Spatial and temporal of Oligochaeta fauna in Sardabroud estuary of Chalus (South Caspian Sea)

Oligochaete species composition closely reflects the aquatic environment in which they live; they are good indicators of water pollution, climate change and water sources classification. In order to study of biodiversity and distribution of the Oligochaeta fauna and their relationship with environmental factors in Sardabroud estuary of Chalus (South Caspian Sea basin), bimonthly Samples were taken from November ۲۰۱۴ to September ۲۰۱۵, in three stations (S۱ in the river environment, S۲ in estuary environment and S۳ in the marine environment), using Van Veen grab (۰.۰۳ m۲) and Surber (۰.۱ m۲, ۰.۲ mm-mesh size) with three replicates. In the present study, three families were identified, including Naididae (۳ species), Tubificidae (۷ species) and Lumbriculidae (۳ species). ۹ species were reported from the river and estuary of Sardabroud for the first time. Among identified species, the highest and lowest average densities were related to Stylodrilus cernosvitovi (۶۲۲.۲ ind. m-۲) and Stylodrilus hyrringianus (۱۱.۱ ind. m-۲), respectively. Results of monthly distribution showed that the highest and lowest densities of Oligochaeta fauna were in July (۳۴۹.۳±۱۱۲ ind. m-۲) and in November (۱۸۰.۲±۶۶ ind. m-۲) respectively which were significantly different, by Duncan's test (p<۰.۰۵). Among sampling stations, marine station (S۳) showed higher density (۲۸۴.۶±۹۶ ind. m-۲) than river station (S۱) (۱۵۷.۱±۴۹ ind. m-۲) and estuary station (S۲) (۳۵.۷±۸.۴ ind. m-۲) which were significantly different (p<۰.۰۵).

Keywords:

Identification , Density , Distribution , Oligochaeta , Sardabroud estuary , Caspian Sea