Abundance and diversity of mollusks and related to some physicochemical properties in euphrates river in Al-Muthanna province

Study was conducted to identify the composition of mollusks in relation to some physical-chemical parameters of the Euphrates river during the period from November 2019 to October 2020. The water temperature ranged between 11.33-38.67 °C. The highest mean of electrical conductivity was 3026.6μS/cm, whereas the lowest was 1203.3 μS/cm. The maximum TDS was 2766.6 mg/l. The water flow was ranged from 0.133 to 0.426 m/sec.The turbidity ranged between 11.59 and 134.63NTU. TSS recorded the highest mean of 36.66 mg/l and lowest of 21 mg/l. The pH values ranged between 6.63-8.60 and the concentrations of DO and BOD5 between 5.15-10.10 and 1-12.33 mg/l, respectively. TA, TH, Ca+2, and Mg⁺² were within 131.33-181.66, 423.33-1386.6, 125-320 mg. The NO2^-2 , NO3^-1 and PO4^-3 varied between (0.03-3.05, 0.053-6.890 and 0.06-0.77 μg l^-1;, respectively). The TOC ranged between 0.055-3.12 % and type of texture was silty in all stations. The study revealed the occurrence of 6 species of Mollusks with total density of 242.84 Ind./m²- The relative abundance index, showed that thespecies M. nodosa was dominant and C. fluminalis less abundant. The Shannon-Weiner and Simson diversity indices ranged between 0.39-2.95 and 0.1-0.93, respectively.