What is it about?
This study is considered the first in this sector of the Tigris River since 2003 to evaluate the effect of the Tharthar Canal on the composition and diversity of zooplankton in the Tigris River. Six sampling sites were selected; two on the Tharthar canal and four sites along the Tigris River, one before the confluence as a control site and the others downstream the confluence. One hundred thirty-four taxa of zooplankton were recorded in this study, 129 taxa in the Tigris River, 76 taxa in the Tharthar Canal, and 96 taxa shared between the river and canal. The high value of zooplankton density in Tharthar Canal increased the density of the Tigris River from 307989 Ind./m3 in site 1 upstream of the confluence to 371427 Ind./m3 in site 4 immediately downstream of the confluence. Also, the mean values of richness index, evenness index, and diversity index decreased from 7.46, 0.69, and 2.40 bit/Ind. before the confluence to 6.46, 0.61, and 2.08 bit/Ind. after the confluence, respectively. Furthermore, the highest similarity percentage was between sites 1 and 6, reaching 84.28%, while the lowest percentage was between sites 1 and 2 reaching 65.97%. The highest value for the constancy index was 24 at site 6.
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Why is it important?
The study aimed to (1) quantify zooplankton densities in the Tigris River and Tharthar Canal; (2) measure spatial and temporal variations; and (3) measure the impact of the Tharthar Canal on the composition and diversity of zooplankton in Tigris within 2020.
Perspectives
The results indicate that environmental conditions and hydrological regimes were the most important factors that affected zooplankton density. Tharthar Canal reduced the density of rotifera immediately downstream of the confluence and increased cladocera and copepoda densities. The low mean values of species richness index, species evenness index, and Shannon-Wiener diversity index for total zooplankton in Tharthar Canal declined these indices in Tigris River downstream the confluence. In other words, the Tharthar Canal declined the diversity of the Tigris River immediately downstream the confluence. The highest percentage of similarity index for total zooplankton was between sites 1 and 6, whereas the lowest percentage was between sites 1 and 2.
Dr Osama S. Majeed
Ministry of Education, Baghdad, Iraq
Read the Original
This page is a summary of: Effect of AL-Tharthar Canal on the Zooplankton Composition and Diversity in the Tigris River, Al-Mustansiriyah Journal of Science, February 2023, Al-Mustansiriyah Journal of Science,
DOI: 10.23851/mjs.v33i5.1314.
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