Introduction of Chironomidae larvae and study of some effective agents on their abundance in Golpaygan River

The family Chironomidae (non- biting midges) is a group of insects belonging to the order Diptera. Most of them spend their larval stage in water. The Chironomidae is frequently the most abundant benthic fauna in a majority of aquatic ecosystems. The Chironomidae has a wordwide distribution owing to its broad ecological tolerances. The larvae species composition closely reflects the aquatic environment in which they live, as a result, they are good indicators of water pollution, climate change and lake classification. They also play a considerable role in the organic matter processing and the food chains of water communities. Considering the importance of family Chironomidae in aquatic habitats, this information can be used in ecological and taxonomical studies. The present study was conducted in Golpaygan River located in province Isfahan. Five stations were selected on the river and six time of sampling were conducted from July 2003 up to June 2004. After sampling, chironomid larvae were sorted out, counted and kept in preserving solution. They were made in to fixed slides using phase contrast microscope and the available identification keys which are accordance with the morphological characteristics of the larvae, were identified to genus level. The results showed the presence of four subfamilies and 33 genera. There was found a significant effect of season, station, substrate, dissolved oxygen, temperature, current velocity and EC on abundance of chironomidae using the Co-variance analysis.