Fish-Based Index of Biological Integrity (IBI) for Freshwater Ecosystems

The Indices of Biotic Integrity (IBI) are becoming increasingly used as tools for providing scientific information for environmental impact assessment and further research. The Fish-based Index of Biotic Integrity (Fish-IBI) was developed in the early eighties as a tool to classify and rank the environmental quality of aquatic habitats. The Fish-IBI methodology was designed to use biological components (metrics) to determine the relative health of the aquatic environment. The metrics usually included measures of taxonomic richness, habitat and trophic guild composition, dominant species, intolerant and tolerant species, disease health or anomalies, totally 12 metrics. The main criteria for a metric are that it demonstrates a range of values across a gradient of environmental quality and is expected to be found in most aquatic ecosystems. The most common type of scoring for Fish-IBI is the 1-3-5 criteria. Poor habitat quality is scored as 1, moderate habitat quality is scored as 3 and good habitat quality is scored as 5, comparing to the reference site. Each Fish-IBI metric is scored individually and then summed together to create an overall Fish-IBI score for the study site. The overall Fish-IBI calculated ranged from 12 to 60, which can be used to determine the relative health of the site. Using the habitat quality ratings proposed by Karr (1981), the fish habitat ranged 5 levels across the sampling locations are very poor, poor, fair, good and excellent respectively. This paper reviewed the Fish-IBI methodology and the applications for assessing the aquatic ecosystem health, conducted by various researchers. In each case show and discuss on its application. Keywords : Index of Biotic Integrity (IBI), indicator, metrics, habitat quality