Development of a multimetric index based on benthic macroinvertebrates for downstream Jajrud in Tehran province, Iran

Abstract

Jajrud River is the main source of drinking water in the East of Tehran. The river originates from heights of the Alborz Mountain in Northern Tehran. In this study, five stations were sampled for water quality assessment in downstream. Brgjhan and Afjeh stations were considered as reference stations. Benthic macroinvertebrate sampling was repeated 3 times at each station with a Surber sampler device and an area of 900 square cm and a mesh size of 250 microns, in four seasons. For the development of MMIDJ (Multimetric Macro-invertebrate Index Downstream Jajrud-MMIDJ) multimetric index based on benthic macro-invertebrate, 25 bio-indicators were compared in the reference stations with the data of two years, 2013 and 2014. The features of the bio-indicators included measurement of components tolerance, composition, richness, and trophic. MMIDJ multimetric index was developed from 6 indices including HFBI (Hilsenhoff Family Biotic Index), BMWP/ASPT (Biological Monitoring Working Party/Average Score per Taxon), NJIS (New Jersey Impairment Score), MMIF (Multimetric Macro-invertebrate Index Flanders), % Ephemeroptera, and BBI (Belgian Biotic Index). Indices selected were significantly correlated with at least one physicochemical parameter and low degree of changes like % Chironomidae, % non-insects, the ratio of EPT (Ephemeroptera, Plecoptera, and Trichoptera) individuals to Chironomidae, and high density. Water quality in MMIDJ multimetric index was classified into four. Index values were from 6 to 30. The water quality improved from 6 to 30. With regard to water quality assessment of Jajrud River using MMIDJ multimetric index, Jajrud River did not have a good quality. Appropriate management actions should be considered in Jajrud River for improvement of the water quality.