The Department of Biology discussed a master’s thesis entitled “The Impact of the Diyala Tributary on Rotifer Diversity (Zooplankton) in the Southern Section of the Tigris River in Baghdad City”, presented by Rand Raad Ahmed under the supervision of Assistant Professor Dr. Intisar Faisal Abd.
The examination committee consisted of:
Prof. Nibras Lafta Abdulqader.
Assistant Professor Dr. Ruaa Jaafar Hameed.
Chief Researcher Dr. Muhannad Ramzi Nishat.
Assistant Professor Dr. Intisar Faisal Abd.
The study aimed to assess the influence of the Diyala River on the biodiversity of rotifers (zooplankton) in the Tigris River by identifying the physical, chemical, and biological characteristics of the river water before and after the confluence with the Diyala tributary. The research also investigated the quantitative and qualitative composition of rotifers in both the Tigris and Diyala rivers and applied selected biodiversity indices to evaluate ecological variations within the study area.
The findings highlight the importance of generating scientific data that contribute to understanding the relationship between water quality and aquatic biodiversity. Such knowledge supports environmental protection efforts, promotes the sustainable management of water resources in Iraq, and strengthens ecological studies concerned with biodiversity conservation and biological indicators of water quality.
This research contributes to the achievement of several United Nations Sustainable Development Goals (SDGs), particularly SDG 6: Clean Water and Sanitation, by supporting sustainable water resource management and water quality monitoring, and SDG 14: Life Below Water, through enhancing the protection of aquatic ecosystems and conserving biodiversity in river environments.
The present study has encompassed numerous biological factors such as total rotifer density, Relative Abundance Index (Ra), Constancy Index (C), Species Richness Index (D), Shannon–Wiener Diversity Index (H), Species Evenness Index (E), and Jaccard Similarity Index (J). Data were analyzed using the (SAS) statistical program and correlation coefficients were determined among the studied variables. The analyses revealed strong correlations between air and water temperatures across all sites with air temperatures in the range of 12–43°C and water temperature in the range of 13.2–31.5°C.
Electrical conductivity values ranged from 666 to 3720 µS/cm, while salinity values ranged from 0.43 to 3.38%, indicating that the water in the river is slightly to moderately saline, depending on the sites in question. The water was slightly alkaline, with pH values of 6.8–8.1, and moderately well-oxygenated in terms of dissolved oxygen, ranging from 1 to 11 mg/L. On the other hand, elevated biochemical oxygen demand values (0.8–78.2 mg/L) indicate that the Diyala River is polluted according to standard BOD values. Turbidity values ranged from 0 to 42.40 NTU.
Total hardness showed elevated levels at certain sites, ranging from 195 to 800 mg/L. Calcium ion concentrations measured between 52.1 and 320.64 mg/L. Magnesium ion concentrations ranged from 108.76 mg/L to 662.48 mg/L, which were higher than the permissible limits of both calcium (200 mg/L) and magnesium (150 mg/L) according to the guidelines for natural waters. Total alkalinity ranged from 0.1 to 6.5 mg/L, nitrate ranged from 0.036 to 3.23 mg/L, and the limits according to the Iraqi River Conservation System (2001) is 15 mg/L, while phosphate ranged between 0.010 to 0.1178 mg/L. Additionally, total dissolved solids (0.88-3.51 mg/L) and total suspended solids (0.008-37.00 mg/L) also differed from site to site.
We identified a total of 81 rotifer taxa. The range for total density of rotifers was from 25 to 55,866.59 individuals/m³. The Relative Abundance index shows that Keratella quadrata (long spin), Monostyla bulla, Brachionus angularis, and B. calyciflorus calyciflorus were the most recorded species because of their high tolerance to environmental stress.
The Constancy Index showed that the commonest and most significant species were Brachionus angularis, B. calyciflorus, B. plicatilis, B. urceolaris, Keratella cochlearis, K. quadrata (long spin), Monfredium eudactylotura, K. valga, Euchlanis dilatata, Monostyla bulla, Polyarthra dolichoptera, R. neptunia, and Synchaeta oblonga. The rest of the taxa were classified as accessory and accidental species depending on their presence across the sampling sites.
The values for the Species Richness Index (D) were from 0 to 6.179327, with the peak in spring and the minimum in summer. The Shannon–Wiener Diversity Index (H) varied from 0 to 2.490986 bits/individual, with the greatest diversity in winter and the least in summer. The Species Evenness Index (E) was from 0 to 1, indicating environmental pressure on the rotifer communities in the river’s ecosystem.
