Background: This research considered the first of its kind in this sector of the river for more than three decades, aimed to evaluate the diversity, abundance, richness and spatiotemporal variations of zooplankton within Samarra Reservoir water during 2023. Methods: Three sampling sites were selected for this study. Results: A total of ninety-three species were identified: fifty-seven species of Rotifera, nineteen species of Cladocera, and seventeen species of Copepoda. The total density varied seasonally and spatially, ranged between 1099.1 ind./m3 in site 2 and 168818.98 ind./m3 in site 3. Analysis of ecological indices shows that the Samarra Reservoir is rich in zooplankton variety, with diverse and homogenized species. Furthermore, the similarity analysis indicated the highest value (67.94%) between the species in site 1 and site 3. In contrast, the largest difference in species composition recorded between sites 2 and 3 was 12.34%. Conclusion: The study highlights the richness and stability of zooplankton communities in Samarra Reservoir, with rotifers as the dominant group. Spatial and temporal variations in diversity and abundance suggest their potential as biological indicators of environmental change.
Majeed et al. (2025) studied this question.