Water Quality and Zooplankton Assessment of Iyiakwu River, Southeast Nigeria

Abstract Water quality and zooplankton assessment of a rural river in Southeast Nigeria was carried out between May 2019 and October 2019 in three stations in relation to anthropogenic activities. The major anthropogenic activity in the river was indiscriminate sand mining. The water samples were collected and analyzed using standard sampling and analytical procedures while zooplankton samples were collected using filtration method. pH and dissolved oxygen values were lower than acceptable limits while some of the biochemical oxygen demand values exceeded the acceptable limit. A total of 447 individuals from 25 zooplankton taxa and three major taxonomic groups were recorded. Copepoda was the dominant group (158 individuals/L), followed by Rotifera (147 individuals/L) and Cladocera (142 individuals/L). Spatially, station 1 had the highest abundance (159 individuals/L), followed by station 3 (152 individuals/L) and station 2 (136 individuals/L). The biodiversity indices (Shannon–Weiner and Margalef) were low while Evenness was high when compared with their respective ranges. This study has shown that the combined effects of season, sand mining and other activities have not adversely affected the water quality and zooplankton community. However, the community structure of the zooplankton groups gave an indication of a moderately polluted environment; attributable to the effects of season and human activities in the watershed. Sand mining is a major activity in the river and needs to be regulated to forestall any adverse effect on the water quality and biota in future as observed elsewhere.