Seasonal Dynamics of Zooplankton Assemblages in Relation to Physicochemical Characteristics of River Rima, Sokoto State, Nigeria

Abstract

This study was conducted in Kwalkwalwa area of River Rima Sokoto, Sokoto state, Nigeria. It aimed at assessing abundance of zooplankton and its relationships with some physico-chemical parameters. Three sampling stations were identified as station A (shoreline site), B (Fishing activities area) and C (Farming and irrigation site). The sampling was carried out monthly, between April 2018 to March 2019. The mean average of seasonal physico chemical parameters were, DO (4.41 mg /L), water temperature (27.03 ⁰C), pH (6.83), TDS (6.0 mg/L), Turbidity (19.58 cm)), EC (127.05 μS/cm), phosphate (0.19mg/L) and nitrate (1.01 mg/L).  The difference in physicochemical parameters between the three stations of the river was not significant except for turbidity, where there were significant (P<0.05) differences between stations B (20.39) and C (25.71). Nine species of zooplankton were discovered which includes 2 species of each from Rotifera and Cladocera and 5 species of Copepoda. The percentage relative abundance of each zooplankton groups from all the seasons recorded was in the following order, Copepods > Rotifers > Cladocerans. Further studies are warranted on the continuous monitoring of this water body to know the future impact of climate change on distribution of zooplankton which can help to identify the sensitive and sentinel species to formulate the effective conservation strategies.