INES: a new fuzzy index of environmental integrity for transitional environments

We propose a system constituted by a series of attributes (the input variables), which are integrated through the fuzzy logics to generate a single index to express the environmental quality of estuarine and lagoon habitats, the INdex of EcoSystem impairment (INES). INES combines into a single measure the information held directly and/or indirectly by a complex suite of environmental and biotic attributes, which are known to be of primary importance in the definition of estuarine and lagoon ecosystems health. The data set was gathered in the European transitional waters ecoregion number 6. Several Mediterranean coastal lagoons were considered, and each lagoon was sampled with a seasonal frequency over at least a 1 yr-period. The ecological status classification of the sampling sites was defined a priori (according to the European Directive Proposal 1999/C 343/01) as been high (undisturbed); good (slightly disturbed); moderate (meanly disturbed); poor (heavily disturbed), and bad (extremely disturbed). INES provided a greater degree of sensitivity to degradation in habitat quality, compared to other currently available methods. Furthermore, the strength of INES depended by the univocal response of its input variables. This new multimetric fuzzy index resulted a robust, overall indicator of the response of the natural communities to environmental perturbations, avoiding misleading or ambiguous results.