Jonah, U.E. (2025). Appraising the Seasonal Variability of Zooplankton Assemblages in Lotic Freshwater Body: Upper Segment of Qua Iboe River, Akwa Ibom State, Nigeria. Ceylon Journal of Science. 54(3):715-726.

513431

10.4038/cjs.v54i3.8646 [view]

Jonah, U.E.

2025

54(3):715-726.

Publication

Available for editors  

This study was carried out in the upper segment of Qua Iboe River, Niger Delta, Nigeria between January 2020 and June 2021 in five sampling locations (between Ikot Amba to NkekIdim) of about 23.3 km, to ascertain the seasonal dynamics of zooplankton and physicochemical properties of the study area. Zooplankton samples were collected by towing a plankton net with 55 µm mesh through a 120 m stretch of a water column, for ten minutes. The concentrated zooplankton samples on the towing net were filtered into 1 L sampling bottles and were fixed with two drops of 4% formalin solution. Zooplanktons were identified to the most possible taxon under the light microscope, and enumeration was carried out using a Sedgewick rafter counting chamber. Water samples were collected from the river, using 1 L plastic bottles and transferred with ice chests to the laboratory for further analysis. Parameters such as water temperature (WT), electrical conductivity (EC), dissolved oxygen (DO) and total dissolved solids (TDS) were measured in-situ while ammonia (NH3) , chemical oxygen demand (COD), total hardness (TH), total suspended solids (TSS), total alkalinity (TA) and calcium (Ca 2+ ) were measured ex-situ. The mean concentration of NH 3 in dry (0.49±0.03) and wet season (0.56±0.03), COD in dry (101.16±6.38) and wet season (138.02±5.38), and TSS in dry (48.33±2.44) and wet season (68.65±2.41) were exceeded the limits for aquatic life while DO value (4.40±0.16) in the wet season was below acceptable limit. A total of 1806 individual zooplankton was recorded in dry season while 1495 was in wet season. Rotifers were slightly less abundant during the dry season while Protozoans, Copepoda and Cladocera were more abundant during the dry season. There was a significant variation in all the parameters except for NH3 , Ca 2+ concentrations and zooplankton abundance (p < 0.05) between seasons. Parameters such as COD, TSS and NH 3, negatively influenced the abundance of zooplankton in wet season, in conjunction with anthropogenic activities and surface runoff.

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