A Biotic Index (Lambda)) for Measuring the Ecological Quality

This study presents a biotic index (?) for measuring environmental quality in the coastal lagoons of the Mediterranean. Index ? considers combined anthropogenic (pollution) and natural factors (prohibitive salinity, anoxia, toxic blooms, isolation from sea, etc.) of deterioration. The method is based on the principle of indicator species and on the conceptual scheme developed by Frisoni et al. (1984) according to which there are six possible sub-assemblages (Zones) of benthic macrofauna, each indicating a different level of environmental quality. The procedure requires defining the relative extent of the Zones in the lagoon under study, and the number of species and the mean biomass of benthic macrofauna present in each. The three metrics are applied in the index formula and the resulting number from one to ten indicates increasing environmental quality. The authors have validated the index by applying it to two lagoons, Lesina and Varano (S.Adriatic, Italy).