Application of an index of biological integrity (IBI) to fish assemblages of the rivers Khan and Kshipra (Madhya Pradesh), India

1. A multimetric index of fish assemblage integrity was developed and similarity analyses were conducted on fish species in two central Indian rivers and the effects of distance from municipal and industrial effluents on those indices then evaluated. 2. Five metrics from Karr et al. (1986, Illinois Natural History Survey Special Publication 5, Urbana, IL) were adopted: intolerant species richness, % omnivorous individuals, % top carnivore individuals, total number of individuals and % individuals with anomalies. Seven new metrics (native species richness, native family richness, benthic species richness, water column species richness, % non-native individuals, % tolerant individuals and % herbivorous individuals) were added. 3. Non-native individuals represented 1-55% of the assemblages at sampled sites which held fish. 4. Fish were present at eleven sites and not collected at two sites, despite heavy metal concentrations exceeding U.S. Environmental Protection Agency acute criteria at all sites. 5. Two types of metric scoring were examined. The traditional 5-3-1 method showed the same pattern as continuous scoring from 0 to 10, but produced a higher integrity class at one site. 6. Scores on our modified index of fish assemblage integrity increased with distance downstream from a major effluent source in each river. Jaccard similarity scores between the least disturbed downstream site and all other sites decreased with increasing distance and disturbance. 7. It was concluded that Karr's original index and its theoretical foundations are easily adaptable, even to an ichthyofauna containing no species, and only two families (Cyprinidae, Poeciliidae), in common with the midwestern United States.