1. Introduction
Bioindicators are organisms that rapidly reveal the quality
of an environment, by highlighting the effect of environmental
changes on a population, community, habitat or even on an
ecosystem [1]. On the basis of this characterization, bioindicators
are useful in assessing additive, synergistic and
antagonistic effects upon living organisms within a broad
pollutant-based spectrum of complex environments [1,2]. In
the last few decades, several bioindicators for freshwater environments
have been thoroughly studied. Most of these organisms
are macrobenthic invertebrates, algae and
microorganisms [3e5]. Depending on the type of organism
chosen, there exist a variety of scales that can be examined by
biomonitoring: individual, multi-population and communityrelated
[1,6,7]. For example, aquatic macroinvertebrates can
be considered sensitive sentinels in polluted freshwater; analyses
show they can be recorded at different ecological levels.