Environmental effects of Lower Zab tributary on benthic invertebrates species diversity in Tigris River

الملخص EN

Benthic invertebrates' diversity and some physical and chcmical characteristics in Lower Zab tributary and Tigris River were studied.

Monthly samples were collected from November 2001 to Octohcr 2002.

The results of آل1ا present study showed tl،e turbidity in Tigris river before the confluence to be higher (34.4 .٧٢٧) compared to the other stations.

Mean salinity was greater ١٦؛ Lower Zab tributary (0.33 u/o) compared to that ١٦؛ the river.

Lower Zab tributary and Tigris River were good أل؛ Oxygen content, ؛md a high dissolved oxygen value was recorded (7.9 آء؛ ١^١١١ Lower Zab tributary.

31 benthic invertebrate species were identified, 14 of whieh were arthropods, 8 species from both of the Oligochacta and .Mollusca .One single species was identified from the Nemathelminthes.

Species diversity varied from 1.9 in Lower Zab tributary to 2.7 هإ Tigris River after the conlluence.

The highest spccics density was recorded in Tigris River after the conlluence was 359.1 ind/m while the lowest species density was 12.74 ind/m2 in Lower Zab tributary.s