Mussel Biodiversity

Why study mussels? | Surveys of Oklahoma Rivers | NSF Biodiversity Project

Why Study Mussels?

The freshwater mussel (Mollusca, Bivalvia, Unionidae) fauna of North American rivers and streams is the most diverse in the world, but is highly threatened and declining at an alarming rate. The consequences of this catastrophic decline of an entire family go beyond the loss of species. Mussels serve critical trophic and non-trophic roles in the functioning of riverine ecosystems. Because mussels can achieve very high densities and are filter feeders, they are important seston consumers and play a significant role in both energetics and particle dynamics in rivers. Because of their dependence on appropriate substrate and flow conditions, mussels are naturally patchily distributed in many rivers, occurring in densely aggregated multi-species "beds". The living mussels and their spent shells in these beds provide habitat for other benthic macroinvertebrates, alter hydraulic and sediment dynamics at the benthic-water interface, and stabilize the substrate. Through their feeding activities mussels provide nutrients to the remainder of the benthos. Thus, the current decline in mussel species also represents a loss of critical habitat and food resources for other aquatic fauna, and may alter the ecosystem functioning in many North American rivers. In addition, there are likely benthic macroinvertebrates that have coevolved with mussel assemblages and are specifically dependent on them. No one has ever surveyed the benthic invertebrates specifically associated with mussel assemblages. As mussel populations decline these other invertebrates species are also being lost.

Surveys of Oklahoma Rivers

The Oklahoma Biological Survey is conducting surveys of the freshwater mussels of the major rivers in Oklahoma. We have completed surveys of the Little, Glover, Kiamichi, Mountain Fork, Blue, Illinois, Spring, Neosho, Caney and Verdigris rivers, portions of several other major rivers, and numerous smaller streams. Species lists for the above rivers are available upon request.

NSF Biodiversity Project

The Oklahoma Biological survey is surveying freshwater mussels, and the macroinvertebrate fauna associated with assemblages of mussels, in rivers throughout the Ouachita Mountains Physiographic Subprovince in central and western Arkansas and southeastern Oklahoma, U.S. with funding from the Biotic Surveys and Inventories Program of the National Science Foundation. The Ouachita Uplands represent one of the last strongholds of freshwater biodiversity in North America, and may represent one of the last strongholds of freshwater mussel biodiversity in the world. The Ouachitas are unglaciated and have been isolated from other mountain systems for 225 million years. They are a center of speciation for both terrestrial and aquatic organisms, with a high number of endemic species. The rivers have been far less impacted by human disturbance than faunas of more eastern and western U.S. rivers, largely because the area is relatively unpopulated and undeveloped. Thus, the rivers of the Ouachita Uplands may represent one of the few areas in North America where conservation of an intact mussel fauna may be possible.

Mussel and benthic macroinvertebrate voucher specimens are being deposited in appropriate museums and mussel tissue samples are being deposited with the U.S.G.S. Leetown Science Center genetic tissue repository and the Texas Parks and Wildlife Heart of the Hills Research Station. Mussel and benthic macroinvertebrate data will made available on the dedicated World Wide Web server of the Oklahoma Biological Survey and published in the peer-reviewed literature. In addition, the data collected on the distribution of freshwater mussels and associated benthic macroinvertebrates also will be applicable to a diversity of conceptual problems in biology, many of which have important conservation implications. Finally, because the data to be collected are quantitative, they will serve as invaluable baseline data for monitoring these sites in the future. We will be able to tell if species or communities are faring poorly before they are in danger of going extinct by comparing long-term abundance, composition, and demographic patterns. In particular, this project will provide baseline data for determining the effects of an invasive exotic species, the zebra mussel, on the declining, native mussel fauna.

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