TAXONOMIC STUDY OF CHIRONOMIDAE (DIPTERA) LARVAE OF ZAYANDEHROOD RIVER, IRAN, AND EFFECTS OF SELECTED ECOLOGICAL FACTORS ON THEIR ABUNDANCE AND DISTRIBUTION

To date, no comprehensive study has been carried out on the chironomid larval identification in running waters of the country, in particular in large rivers. Therefore, this article is the first of its kind in Iran that has come out in English. Samples were collected in 9 sites from the Zayandehrood River a distance of 230 Km down the Zayandehrood dam. The sampling was repeated four times: November 1998, February, May and August 1999. The samples were hand sorted in the laboratory and the larvae were identified to generic level, using available identification keys. To study the effects of sites and seasons, and selected ecological factors on chironomid larval abundance and distribution, data were analysed using a two way ANOVA. Twenty seven genera were identified in three subfamilies including 14 in Chironominae, 9 in Orthocladiinae and 4 in Tanypodinae, from which 20 genera are reported from the Zayandehrood River, Iran, for the first time. The results also revealed that the mean number of the larvae was significantly different according to sites (P < 0.001) and seasons (P < 0.001). The velocity, depth and substrate showed no significant effects on the larval abundance, but vegetation cover did, significantly.

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