Zooplankton of Basrah district, Southern Iraq

Abstract

Monthly samples were collected from seven stations at Basrah city by a plankton net (0.090 mm mesh- size and 40 cm mouth aperture) from November 1995 to December 1996 at stations 3, 4, 7 (St.3 is a small pool at the university campus, Garmat-Ali ; St.4 Al-Maqal creek, a small creek connected to Shatt Al-Arab River ; St.7 Abdulyan creek in Abi-Al-Khasib, South of Basrah) and from December 1995 to May 1996 at station 5 and from June 1996 to May 1997 at stations 1, 2, 6. The population density of zooplankton ranged between 110 ind/m3 during August 1996 at sta. 1 to 1769250 ind/m3 during April 1996 at sta. 5. Copepoda constitute 36.8 % of the total zooplankton. The second important group was Rotifera (33.7 %), then Ostracoda (10.7 %), whereas Cladocera came fourth (8.8 %) followed by the cirripede larvae (4 %). Biomass of zooplankton estimated as wet weight, it ranged from 0.5 mg/m3 during June 1997 at sta. 6 to 67241 mg/m3 during March 1996 at sta. 5. The biomass in terms of dry weight, ranged from 1.028 mg/m3 during July 1996 at sta. 4 to 21929 mg/m3 during March 1996 at sta. 5 and in terms of displacement volume and standing crop, the biomass ranged between 0.028 ml/m3 and 1.820 mg C/ m3 during June 1996 at sta. 4 and 88.6 ml/ m3 and 5757 mg C/ m3 during April 1996 at sta. 5, respectively.