussing this recently. It got me wondering if didymo is likely to be also spread by other, biological means of transport. Like bird feet. Felt soles do seem to be a problem, if indeed popular trout streams are being infested more so than others. But I also wonder if the other streams are underreported. Disinfection is a good start at prevention, but I have a sinking feeling about this.

Oh man that's bad news. Was it pretty widespread where you guys found it? It sounds like some didymo warning signs need to be put up in the Gunpowder before didymo makes its way out west to some brook trout streams.

Apparently it has dispersed quite a ways downstream of the reservoir already but is in sparse clumps. The area is so heavily used by fisherman and kayakers that drift of broken pieces alone is probably contributing to it's spread downstream. I believe warning signs have gone out already to the area and a press release is finally going out. There was an emergency meeting of the "invasive species matrix team" today. The days of felt sole waders are numbered at DNR and disinfection is across the board. Not sure how far outside of DNR that will stretch. I'm really biting my tounge on everything else other than giving information that I know because I personally feel some far reaching and immediate action needs to be taken rather than a drawn out reactive approach.

Baltimore Sun - Didymo

Balitmore Sun - 5/7