THE EFFECT OF AL-THARTHAR-EUPHRATES CANAL ON THE QUANTITATIVE AND QUALITATIVE COMPOSITION OF ZOOPLANKTON IN EUPHRATES RIVER

Four stations were selected to carry out this study. Two stations were located at Al-ThartharEuphrates canal, while the remaining two were located at Euphrates River, to know the effect of Al-Tharthar-Euphrates canal on the composition and diversity of zooplankton in Euphrates River. In all the studied stations the total zooplankton showed high densities in autumn and low densities in summer. The statistical analysis results showed significant difference between station 3 and station 4 in Euphrates River. Rotifera were the dominant group quantitatively, followed by Copepoda and Cladocera. 52 taxa of zooplankton were recorded, 32 taxa belonged to Rotifera, 12 to the Cladocera and 7 to the Copepoda. The results also showed that the Rotifera: Keratella cochlearis and Brachionus calyciflours, the Cladocera: Bosmina longirostris, the Copepoda: nauplii were dominant in both canal and Euphrates River. The biodiversity indices indicated high fluctuated with seasons. The results also showed that the species composition in the Euphrates river were not affected by the canal water. The higher values of uniformity index of different zooplankton groups indicate there is no ecological stress on zooplankton in the study area. Introduction The zooplankton groups are considered as characteristic indicator of water quality, eutrophication and pollution levels [1,2]. The total zooplankton abundance and diversity vary according to limnological features and trophic state [3]. In Iraq numerous studies were achieved [4,5,6,7,8,9]. These studies showed that the Rotifera was the dominant group quantitatively and qualitatively in most of Iraqi inland water. The aim of the present work is to study the effect of Al-Tharthar-Euphrates canal on the composition, community structure, biodiversity and abundance of zooplankton in Euphrates River in study area. Materials and methods Study site The total length of the Euphrates River is 2940 km, from that 1159 km, inside Iraq. It has no tributaries inside Iraq except for few valleys which aggregate water during the rainy season [10]. The canal of Al-ThartharEuphrates is considered one of the important parts of Al-Tharthar lake project, it was established in 1976 to connect the lake (which receives its water from Tigris River) to Euphrates River, with total length reaches to 37 km, and maximum discharge (500 m/sec.), while the working discharge ranged between 10-200 m/sec. Four stations were selected to carry out the present study. Two stations were located at Al-Tharthar-Euphrates canal, and the other two were located at Euphrates River. One of them was located in the area before the connection of this canal with Euphrates River as a control station, and the other one was located after the confluence of the canal to evaluate the ecological effects of this canal by comparison with the control station (Fig.(1)). Samples collection Seasonally subsurface samples were taken during 2009 from the selected stations. Sampling was performed 4 times, in winter (February), in spring (April), in summer (July), and autumn (October) in 2009. Water temperature, electrical conductivity, TDS and pH were measured in the field using Multimeter HANNA Model (HI 9811-5). While dissolved oxygen was determined following Mackareth et al [11]. The zooplankton samples were collected with a standard plankton net (25 cm diameter and 55 μm mesh size) by passing 60 litter from station water. All specimens preserved in 4% formalin. The samples were divided into subsamples (1ml) with a pipette and counted.