Abstract

  
  Macroinvertebrate and fish assemblages are integrally linked to in-stream physical and chemical characteristics. The Choctawhatchee-Pea watershed in southeast Alabama lies entirely in the Coastal Plains ecoregion. Activities such as agriculture, silviculture, road maintenance, and urban development combined with the highly erodible soils characteristic of this region contribute non-point sources of pollution to Alabama's streams through polluted runoff and habitat alteration. Biological monitoring may be the most appropriate means of detecting pollution effects on aquatic communities, and development of biological criteria is important for the establishment of enforceable laws regarding nonpoint source pollution. This study was done to evaluate biological integrity expectations of wade-able streams in the Choctawhatchee-Pea Rivers watershed using the multimetric approach. Fish and macroinvertebrate assemblages, in-stream habitat features, water quality, and land use were quantified in an agriculturally developed watershed in order to relate overall biotic integrity to patterns of water quality and habitat structure. Thirty-four randomly selected stream sites, sampled in late spring, 2001, were used to calibrate a fish index of biotic integrity (IBI) and an invertebrate community index (ICI). An additional fifteen sites, seven least impacted and eight impacted, along with habitat indices were used to validate the indices. The stream condition categories of urban and pasture had significantly lower IBI scores than did the least-impacted sites, while row crop sites were not significantly different. For the ICI, all stream condition categories were significantly lower than the least impacted sites. Method validation suggests that our sites may reflect only a small portion of the dose-response curve or that all sites in the area have been generally degraded by past land use practices.