Zooplankton Composition and Abundance in River Wuye, Abuja, Nigeria

A study of the zooplankton assemblage of River Wuye, Abuja, Nigeria was undertaken from December, 2019 – November, 2020. The aim was to determine the composition and abundance of zooplankton in the river. Water samples for zooplankton analysis were collected monthly from four sampling stations with varying anthropogenic activities along the river from upstream, through midstream to downstream. Thirteen (13) species of zooplankton belonging to three (3) phyla were encountered: Amoebozoa (3 species), Arthropoda/Cladocera (3 species) and Rotifera (7 species) with relative abundance of 52.48%, 2.13% and 45.39%, respectively. The most dominant species encountered was Difflugia accuminata with 41 Organisms/L (29.08%) and the least abundant species were Chydorus alexandrovi, Diaphanosoma sarsi and Moina macrocopa, 0.71%, respectively. Total abundance of zooplankton was 141 Organisms/L. Within the Stations, the highest abundance of zooplankton was encountered in Station 4 (52.48%) and the lowest in Station 3 (11%). The highest monthly abundance occurred in January with 29.79% and the least in July and October with 1.42%, respectively. Seasonal variation in the composition and abundance of zooplankton revealed that Rotifera was dominant in the wet season with 50.75% and Arthropoda (Cladocera) was the least abundant, 4.48%. In the dry season, Amoebozoa (Protozoa) was the most abundant with 59.46% and Arthropoda (Cladocera) was the least with no representation, 0%. Analysis of variance (ANOVA) indicated no significant difference in the values between stations, months and seasons (p>0.05) respectively for Rotifera (p=0.213, 0.120, 0.122) and Arthropoda/Cladocera (p=0.219, 0.020, 0.212). However, ANOVA values showed significant difference (p<0.05) in the values between stations, months and seasons respectively for Amoebozoa (p=0.018, 0.00, 0.026). Shannon-Wiener Species Diversity Index (H’) and Simpson’s Diversity Index values were respectively highest in Station 1 (2.207, 0.8699) and lowest in Station 2 (1.617, 0.7603), with the order of diversity Station 1>4>3>2. The highest value of Margalef‘s Richness Index was 3.04 in Station 3 and the lowest, 1.618 in Station 2 (order for richness, Station 3>1>4>2). Pearson’s Correlation showed several significant positive relationships between zooplankton species and a few inverse relationships. Effective monitoring of the river and control of anthropogenic activities with community enlightenment are recommended; as well as further work on the interaction between zooplankton and environmental variables (physicochemical parameters) towards quality enhancement, productivity and sustainability of the freshwater resource.