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Mussel ID please


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#1 Michael Wolfe

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Posted 11 October 2014 - 10:42 AM

This was found today at a stream clean up event (and put back in the water).

We are east of Atlanta on the Yellow River a trib of the Ocmulgee. Can anyone help me tell the folks here what they saw?

I also have an aquarium set up with fish we caught at this event. But I don't know the mussels.Attached File  image.jpg   98.19KB   7 downloads
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#2 Guest_ThomasDodson_*

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Posted 13 October 2014 - 11:57 AM

I'm not familiar with Southern U.S. mussel species but it looks like a species of pigtoe. A google search seems to suggest there are multiple species of pigtoe in Georgia so hopefully somebody more familiar with the area and species will chime in. It seems a little stout to be an Elephant Ear but I would look into that as well.

#3 Guest_Skipjack_*

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Posted 13 October 2014 - 01:07 PM

I will try to get David Cravens to check this out.

#4 Guest_UncleWillie_*

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Posted 13 October 2014 - 01:10 PM

If those are a grown man's hands, the mussel seems a bit large for Georgia elephant ear (Elliptio dariensis)[unless its a huge female]. I'd be putting my money on Southern pondhorn (Uniomerus obesus) instead.

#5 Guest_fundulus_*

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Posted 13 October 2014 - 01:52 PM

Yes, I think UncleWillie has it, my first thought was elephant ear but it wasn't quite right. And I couldn't think, "pondhorn"...

#6 Michael Wolfe

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Posted 13 October 2014 - 02:12 PM

Thanks guys. It was not an adult's hands. But still was a big critter. So I will go with Southern Pondhorn.
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#7 Guest_dac343_*

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Posted 13 October 2014 - 03:45 PM

Our opinion is dariensis, from records they are the most common found in that drainage and looking at survey records pondhorns have not been found there. We forwarded the picture to a few friends that have worked in the Altahama drainage so hopefully they will get back to me in the next few days.

#8 Guest_UncleWillie_*

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Posted 13 October 2014 - 04:17 PM

Like Bruce said, the overall shape looked "off". The ventral shell margin looked a bit concave and just didn't scream dariensis to me. But now I'm back in my office where I have my reference collection (most of which is from the ACF, but I do have some Altamaha species). I do not have any pondhorns, but here is my largest dariensis from the Altamaha mainstem near Jesup. Looks pretty dang close...

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Edited by UncleWillie, 13 October 2014 - 04:22 PM.


#9 Guest_Skipjack_*

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Posted 13 October 2014 - 04:48 PM

It would be great if we had a member willing to work on a native mollusk ID thread, sub-forum or gallery. An awful lot of us would like to learn more about them, but don't really know where to start. I personally have no clue how you guys narrowed it down this far.

#10 Michael Wolfe

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Posted 13 October 2014 - 07:04 PM

Well, I did not respond to the original "finder" of the item yet. And I am sure that they will love it if I tell them it is a Georgia Elephant Ear!
Either write something worth reading or do something worth writing. - Benjamin Franklin

#11 Guest_Wiz_*

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Posted 14 October 2014 - 01:19 PM

A collegue with the KY Department of Fish & Wildlife Resources forwarded me this picture yesterday but I didn't have time to check out the post on this forum. I provided the following response:

"Its hard to tell for sure from the photo due to the angle but Elliptio dariensis (Georgia Elephantear) is a possibility. The posterior ridge doesn't look quite sharp enough and the shape from the younger growth rests looks more like Elliptio hopetonensis (Altamaha Slabshell). This would make a bit more sense biologically as well since E. dariensis likely uses American Shad as a host. I have not seen E. dariensis upstream of Juliette Dam on the Ocmulgee and this appears to be the most upstream that American Shad can migrate. Elliptio hopetonensis generally is one of the most abundant mussel species we have upstream of the dams in the Altamaha Basin."

I strongly suspect that the individual in question is the Altamaha Slabshell. In general, the Georgia Elephantear tends to have a very sharp ridge with some small corrugations or crenulations on the slope near the very top. They usually are shorter and more inflated than other species the appear similar. The Altamaha Slabshell on the other hand is generally a compressed shell with a "hatchet head" shape to it. The ridge is low and rounded and in my experience, the periostracum (outer covering of shell) tends to be laid down in shingle like pattern with the lower course under the edge of the next course above it. In general, the Altamaha Slabshell tends to be a bit more longer than high which is usually not the case for the Georgia Elephantear.

I've spent quite a bit of time searching for mussels in the Altamaha River Basin but have only found a few mussel species upstream of any of the dams on the Ocmulgee or Oconee. Elliptio hopetonensis appears to be the most abundant by far. I've found then abundantly in the Oconee in the vicinity of Scull Shoals, infrequently in the Apalachee including live individuals upstream of Apalachee Shoals, and abundantly immediately downstream of Lloyd Shoals Dam on the Ocmulgee. I've collected a few in the Yellow River immediately downstream of Cedar Shoals in Porterdale. The other species I've found are the Altamaha Pocketbook in the Apalachee, and some interns I had found a Altamaha Lance in the Oconee near Scull Shoals a few years back.

As mentioned, the Georgia Elephantear doesn't appear to get upstream of any of the dams. This is similar to what we see in the nearby Flint River where the Elephantear (Elliptio crassidens), which was historically known from the entire Flint River, no longer occurs upstream of Albany. The reported host fish for the Elephantear is the Skipjack Herring although any Alosa would probably serve just as well. I beleive that the likely host for the Georgia Elephantear in the Altamaha Basin is also Alosa. We published a note in TAFS in 2013 about American Shad eggs in several freshwater mussel species in the Altamaha River and one of the species that had eggs in them was the Georgia Elephantear. This was also the only species of mussel brooding at the same time that the shad were running. Right now the relationship between the Shad and the mussels is only coincidental but I think that there might be a bit more to it.

Jason

#12 Guest_dac343_*

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Posted 14 October 2014 - 06:17 PM

Thanks Jason, Monte said you would have a good idea on what it might be.

#13 Michael Wolfe

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Posted 14 October 2014 - 09:06 PM

you guys are fantastic! Thanks so much.
Either write something worth reading or do something worth writing. - Benjamin Franklin

#14 Guest_Stickbow_*

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Posted 29 October 2014 - 04:07 PM

Jason, as I was reading your post I almost replied before finishing -- was going to say "if you haven't found mussels above the dams, you need to go to Skull Shoals :).

In Athens -- Just upriver of the middle oconee shoals there's a little park on the north side of oconee street. 25-30 years ago I used to find mussel shells pretty thickly (we used them to temper some repro pottery in an anthro class once)




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