Study of the Aquatic Oligochaetes Community in Tigris River Sediment, Baghdad Iraq

The present investigation is concerned with study the community structure of aquatic oligochaetes collected fromTigris River sediment in three sites within Baghdad province Including site (S1),is located north of Baghdad, at A- Rashydia district, site (S2) is located in middle at Al- Sarafiya District, , while the third site (S3) is located south Baghdad at Al-Za'afaraniya district. for the period from December 2018 to November 2019. A total of 1999 individual represented 13 species were sorted, seven species of them belonging to the subfamily Tubificinae , two species to the subfamily Rhyacodrillinae, two species to the subfamily Naidinae , in addition to one species of each of subfamily pristininae, and family Enchytraeidae). The result revealed presence of Embolocephalus velutinus (Grube,1879) and Limnodrilus maumeensis (Brinkhurst and Cook,1901), which are considered as new records for Tigris River fauna.. According to the Relative abundance Limnodrilus spp specially L. hoffmesisteri in all study sites. Temporally , the most species richness was recorded during Limnodrilus species were record.