Ecological Study of Zooplankton in South Shatt Al-Arab River, Southern Iraq

The ecology of zooplankton in general and Copepoda in particular has been studied in this study. The samples were collected monthly, during the period from December 2011 to November 2012, in south Shatt Al-Arab River at Al-Siba and Al-Faw by using plankton net of 85 μm mesh sized and a mouth aperture of 30 cm, by vertical collection method. Physical and chemical parameters were studied such as: water temperatures were ranging from (13 – 28 °C), pH values (7 – 8.8), the salinity (0.5 – 41.5‰) in station 1 and 2 respectively. The highest oxygen concentration (12 mg/l) was recorded at station 2 during December 2011, whereas the lowest concentration was (6 mg/l) at station 1 during August 2012. The highest value of chlorophyll – a was (19.9 mg/m3) at station 2 during November 2012, while the lowest value was (2.8 mg/mᶟ) at station 1 during December 2011. The highest density of zooplankton reached (53211 ind./mᶟ) at station 2 during May 2012, whereas the lowest density was (21 ind./mᶟ) at station 1 during December 2011, where the highest density of copepods was (48966 ind./mᶟ) at station 2 during May 2012, and the lowest density was (7 ind./mᶟ) at station 1 during December 2011. Fifty-three taxa of zooplankton were identified through the present study, 34 taxa belong to Copepoda, and 19 taxa belong to the other zooplankton. Copepoda dominated among the other zooplankton. The species Acartia (Odontacartia) ohtsukai was new record in Iraqi water.