Abundance and diversity of zooplankton in the Tigris River Northern of Basrah, Iraq

Abstract

Seasonally variations of the quality and quantity of zooplankton were studied in two stations in the terminal sector of Tigris River and one station at the confluence of the Tigris and Euphrates area, in Al-Qurnah North of Basrah City, during October 2015 to August 2016. Samples of zooplankton were collected by plankton net (100µm. Mesh size). Salinity changed from 1% at St. 2 to 1.8% at St. 3, the pH varied from 7.5–8.2 and the dissolved oxygen from 6mg/l to 8.7 mg/l at St. 3 and St. 1 respectively. In study area the population density of zooplankton ranged between 20.3ind./m³ during Autumn and 243.41ind./m³ during Winter at station 1 (Al-Jewaber Bridge). The results showed that the Crustaceans were the dominated group that comprised 92.9%, 93.1% and 98.1% in study area respectively. Copepoda were the dominant in three stations, which constituted about 43.8% followed by Cladocera 35.2%, Cirripede larvae 7.2%, and Zoea of shrimp 4.2 % of the total zooplankton respectively. Maximum richness (D) of (1.66) was obtained at station 1 during summer and autumn and higher Diversity (H) of (1.41) was recorded at station 1 during spring, while higher evenness (J) of (0.70) was obtained at station 2 during summer. The Jaccard׳s index values were close and revealed a higher similarity between stations 1 and 2, and lower values between stations 1 and 3.