Freshwater Mussels


freshwater musselsFreshwater mussels are considered one of the most threatened groups of organisms in the world. The small rivers of the tallgrass prairie region of Oklahoma were once home to a wide array of freshwater mussels. Studies in the 1920’s showed that the Verdigris, Caney and Neosho Rivers in northeastern Oklahoma were relatively good mussel habitat. However, since that time there have been significant declines in mussel populations in these rivers. Loss of native mussels has been attributed to habitat alteration, pollution and invasive species.

Dr. Joe Bidwell and Ph.D. student Chad Boeckman at Oklahoma State University began a study in the summer of 2006 to examine mussel populations in the tallgrass prairie region. They sampled 31 sites, which had previously been sampled about ten years earlier, from the Oklahoma-Kansas border to below Oologah Lake. In 2007, they sampled 29 sites in the Caney River that had also been examined ten years ago.

In the Verdigris River a significant increase in number and amount of species was found in comparison with the 1997 study in that area. Two species of mussels that were thought to have been lost from the area were also found, the western fanshell and the rabbitsfoot mussel. The western fanshell has a pattern of green rays on its light brown shell and the rabbitsfoot mussel is named so because of its shape.

In the Caney River it was determined that there had not been any significant declines in mussel abundance since the 1997 study.

In addition to examining the freshwater mussel populations, these researchers are also examining fish and invertebrate populations in the area and looking for zebra mussels. Zebra mussels are an invasive species of mussel that reproduce rapidly. In zebra mussel infested waters it is not unusual for native mussels to be completely covered by zebra mussels. Competition for food and oxygen weakens and eventually starves native mussels.

This study is ongoing, and will continue to examine the status of invertebrates, fish and freshwater mussels in the tallgrass prairie region of Oklahoma.