The effect of some environmental factors on the abundance and distribution of annelid worms from Shatt Al-Arab, Basra, southern Iraq

The present study aims at diagnosing the species of Annelida in sediment Shatt Al-Arab and studying their density. period sample collection starts from January 2021 up to May 2021. Nine stations lying on Basrah district were chosen starting Qurna station northward Al-Fao southward. included measuring some environmental factors water sediments.
 Water temperature ranged between 9-19, 7.2-8.6 for pH, 5.8-9.1 Mg/ltr dissolved oxygen, 2.1-29.5 ppt salinity concentrations. In sediments, percentage TOC was 0.25-1.03 %. Three diagnosed stations, two them belong Namalycastis indica, Dendronereides heteropoda. third belongs Limnodrilus hoffmeisteri.
 density during recorded. It 1550-3709 individual/m2 Polychaeta while L. hoffmeisteri, 2159-8885 individual/m2. distribution into longitudinal classes studied it recorded least appearance rates D. heteropda 40-50 mm class most highest 1-10mm a number stations. N. indica has however, 30-40 four For hoffmeisteri species, rate 18-21 3-6mm many stations.
 statistical analysis showed that temperature, are directly related both oxygen is (r=0.470) inversely with (r=-0.094).