MISSOURI
40% of the nation’s fish and 70% of freshwater mussel species are listed as imperiled
The Osage River © tomofbluesprings
Habitat for Mussels
Preserving Biodiversity in Missouri’s Rivers It may seem obvious, but water is the primary forming force of a river. Natural streams experience variable flows seasonally and across the years; streams may be confined to a thread of water during extreme droughts or may swell to fill their floodplains during periods of high precipitation. Periods of low flow provide opportunities for vegetation to establish or recover along the banks and concentrate food sources for freshwater predators. During a flood, the force and volume of water can move the riverbanks, changing the course of the river for years. The water level in the stream can even cue migration and breeding cycles for some species of fish, mussels and birds. When a dam is placed on the river for hydropower or flood control, the flow releases are relatively stable, reducing the variability that healthy streams rely on to support biodiversity. The Nature Conservancy partners with the U.S. Army Corps of Engineers (USACE) to gather resource professionals’ input, collect biological information on the flow requirements of the many species that live downstream of the reservoir and solicit flow recommendations from a variety of stakeholders. The ultimate goal is to release water in a way that supports biodiversity and healthy stream function. In Missouri, TNC has partnered with USACE on the Osage River near Kansas City and the Black River in the southeastern part of the state. The Osage River in Missouri begins as the Marais Des Cygnes in Kansas before crossing the state line, joining the Little Osage River and flowing through Truman Lake on its way to join the Missouri River. Stockton Lake and Pomme De Terre Lake also flow into the Osage River system. The Black River rises out of the St. Francois mountains in eastern Missouri before it hits Clearwater Lake upstream of Poplar Bluff, and then flows into Arkansas, where it joins the White River and eventually the Mississippi.
Elephantear mussel © U.S. Fish & Wildlife Service
Mussel populations continue to decline in many watersheds from a variety of impacts. The elephantear mussel is one of the rarest species in Missouri. Within the state, its largest populations are concentrated in the Meramec and Gasconade rivers, but it is also found in very low numbers in the Osage River. Like all mussels, the elephantear filters the water to obtain its food and reproduce, cleaning the water that passes through. Environmental flow management on the Osage River would benefit mussel species such as the elephantear, resulting in improved biodiversity and cleaner water for people and wildlife thanks to these natural water filters.
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Missouri missouri@tnc.org nature.org/missouri
The Nature Conservancy P.O. Box 440400 St. Louis, MO 63144
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