MTS - Mayfly Total Score

CNR-IRSA activities related to INHABIT

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MTS - Mayfly Total Score

For deriving Ecological Status based on benthic invertebrates, the assessment of environmental quality by means of the MacrOper system in large and/or non wadable rivers and streams in Italy includes the metric MTS (Mayfly Total Score). This metric is then combined with the STAR_ICMi.

Calculation of MTS requires the identification of mayflies community to Operational Unit (OU) taxonomic level, corresponding to genus for most of the taxa and to a slightly more detailed level in a few cases. OUs are groups of taxa of a defined identification level based on taxonomical, morphological or ecological similarities among species of mayflies. To each OU a fixed score is given: 1 to taxa relatively tolerant or present in a wide range of environmental conditions; 3 to taxa presenting no particular indicator value (due e.g. to problems related to life cycle, ecology, distribution, etc.); 5 to OUs known to be indicator of 'good environmental quality' (from several points of view, in particular related to habitat quality). For a given site, the MTS (Mayfly Total Score) is calculated as sum of the individual scores related to the OUs found in the river. When MTS is calculated to support Ecological Status classification, the EQR value is obtained by dividing the observed MTS value by the  MTS value expected in reference conditions (DM 260/2010).

Scores of the single OUs will be in the short reported on this web site.