(Doledec and Statzner, 2010). In North America, Karr (1981)
initiated the first studies based on the multimetric index (MMI)
approach, in which attributes of fish assemblages (metrics related
to species richness and composition, trophic composition,
abundance, and health status) were used to evaluate anthropo-
genic pressures on a stream and its watershed ecosystem. Metrics
are scored according to reference conditions, which are preferably
defined as those expected to have minimal or no human
disturbance in a stream of similar size in the same region. The
sum of these ratings provides an index of biotic integrity (IBI) that
is regarded as an integrative and quantitative measure of local
biological integrity or overall human impact (Karr, 1991; Doledec