CNR-IRSA activities related to INHABIT

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STAR_ICMi

STAR_ICMi has been derived as tool for the Intercalibration related to macroinvertebrates’ community in rivers. The index has been developed within EU co-funded STAR Project ("Standardization of river classifications: Framework method for calibrating different biological survey results against ecological quality classifications to be developed for the Water Framework Directive"). STAR Projects partners have provided technical support on Intercalibration upon request by JRC (Joint Research Centre, Ispra) and EU DG Environment.

At present STAR_ICMi is in use in Italy and other countries in order to:

  1. provide a classification method for ecological quality in streams;
  2. provide an official method for defining class boundaries for all the methods that will be developed ore applied for the Intercalibration exercise.

The index is not intended to be stressor specific, indeed it has been developed to assess general degradation in river sites. It is directly expressed as Ecological Quality Ratio (EQR) and its value varies between 0 and 1+. The index provides a classification result fully compliant with WFD requests.

STAR_ICMi is a multimetric index that includes 6 normalized and weighted metrics. The 6 metrics are: ASPT, Log10(sel_EPTD+1), 1-GOLD, Number of EPT families, Total number of families and   Shannon-Weiner diversity index. Such metrics consider the main features related to the benthic community requested by WFD. Requested identification level is family. Some of the metrics require information about abundance of collected taxa.

The calculation of the STAR_ICMi is performed in 4 steps:

  1. calculation of the raw value for each of the 6 metrics;
  2. calculation of the EQR value for each of the 6 metrics by dividing the observed value (i.e. obtained for the considered samples) by the median value of the metric calculated on the reference samples of the considered river type;
  3. calculation of the weighted average of the EQR considering the weight assigned to each metric;
  4. normalization of the obtained value by dividing the value of the considered sample by the STAR_ICMi expected in reference samples.

In step 2 for ASPT the value of 2 must be subtracted from the observed value before EQR conversion. This because values less than 2 have been observed only very seldom for ASPT. Whether a value less than two will be observed the value of 0 will be used as EQR.