Environmental Study of the Benthic Mollusks in Euphrates River at Samawa City, Iraq

A study of the physico-chemical parameters on surface water of Euphrates River at Samawa, South Iraq, was conducted from October, 2012 to September 2013. Surface water was collected from three different stations along the river. The results were revealed that the values of air temperatures ranged between 15- 42 C; water temperatures 15- 30 C. The pH was showed slightly alkaline trend. Electrical conductivity was ranged 3000-9000 S/cm, Salinity values were ranged between 1.92- 5.76, according to the classification of Reid indicated that station waters were Oligosaline during the study period. The total dissolved solids showed values ranging from 1400-6200 mg/L. Dissolved oxygen showed maximum values in winter season. However the results were showed that river water is very hard, the total hardness, Ca hardness& Mg were ranged 600-1350, 300-950, and 48.6-219.91 mg CaCO3/L, respectively. Turbidity was ranged 12.8- 130 NTU. Monthly and seasonal fluctuations in densities of freshwater Mollusca were recorded during study period. The study revealed the occurrence of 5 species of freshwater Mollusca belonging to 5 families of class Bivalva& Gastropoda. These species are: Corbicula fluminea, Unio tigridis, Melanoides tuberculate, Melanopsis nodosa and Viviparus bengalensis. The densities of the recorded Individuals varied seasonally and the general seasonal peak was recorded during Spring while the lowest density observed during Winter. Statistically, significant differences were recorded in the water parameters values and Mollusca density (P 0.05) during study months, while there have been no significant differences between stations.