taxonomy of benthic macroinvertebrates in jajrud river for water quality assessment

The invertebrates are one of the most important terrestrial fauna and freshwater taxa. benthic macroinvertebrates include aquatic insects and spiders, mites, crustaceans, and species of mollusks and worms that are aquatic in their immature stages and terrestrial in their adult stage. jajrud river originates from the alborz mountains and is a source of drinking water for people in eastern part of tehran and the surrounding villages. for the taxonomic identification of benthic macroinvertebrates, five stations downstream of jajrud were used. a surber sampler device was used for sampling with dimensions 30 × 30 cm and mesh size of 250 microns in all four seasons of the year 2013 with three repetitions at each station. in total, five orders (ephemeroptera, coleoptera, diptera, trichoptera, and oligochaeta) and 13 families of benthic macroinvertebrates were identified. in all stations, the family baetidae (baetis sp.) belonging to the order ephemeroptera had the highest abundance, and seasonally the highest abundance was detected in autumn, winter, summer, and spring respectively. after the identification of benthic macroinvertebrates, five biotic indices including ept, hfbi, signal, njis, and mmif were calculated for water quality assessment in downstream of the jajrud river. regarding the results of the biotic indices, it can be said that the water quality of downstream of jajrud river is not favorable. therefore, appropriate management measures should be taken to improve river water quality.