Biomonitoring of fish communities, using the index of Biotic Integrity, as an indicator of the success of soil conservation measures in the Rabbit Creek and Middle Creek watersheds, Macon County, North Carolina
Description: Fish communities in two upper Little Tennessee River tributaries, Rabbit Creek and Middle Creek, both located in Macon County, North Carolina, were monitored using IBI methods in 1990 and again in 1992. A single site, each on the lower reaches of its respective creek, was chosen to reflect the influence of conditions throughout the watershed and to provide a measure of water quality exiting the watershed. The Rabbit Creek watershed (Holly Springs community) has a long history of settlement and agricultural use. Dominant land uses today are pasture in the bottom lands and residential development at higher elevations. Much of the upper portion of the Middle Creek watershed on the slopes of Scaly Mountain is devoted to cabbage farming, often on steep slopes and highly erodible soils. From the cabbage growing area, the creek drops 400 feet to the lower valley. Other common land uses include residential, livestock, and forest. Both streams are characterized by heavy sedimentation and frequent high turbidity. Both streams showed marked improvement between 1990 and 1992. In 1990, Rabbit Creek`s IBI score was 31.0, for a bioclass rating of ``poor.`` In 1992, the IBI score was 42.1 for a bioclass rating of ``fair.`` For Middle Creek, the corresponding figures and ratings are 42.1 (fair) and 54.5 (good). Examination of the data for Rabbit Creek shows a reduction in the proportion of pollution-tolerant species, a higher proportion of specialized insectivores, a higher catch rate (reflecting higher total numbers of fish), and an additional intolerant species. In both cases, the data (supported by visual observation) suggests the causative factor is reduced sedimentation.
Date: August 1, 1993
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