25 January, 2015 Bivalves and bryophytes – who even knew?
Shellfish were the farthest thing from my mind when I began this project (Every living thing) late last year. Seriously – seafood? Pony Pasture? It was not on my radar. It’ll be a while (if ever) before I produce any living specimens of freshwater mussels. I am not going into that river until April at the earliest. But some industrious eater leaves mussel shells on the riverbank all the time. Raccoons are my first guess, but I’m sure Great Blue Herons eat them too. I find shells every time I’m at Pony Pasture, but there are never any tracks around them.
The first one I photographed was, fittingly, in a hole in a tree stump – with a moss. The scientific name for mosses is “bryophytes.” Washed in there from a flood or a bird or a child or who knows how it got in there:
They don’t photograph well. Maybe in the summer when I get some live ones they’ll be more picturesque. That one in the picture is larger than many I’ve found. Although there’s nothing here for scale (I regret to say) this one is smaller than the one in the preceding picture. This one is maybe as big as a quarter:
Even a quarter-sized bivalve is larger than the vast majority of clams and mussels I find on the riverbank. Here’s a little pile I ran across – sorry about the quality of the picture. Most are the size of a nickel or a dime or even smaller. There can’t be a whole lot of calories in there but it’s pure protein. And I suppose a bit of fat. And a predator doesn’t burn up any calories chasing after it:
I learned a few interesting things when I was researching this post. One thing I learned was I have a lot to learn about freshwater mussels! They’re not real popular like butterflies or birds and you don’t see them often. So the available resources are slender. Here’s a fact I find fascinating: The United States has 304 species of freshwater mussels. Africa – the entire continent – is in second place – with 96 species. The continent of Africa is large enough to hold the United States three times inside it. But we have more than three times the number of freshwater mussels. I found this sentence on the Virginia Department of Game and Inland Fisheries (VDGIF) page of freshwater mussels: “The diversity of freshwater mussels in the United States is unmatched.” Exquisite understatement.
Many of the bivalve shells I’ve found – most, really – are clams, not mussels. I put a caveat in a preceding paragraph about the shortage of research resources about freshwater bivalves. That was to set myself up for the fact that I have thus far been unable to make a positive ID on any of them. But I am relatively certain a number of those shells come from the Asian Freshwater Clam (Corbicula fluminea).
The research on their environmental effects is easier to come by. The Zebra mussel (Dreissena polymorpha) is overwhelming some bodies of water in the US but our James River is not one of them. Our freshwater clams and mussels overpopulate intermittently but are generally benign. They’re a food source for so many fish and birds and mammals here that they don’t often go unchecked. They also constantly filter the water and keep particulate matter out of it. They’re called “filter feeders.”
Also – this is important – a lot of this is just my take on it. A conservation expert or even a well informed amateur knows a lot more than I do and may take strong exception to this. If you’re interested, I suggest you research it more. Just because the information is difficult to find doesn’t mean it’s not out there. Here in Virginia, there is a comprehensive program aimed at bringing our freshwater bivalve population back into balance. If you’re interested in learning about the program, I suggest you read up on it in this comprehensive publication by the VDGIF: Regaining Our Freshwater Mussel Heritage
The VDGIF is an informative resource for information about mussels. Recall that the “IF” at the end of that abbreviation stands for “Inland Fisheries.” But it is not for amateurs. And although I am keenly interested, I am in all things regarding mussels an amateur. But I’m going to provide a link to a “freshwater mussel restoration” survey they did in southwest Virginia in 2008. It’s forty-seven pages long, and while it’s written about an animal that spends its entire life underwater, it’s quite dry. Until page 47, when they begin listing the common names of mussels. It lists over thirty different mussels. I’d like to list them all, but here are five favorites – you should check out the list for yourself. They’re all great. Look at these five: purple wartyback, Tennessee pigtoe, Appalachian monkeyface, rayed bean, pink heelsplitter – how could that be any more fun? Trust me, that hardly scratches the surface. Here’s the site; you have to go to the bottom (page 47) to read all these superb names: Freshwater Mussel Survey of Cleveland Island, Clinch River, Virginia: Augmentation Monitoring Site: 2008.
I’m nearly out of time! And I haven’t put in anything about bryophytes! That’s a fancy name for mosses! Possibly because I don’t have a ton of data. I’ll gradually get some in.
Next week I’ll go back to more traditional (whatever my tradition is) blogging. More pictures. Meanwhile, I got to dog sit this weekend for my friend Pat and Megan’s dogs. It’s always fun to take them to Pony Pasture with Mackey and Turner on Sunday morning. Although believe me, I don’t do much quality photography when I hike with four dogs. Here are two pictures from this morning – one with the four of them crossing Charlie’s Bridge:
And one with the four of them at the edge of the river:
Also, I’ve put way too many pictures of Ring-billed gulls on here, but I took a nice one earlier this week and they’re pleasant. And I’m short on pictures this week!:
In the same spot I took a quick picture of the water flowing over rocks; I could stare at this all day:
See you in a week!
PS I will include a bryophyte after all – although I got this one out of my yard, not from PP. This is the one I’ll use to teach myself to identify mosses. My friend recommended a book called Common Mosses of the Northeast and Appalachians (McKnight, K, 2013).
Take a look:
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It’s been well over two years since my Dad died, and my current level of sadness is an appropriate one – it’s not that big of a deal. But when I’m researching something arcane for this blog I really miss him. Because he was the most intellectually omnivorous person I’ve ever known. He really didn’t like not knowing something. And if he didn’t know something (say, the common name and scientific name of an obscure freshwater mussel), he’d learn how to learn that. Dad was seventy-seven when he died and although it was sudden and unexpected, I’ll bet he learned something new earlier that day. I think learning was like scratching an itch for dad. He just did it because it felt good. I think if dad wasn’t feeling well, it made him feel better to learn something.
My “Every living thing” project, a.k.a. “Pony Pasture Flora and Fauna” has completed its main growth stage. I’m close to ninety combined species of plants and animals in Pony Pasture. You can check them out on the “Every living thing” site. I’ll “get” a lot more “specimens” as the year goes on. Lots of insects and lots of flowering plants – you don’t see those in January – and a few more birds and reptiles and amphibians. I always feel like I’m channeling my dad when I’m working on this, and I love that feeling. I’ll keep it up.
Have a great week!
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Otters eat them. The top of our dam is littered with shells (unfortunately the dam is now riddled with otter tunnels so as much as I enjoy watching them play they have to go or we’ll lose the lake)
According to multiple sources, otters do not dig their own dens or tunnels.
VDGIF website says river otter dens are in ….’ (overhanging banks, tree knots and abandoned streambank burrows). This species does not dig its own burrow…..’
and ….’Nest/den sites are in woodchuck burrows, tree stumps that are near rivers, and other such sites that are above high water lines….’
Maybe groundhogs are doing that extensive tunneling.
According to wildlife sources, otters are not the ones creating your tunnel problems.
From the VDGIF website on river otter life history (http://www.vafwis.org/fwis/booklet.html?Menu=_.Life+History&bova=050045&version=16461)
…’ natal den (overhanging banks, tree knots and abandoned streambank burrows). This species does not dig its own burrow….’
…’Nest/den sites are in woodchuck burrows, tree stumps that are near rivers, and other such sites that are above high water lines….’
Sounds like a groundhog or muskrat problem. Both of those species are master burrowers ….