The spectaclecase (Cumberlandia monodonta) is a freshwater mussel that the U.S. Fish and Wildlife Service listed as an endangered species. It is found in the Mississippi, Missouri and Ohio River basins. The spectaclecase is considered a specialist species that requires very specific habitat needs, which limit its current range and distribution to certain sites within large rivers. Generally, mussels are long-lived, with individuals surviving up to several decades, sometimes up to 100 to 200 years. The oldest documented spectaclecase was thought to be 70 years old!

Major threats to the spectaclecase mussel include dams, small population size and fragmentation, sedimentation and pollution. Population losses due to dams have contributed more to the decline and potential extinction of the spectaclecase than any other factor.

Dams affect both upstream and downstream populations by disrupting seasonal flow patterns, scouring river bottoms, altering water temperatures and quality, and eliminating river habitat. Large rivers throughout nearly all of the spectaclecase mussel’s range have been dammed, leaving short, isolated patches of habitat between dams. Spectaclecase mussels likely depend on a fish, or other aquatic species, to move upstream. Because dams block fish passage fish passage
Fish passage is the ability of fish or other aquatic species to move freely throughout their life to find food, reproduce, and complete their natural migration cycles. Millions of barriers to fish passage across the country are fragmenting habitat and leading to species declines. The U.S. Fish and Wildlife Service's National Fish Passage Program is working to reconnect watersheds to benefit both wildlife and people.

Learn more about fish passage , mussels are also prevented from moving upstream. This isolates upstream populations from those downstream and leads to small, unstable populations. Consequently, these smaller populations are more vulnerable to other threats.

Impoundment and channelization of rivers and streams further impacts these endangered mussels because of the increase in sedimentation and siltation. The 2014 recovery outline for the species notes that excess sedimentation, for example, reduces the feeding and respiratory efficiency of the mussels. Additionally, slow-moving deep water is created by impoundments which are perfect habitat for certain species such as the exotic zebra mussel, which poses a serious threat to native mussels.

The mostly sedentary lifestyle of these animals renders them more vulnerable to toxins and degraded water quality from pollution. Contaminants from accidental spill, factory discharge, sewage treatment plants and landfills and runoff from field feedlots, mines and construction sites can directly kill mussels. Indirectly, contaminants reduce the water quality, affecting the ability of surviving mussels to reproduce and lower the numbers of host fish.