Lampsilis teres (Rafinesque, 1820)
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Basis for Listing
The yellow sandshell was coveted by the pearl button industry because of its beautiful smooth white nacre (inner shell) and evenly thick shell. In Minnesota, it occurred primarily in the main-stem Mississippi and Minnesota rivers (Dawley 1947; Bright et al. 1990). This species is sometimes split into two subspecies or morphotypes: a rayed, generally smaller river morph (Lampsilis teres teres, slough sand shell) and a rayless, mostly big-river morph (L. t. anodontoides, yellow sand shell) (Parmalee 1967; Oesch 1984). Both forms were historically common in the upper Mississippi River (van der Schalie and van der Schalie 1950), however no live specimens have been collected from Minnesota waters in recent decades. It is now one of the rarest mussels in Minnesota. Given its extreme rarity, the yellow sandshell was listed as an endangered species in Minnesota in 1996.
The yellow sandshell has a smooth stout and elongate shell that can reach up to 13 cm (5 in.) long. The exterior of the shell is yellow, occasionally with green rays, and shiny, especially in young mussels. The posterior end of the shell is pointed in males and somewhat truncate in females. The beak sculpture consists of fine and closely spaced wavy ridges. The pseudocardinal and lateral teeth are well-developed, and the inner shell is white. The yellow sandshell resembles the black sandshell (Ligumia recta), the fat mucket (Lampsilis siliquoidea), and the pondmussel (L. subrostrata). The yellow sandshell's beak sculpture and color distinguish it from the black sandshell, its elongate and narrow shell distinguish it form the fat mucket, and its color, size, and thickness distinguish it from the pondmussel.
In Minnesota, the yellow sandshell inhabits large sized rivers. As its name implies, it is at home in fine sediments, but it may also occur in coarse substrates, and in slow or moving current (Parmalee and Bogan 1998).
Biology / Life History
Mussels are long-lived animals. Members of many species may live for several decades and in some instances, a century or more. They spend most of their lives buried in the bottom sediments of permanent water bodies, and often live in multi-species communities called mussel beds (Sietman 2003).
Conservation / Management
The viability of remaining populations of the yellow sandshell in Minnesota is jeopardized by the continuing decline in habitat conditions on the Mississippi River associated with its management as a navigation canal, and with non-point and point source water and sediment pollution. Dams, channelization, and dredging increase siltation, physically alter habitat conditions, and block the movement of fish hosts. The yellow sandshell is also being impacted by the infestation of non-native zebra mussels (Dreissena polymorpha) in the Mississippi River and its tributaries. Zebra mussels can attach themselves in large numbers to the shells of native mussels, eventually causing death by suffocation. In the Minnesota River, land use practices that lead to poor water quality and excessive sediment are the primary factors limiting the yellow sandshell.
Conservation Efforts in Minnesota
A 10-year statewide mussel survey initiated by the Minnesota DNR in 1999 resulted in a better understanding of the yellow sandshell's ecology and current status in Minnesota. A very recently dead shell was found in the lower Minnesota River at Pike Island near the confluence with the Mississippi River in 2000 (M. Davis, Minnesota DNR, pers. comm.), giving hope that this species may still be extant there. Additionally, efforts are underway to propagate juvenile yellow sandshells for restocking into areas where habitat conditions have improved.