Ten Years After: Stream Habitat Restoration Project in Retrospect

Abstract

Long-term assessments of ecosystem rehabilitation project effects are rare. Herein we describe a study of the Hotophia Creek rehabilitation project in northwest Mississippi. The stream channel was subjected to channelization ca. 1963 and experienced rapid channel erosion between 1963 and 1985, with annual suspended sediment yield exceeding 1,000 t km –2 . More than $10 million were expended on erosion control measures within the 90-km 2 watershed between 1985 and 2000, with an attendant sixfold reduction in suspended sediment yield. Fish and physical aquatic habitat data were collected for one year prior to construction of a one-km long stream habitat rehabilitation project in 1992. Habitat rehabilitation consisted of extending existing stone spurs, placing stone toe, and planting willow cuttings. Post construction monitoring was conducted for the four years following construction, and at 10 years following construction. Parallel monitoring was conducted on an untreated reference stream and on untreated reaches upstream on Hotophia Creek. Effects of rehabilitation on habitat and fish communities were found to be positive in both the short and long term. For example, after 10 years, mean water depth in the reach subjected to rehabilitation was more than twice as great as for untreated reaches upstream. Woody riparian vegetation more than doubled and large woody debris density increased by an order of magnitude in both treated and untreated streams. Fish species richness and numbers were lower after 10 years, perhaps due to reduced sampling efficiency associated with greater water depth. However, fish populations shifted away from domination by large numbers of small, opportunistic generalists and toward dominance by large-bodied, pool-dwelling species typical of more pristine streams. Prior to rehabilitation, 51% of the fish captured were cyprinids (minnows), while 10 years later 61% of the fish captured were centrarchids (sunfishes).