Analysis of inland waters

Analysis of inland waters

ERSE carries out analysis of inland waters in Tuscany and the rest of Italy, using the following synthetic indexes.

EBI (Extended Biotic Index)

The EBI relies on the analysis of benthic macroinvertebrates communities colonizing the river ecosystems, especially on the qualitative-quantitative comparison between the sampled macrobenthic population and a generic population “expected” in free of anthropic impact habitats. Changes in the population’s composition are related to the set of effects provoked over time by different causes of disturbance (physical, chemical and biological). These changes are translated into numerical values by the Index and in turn linked to an ecological quality class.

MacrOper System (STAR_ICMi)

The STAR_ICMi index (STAndardisation of River classifications_Intercalibration Common Metric index) allows to derive a quality class using macrobenthic organisms as indicator, defining the ecological status of the station in question, according to the requirements of the Water Framework Directive (WFD: 2000/60/EC). The main differences compared to other indexes based likewise on macrobenthos are: a sampling that is replicated according to the representativeness of the varied types of microhabitats present; the count of each systematic unit detected replacing the determination for presence/absence; the calculation of the index derived from six suitably weighted independent metrics.

EPI-D and other Diatomic Indexes

Diatomic indexes are intended to define the ecological status of a stream based on the specific composition of benthic diatom’s population (Bacillariophyceae). These indexes are weighted on the characteristics of the individual species (such as sensitivity to pollutants, ecological plasticity, relative abundance within the population): the values obtained can be referred to Quality Classes established in advance, or to reference conditions calculated for each river macro-type, as required by Directive 2000/60/CE. The EPI-D (Eutrophication/Pollution Index-Diatom based) is the only index developed for the Italian territorial context, but it does not comply with the European water directives and cannot be used to determine the ecological quality ratio (Ecological Quality Ratio: EQR). Contrariwise, the Multimetric Intercalibration Index (ICMi) complies with the requirements of Directive 2000/60/EC. Additional diatomic indicators (such as TDI, TI, IPS, SI, IBD, IDG) may be calculated, upon agreement, based on specific customer requests.

Indexes for Quality Assessment in Lakes

The biological elements used as indicators are those most susceptible to stress, such as phytoplankton, macrobenthos or benthic macrophyte communities. The indexes listed below comply with the Directive 2000/60/CE “Water Framework Directive”.

  • The MedPTI index is applicable to low and medium altitude subalpine reservoirs (up to 800 m a.s.l.): the biovolume of each phytoplanktonic species is considered, weighted for both its trophic and indicator value.

  • The PTIspecies index, applicable to deep subalpine lakes (<-120m), is also based on the biovolume of phytoplankton species, proportionate to the trophic weight of each of them.

  • The PTIot index, applicable to medium depth lake environments (>-15m) of low and medium altitude (200-800 m a.s.l.), relates the biovolume of each phytoplanktonic species, the trophic index and the indicative tolerance value of that species.

  • MacroIMMI and MTIspecies indexes use the submerged macrophyte community as a bioindicator; they are solely applicable to the Alpine ecoregion’s lakes. These indexes assess the presence of indicator species, weighted by their trophic value and trophic scores in relation to growth depths.

  • The BQI index is based on the composition of the benthic lake fauna, duly considered; it is applicable to any lake context on national territory.

  • The LFI index summarizes the ecological status of lake fishing communities: it is applicable to most Italian lakes.

  • Additional indexes, for example, those resulting from the integration of some of the previous ones (e.g. Phytoplankton Overall Index, ICF), can be determined based on specific customer requirements.

FFI (Fluvial Functioning Index)

The index provides a summary assessment of the fluvial functionality and the causes of its deterioration, as well as precise guidance for redevelopment measures and a prior assessment of their effectiveness. Through the analysis of morphological, structural and biotic parameters of the ecosystem, which are interpreted according to the principles of fluvial ecology, the functions associated with them are detected, as well as the possible deviation from the maximum functionality condition, identified than an ideal reference model. To determine the index, it is necessary to sample the benthic invertebrate communities (see EBI and STAR_ICMi).

ESW (Ecological State of the Watercourse)

ESW defines the ecological status of water bodies’ surface as an expression of the complexity of aquatic ecosystems and the chemical and physical nature of water, considering the status of the biotic elements of the ecosystem as a priority. This index is built up by integrating the results obtained from the application of two sub-indexes and considering the worst result between the two: The Extended Biotic Index (EBI) and the Macro-descriptors Pollution Level (LIM, which provides for the determination of chemical-physical and biological parameters, as referred to in Table 7 of Legislative Decree 152/99 and subsequent amendments and additions).


The CARAVAGGIO Method (Core Assessment of River hAbitat Value and hydromorpholoGIcal cOndition) allows the timely detection of a wide range of hydromorphological and habitat characteristics, fulfilling the requirements of Directive 2000/60/EC; it also provides a qualitative estimate of the extent of the impacts due to the presence of artificial structures and / or anthropic interventions along the waterway axis. The method is however functional to the collection of qualitative-quantitative data at different spatial scales, to be used for conservation, monitoring and/or prevention purposes.

Riparian Areas Quality Indexes (WSI, BSI, ELI)

The proposed indexes are complementary to each other.
They are functional for identification and planning both along a watercourse and in its territory of relevance, in areas with different protection where the development of anthropic activities can be compatible with the reduction of flooding’s risk and with the maintenance of the good status of the river resource.

  • The BSI (Buffer Strip Index) gives an indirect measure of the banks’ ability to filter, metabolize and bioaccumulate the nutrients and pollutants carried in the body of water during floods or percolating from the territory.

  • The WSI (Wild State Index) reflects the natural state of the banks and the potential of these areas to sustain a high level of biodiversity.

  • The ELI (Environmental Landscape Indexes) evaluate the landscape-environment of river areas in its broadest sense (geographical/environmental, historical, perceptive/aesthetic, etc.), so as it is understood by Landscape Planning, depending on the planning of areas, including those with high vulnerabilities.

Ecological Status of Fish Communities

The Ecological Status of the Fish Communities is normally estimated by the NISECI index (formerly ISECI) in the internal water ecosystems among the national territory. The parameter estimates the natural status of the community (calculated on the presence of endemic species expected for the zoogeographic framework of reference, as well as the presence / absence of alien species) and its ecological health’ status (that can be derived from the analysis of dynamics ecological resources, such as the average age of the population and the ability to recruit). Further additions to the method make it possible to adapt the index to the European Water Directives (especially the Water Framework Directive 2000/60/EC), by introducing descriptors of the reference conditions for each water context and the identification of standardized indicator elements.