|Tour Stop #4: Incised Stream Corridor Habitat Rehabilitation|
S. S. Knight F. D. Shields, Jr.
Channel incision has major adverse impacts on stream corridor ecosystems. As channels deepen and widen, pool habitats are lost, riparian vegetation is destroyed, and woody debris becomes less common within the channel. Baseflows are characterized by extremely shallow flow over shifting sand beds. Conceptual models of incised channel evolution and warmwater stream fish community structure may be used to guide stream habitat rehabilitation. These models indicate fish communities are generally adversely impacted by channel incision and the associated widening. As temporal stability and pool habitat availability decline, larger individuals of pool-dwelling species become rare or absent. Effects may be partially reversed by natural recovery or by rehabilitation projects that increase the availability of stable pool habits. In a five year study of two restored streams, fish communities generally responded as suggested by the aforementoned conceptual model. Species composition shifted away from small colonists (principally cypdnids and small centrarchids) toward larger centrarchids, catostomids, and ictaludds. Major gains in stream ecosystem rehabilitation can be made through relatively modest but well designed efforts to modify degraded physical habitats.
Key Words:Stream restoration, Fish, Erosion, Sediment Physical habitat Biotc indices, Woody vegetation, Riprap, Community structure
Publications:Knight S. S., Cooper, C. M. and Shields, F. D., Jr. 1995. Ecological evaluation of watershed management projects. Proceedings of the Second International Conference on Hydroscience and Engineering, Tsinghua University Press, Beijing, 813-821.
Shields, F. D., Jr., Knight S. S., and Cooper, C. M. 1994. Effects of channel incision on base flow stream habitats and fishes. Environmental Management 18(l):43-57.
Shields, F. D., Jr., Cooper, C. M., and Knight S. S. 1995. Experiment in Stream RestDraton. Journal of Hydraulic Engineering. 121(6): 494-502.
Shields, F. D., Jr., Knight S. S., and Cooper, C. M. 1995. Incised stream physical habitat restoration With stone weirs. Regulated Rivers: Research and Management 10:181-198.
Knight S. S., Shields, F. D., Jr., and Cooper, C. M. 1996. Ecological studies on the Demonstration Erosion Control Project in the Yazoo Basin. In Proceedings, Sixth Federal Interagency Sedimentation Conference, Vol. 1, pp. 11-6-41-13.
Cooper, C. M., Testa, S., 111, and Shields, F. D., Jr. In Press. Invertebrate Response to Physical Habitat Changes Resulting from Rehabilitation Efforts in an Incised Unstable Stream. In Wang, S.Y., Langendoen, E. and Shields, F. D. Jr., (eds.) Management of Landscapes Disturbed by Channel Incision, Stabilization, Rehabilitation, and Restoration, University of Mississippi, University, Mississippi.