Recent Rock Snot sitings?

[bill2penn]

Hi,
I'm interested to hear if anyone has seen any rock snot (Didymospheria geminata) recently, and if so where and on what streams/rivers? I'm a flyfisherman but also a microscope enthusiast who likes to view diatoms. Didymo is one of the coolest to view and I'd like to collect some for my microscope viewing. I know that the upper Delaware has had rock snot blooms. The last reported one I could find was in 2012. I'm curious if anyone has seen any since?

Thanks!

Bill

 

[troutbert]

I'm not sure if it's rock snot or not, but recently I saw some sort of pale, slimy stuff in the outflow channel of the Tylersville hatchery (Clinton County).

 

[sixfootfenwick]

Doesn't spring creek and slippery rock both have this?

 

[dryflyguy]

Doesn't spring creek and slippery rock both have this?

Spring creek has mud snails.
Haven't heard anything about didymo there.

Know nothing about either being in SR.

To the OP -
Didymo seems to be a tailwater thing.
Been reported in Delaware and Yough rivers.
A few more rivers in MD too

 

[sixfootfenwick]

Invasive 'rock snot' algae found in Pennsylvania creek

A Pennsylvania creek has a “rock snot” problem. The invasive algae didymo, also known as “rock snot,” was recently discovered in the state.

www.yorkdispatch.com

Here is one.

 

[redietz]

Invasive 'rock snot' algae found in Pennsylvania creek

A Pennsylvania creek has a “rock snot” problem. The invasive algae didymo, also known as “rock snot,” was recently discovered in the state.

www.yorkdispatch.com

Here is one.

Just because a stream has didymo doesn't mean there's bloom year round or in all parts of the stream. Gunpowder Falls in Maryland, for example usually has a very heavy bloom from about late February through early April, then is mostly clear of the stuff until the next. Some years, the bloom doesn't happen at all. The bloom is heaviest nearest Prettyboy dam and tapers off the further downstream you go.

 

[sandflyx]

Lower pine around slate has some

 

[dryflyguy]

Lower pine around slate has some

First I heard about that.
Just in the one area?

I seem to recall reading about a dam on Pine Creek in Galeton.
But guessing it's not high enough to provide any kind of tailwater effect

 

[sixfootfenwick]

Just because a stream has didymo doesn't mean there's bloom year round or in all parts of the stream. Gunpowder Falls in Maryland, for example usually has a very heavy bloom from about late February through early April, then is mostly clear of the stuff until the next. Some years, the bloom doesn't happen at all. The bloom is heaviest nearest Prettyboy dam and tapers off the further downstream you go.

🤷
I hope I didn't say that it did.

Yes, forgot about Gunpowder. There is another.
Pending on where the OP is from in PA and using this timeline, you might find what you are looking for fairly easily.
If it isn't in bloom, you can get a decent day fishing out of it too.

 

[redietz]

I hope I didn't say that it did.

No, you didn't. OTOH, if the OP has to ask where to find it, he may not be familiar enough to know that.

 

[silverfox]

Hi,
I'm interested to hear if anyone has seen any rock snot (Didymospheria geminata) recently, and if so where and on what streams/rivers? I'm a flyfisherman but also a microscope enthusiast who likes to view diatoms. Didymo is one of the coolest to view and I'd like to collect some for my microscope viewing. I know that the upper Delaware has had rock snot blooms. The last reported one I could find was in 2012. I'm curious if anyone has seen any since?

Thanks!

Bill

There's a little bit hanging on just below the tailrace at Jennings Randolph in western MD, just below the upper wire/no trespassing signs. At least there was some last year up there. It used to be worse years ago but hasn't been throughout the lower river (that I've noticed) since then.

 

[bill2penn]

Thanks for the replies. I live near Philadelphia and our water is too warm and/or too rich in phosphorus for didymo to thrive and bloom around here. It likes cold, low phosphorus waters. Most of the Delaware River above Easton has been reported to have at least some didymo blooms in early Spring so I will probably hit that. Gunpowder is another option (which I didn't know about, so thanks for that) but I don't have a Maryland license so I wouldn't be fishing it.
If anyone has any more recent information about blooms, please post about it.
Thanks
Bill

 

[KeviR]

I'm not sure if it's rock snot or not, but recently I saw some sort of pale, slimy stuff in the outflow channel of the Tylersville hatchery (Clinton County).

TB, if it's slimy- it's not didymo. Didymo is kind of cottony and rough to the touch, in spite of how it looks.

 

[PennKev]

Doesn't spring creek and slippery rock both have this?

I'd be shocked to find it in SRC, didymo is associated with cold water and SRC is bathwater in the summer. You may be thinking of the green filamentsous algae which cam get very thick in low and clear conditions.

 

[bill2penn]

It just so happens that we are visiting family in Maryland starting today for several days. So I will have the opportunity to head to Gunpowder Falls and the Prettyboy dam and do some scouting/collecting/picture taking. If you see someone without a fish pole with waders, then it's me!

 

[bdhoover77]

It just so happens that we are visiting family in Maryland starting today for several days. So I will have the opportunity to head to Gunpowder Falls and the Prettyboy dam and do some scouting/collecting/picture taking. If you see someone without a fish pole with waders, then it's me!

It should be a decent day out there — warmer with cloud cover. Please let us know if you see any insect activity.

 

[bill2penn]

So I just got back from my trip to Gunpowder Falls in search of rock snot. I thank @redietz since I found just what he described. The rock snot was most prevalent near the dam. I include one image which is not great but it does show the white tails of some rock snot very near Prettyboy dam. It was some hike to get there from the parking lot near the bridge on Falls Road but worth it. I saw 4 fisherman but none were having any luck. I saw no insect activity but one fisherman in the parking lot told me he saw some fish rising for midges. It's a beautiful stretch of water and makes me think I might have to splurg for a Maryland non-resident license and try it.
But again, many thanks to @redietz for the wonderful directions.
It will take me until next week to process the sample once I return home. I will post some microscope images then.

Bill

 

[dryflyguy]

Are the white tails typical of rock snot?

 

[sixfootfenwick]

Very cool.
I look forward to it. Once again the knowledge of this board comes through.

 

[bill2penn]

Are the white tails typical of rock snot?

Yes the white toilet paper kind of tails are characteristic of the bloom form of didymo.