An index of biotic integrity for fish assemblages in Ozark Highland streams of Arkansas

We developed an Index of Biotic Integrity (IBI) for wadeable Ozark Highland streams in Arkansas by using fish-assemblage data from 96 stream sites. All sites were classified as reference or non-reference based on both subjective and objective information, and we used uni- and bivariate statistics to examine 39 potential IBI metrics. Seven metrics were chosen for the IBI. They were percent (of individuals) as algivorous/herbivorous, invertivorous, and piscivorous; percent with black spot or an anomaly; percent green sunfish Leponfis cyanellus, bluegill L. macrochirus, yellow bullhead Ameiurus natalis, and channel catfish Ictalurus punctatus; percent invertivorous; percent top carnivores; number of darter Etheostoma and Percina, sculpin Cottus, and madtom Noturus species; and number of lithophilic spawning species. Trophic metrics contributed most to IBI scores, and metrics were most often correlated with chloride, nutrient, land use, road density, and sedimentation levels, which suggests that our IBI should be able to successfully differentiate stream conditions in wadeable Ozark Highland streams of Arkansas.