Thursday, October 9, 2008

Unionid Mussels

One of the most imperiled classes of animals in North America are the Unionid Mussels. There are 11 species of mussels on the Kansas Threatened or Endangered species list, and there are more that are definitely in need of conservation. Historically, these species were harvested for buttons (like on your shirt), and a massive industry existed within Kansas to harvest these species out of the Arkansas River, Verdigras River, and Neosho River (to name a few). Massive water quality issues compounded the mussel's decline through the early part of the 1900. Even into the 1970s, the mussel-rich portions of Kansas waters were experiencing massive fish kills due to runoff from feedlots and poor municipal water treatment facilities. Once the Clean Water Act came along and cleaned up the water (the importance of the CWA can never be understated), the surviving mussel populations were isolated by impoundments and low-head dams. Consequently they've been slow to make any kind of comeback. This is why KDWP is propagating mussels in an effort to circumvent barriers that are isolating them. The initial results of this are quite promising, but I should really save that for another post.

Regardless, last week I went out and did a mussel survey and relocation. A temporary stream crossing will be going across the Verdigris River, and we came to insure no mussels were harmed. In particular we were looking for the Ouachita Kidneyshell Mussel (Ptychobranchus occidentalis), and we were unsuccessful in finding it. We did find shells from 13 mussels, and live individuals from 5 (about 20 individuals overall), including a couple that are fairly rare. Hope you enjoy the pics:

The Verdigris River. If you look closely, you can actually see a lot of mussel shells on the stream-bottom and on the gravel bar even in this picture. There were literally thousands of mussel shells here.

A fairly common species, the Pistolgrip (Tritogonia verrucosa).

A smaller Pistolgrip and a White Heelsplitter (Lasmigona complanata complanata).

A Threeridge (Amblema plicata plicata). I got these confused with Washboard (Megalonaias nervosa), but I guess the key is the area where the ridges begin. In a Washboard there would be distinct 'patterning' there (the overall body shape is different as well). Incidentally, the three ridges are not characteristic (more ridges will form if the animal is given enough time to grow), but they were harvested for buttons only when they were large enough to have 3 ridges. These are thick, heavy shells that would probably make a lot of buttons.

We packed all the live mussels into a bucket and moved them upstream, so that erosion caused by the stream crossing wouldn't affect them. We also found some live Pimplebacks (Quadrula pustulosa pustulosa), Mapleleaf (Quadrula quadrula), and Bleufer (Potamilus purpuratus).

I didn't really dump them all in one location, but we forgot to take pictures of us putting the live ones back in the river. This is our 'creative recreation' of the event.

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