Macro-benthic population structure in Neor Lake, Ardebil province

Macro-invertebrates play a key role in freshwater lentic and lotic ecosystems. Lake Neor is located in northwest of Iran, southeast of Ardebil city, 2480m above the sea level. Limnological data about lake is incomplete. This tectonic lake is known to have a unique macro-invertebrate fauna. In order to describe the zoo-benthic community of the lake more completely, the present study was conducted during a period of one year from August 2008 to July 2009 with the exception of 3 months during the 5 months the lake is covered by ice. The benthic assemblage was sampled monthly from four sites and these fauna were found to be very limited with a total of 11 species belonging to 10 families, 10 orders, 7 classes and 3 phyla. Eight species were identified and recorded for the first time in the lake and in Iran. Gammarus fasciatus, Pisidium supinum and Quistadrilus multisetosus were the dominant benthic species representing more than 49, 43 and 5 percent of the total benthic fauna. Almost all benthic species showed the same intra-annual, seasonal and spatial pattern. The highest density was found in station 4, near the outlet, in July. The maximum abundance of total population of macro-benthoses in Neor lake was composed of 41872.75 pieces in a sample per square meter in September and the minimum with 28177.08 pieces in March. Dissolved oxygen, temperature and habitat homogeneity seemed to be the main environmental factors affecting community indices in Lake Neor.