Biological indices in the terrestrial environment: A brief outline
In terrestrial environment, a large number of biological indices have been proposed. Generally, they are based on the ratio of abundance and/or frequency of different zoological groups of same or different levels. Insects are particularly solicited. Carabic Coleopterae are frequently considered as good indicators of the transformation of terrestrial ecosystems and are in this way used in the indices. Most of these indices are empirical, even if 'workable'.
Biological indices in continental waters: an outline
Diatomic and macrophitic indices are currently used in running waters and in lakes. Macroinvertebrates and fish have conducted to biotic indices used in many countries, especially in Europe and North America, to establish legal norms. Innumerable indices are designed, specialized according to criteria such as geographic areas, nature of bottom, altitude, depth, speed of current, light, turbidity, etc., in correlation with the floristic and fau-nistic composition and functioning of communities. Considering this, filling the gap between biotic indices to a 'global biological index' is needed. The protocol of this global biological index is much more detailed than for the individual indices. It constitutes a synthesis of the expression of the general biological quality of a given station: all causes considered and mixed together. It has to be considered as a very final goal.
In the past few years, interest in benthic indicators in marine environment has dramatically increased after a rather long period of relative stagnation. This change is mostly due to the need for new tools to assess the status of marine waters within the precinct of some regulations elsewhere, that is, the European Water Framework Directive. In this context, a certain number of new indicators and indices have been proposed. Most of the pollution indices have been created from 'subjective' or 'objective' biological indicators as previously pointed out.
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