Using Fish Communities to Assess Streams in Romania: Initial Development of an Index of Biotic Integrity*

Abstract

Multimetric biotic indices increasingly are used to complement physicochemical data in assessments of stream quality. We initiated development of multimetric indices, based on fish communities, to assess biotic integrity of streams in two physiographic regions of central Romania. Unlike previous efforts to develop such indices for European streams, our metrics and scoring criteria were selected largely on the basis of empirical relations in the regions of interest. We categorised 54 fish species with respect to ten natural-history attributes, then used this information to compute 32 candidate metrics of five types (taxonomic, tolerance, abundance, reproductive, and feeding) for each of 35 sites. We assessed the utility of candidate metrics for detecting anthropogenic impact based on three criteria: (a) range of values taken, (b) relation to a site-quality index (SQI), which incorporated information on hydrologic alteration, channel alteration, land-use intensity, and water chemistry, and (c) metric redundancy. We chose seven metrics from each region to include in preliminary multimetric indices (PMIs). Both PMIs included taxonomic, tolerance, and feeding metrics, but only two metrics were common to both PMIs. Although we could not validate our PMIs, their strong association with the SQI in each region suggests that such indices would be valuable tools for assessing stream quality and could provide more comprehensive assessments than the traditional approaches based solely on water chemistry.