Principles to develop a simplified multimetric index for the assessment of the ecological status of Armenian rivers on example of the Arpa River system.

The Government of the Republic of Armenia (RA) strives to ensure the measures to achieve good ecological status for Armenian surface water bodies. However, the main goal remains unaccomplished, as the hydro-biological monitoring tools are not properly developed. Thus, the current work aims at contributing to the establishment of principles and a relevant and cost-effective biological monitoring tool for the RA aquatic ecosystems, through the development of a simplified multimetric index (MMI). Since the adoption of the decree N° 927-N from 11 Jun 2011, the baseline studies have been initiated in the six river basin management areas established in the RA. The current work is summing up the results for the Arpa River system in order to test the methodology. In particular, it is testing the possibility to develop MMI based on the use of Rapid Biological Assessment protocol accepted in our monitoring system. Also, the work represents the approach of bottom-up biotic validation of reference sites established in the recent hydro-biologic monitoring system. Due to the proposed validation procedure, further use of one of the established reference sites in the case study object has been rejected. Considering well-established approaches for MMI development in EU member states, four variations of MMI were developed for a particular river system, and the combination of Ntaxa -%EPT-Abundance(ind/m2 )-BMWP-ASPT-FBI-Nfamily metrics has been proposed as the main one. However, further development of a river typology and the establishment of joint reference conditions in the Caucasus region have concluded as a priority.