The ecology of Rotifera of the Shatt Al-Arab region was studied at five stations: Khalid Birdge (1), Basrah Silo (2), Tanoma Bridge (3), Khirtrad creek (4) and a pond near the College of Engineering (5). Monthly vertical hauls were taken by 50 μm plankton net from near the bottom to the water surface during February 2007 to March 2008. Density of zooplankton fluctuated between 1.36 and 836.31 ind./L. Maximum density was at station 5 and the minimum was at station 1. Rotifera dominated the zooplankton at all stations, ranging from 1.09 to 650.99 ind./L at stations 1 and 5 , respectively. Peak density of Rotifera was recorded at station 5 which is the highest value ever recorded from any aquatic habitat at Southern Iraqi wetlands. Ninety nine species of Rotifera belonging to 23 genera and 15 families were encountered. Synchaeta lakowitziana and Bdelloidea were the most dominant groups at all stations during the study period. The ecological indices measured were: richness (1.32- 8.43), Shannon-Weaver diversity index (0.99-2.36), evenness (0.59-0.91) and similarity index. The highest value of diversity was recorded at station 5. The highest similarity index (35.54) was between stations 1 and 2, while the lowest value (20.66) was between stations 4 and 5. Positive correlations were found between density of Rotifera and water temperature, total solids, chlorophyll a and phytoplankton. Significant differences were occurred between most of the ecological factors at different stations. Associations between Rotifera assemblages and environmental variables were quantified by using Canonical Correspondence Analysis (CCA), indicating a correspondence of the correlation values with those calculated by usual methods.
Naeem Shanad Hammadi, Salman Dawood Salman, Salih Abdul-Qadir Al-Essa