Spatio-temporal distribution of zooplankton and physico-chemistry in some rivers of the agricultural area of Awae (Centre Region-Cameroon)

Abstract

In view of conservation of zooplankton in hydro-agricultural environments, a seasonal study was carried out from July 2021 to May 2022, to determine their spatio-temporal distribution in relation to the environmental characteristics of Awae streams (Centre Region-Cameroon). Twelve (12) sampling stations were selected. The water physico-chemical variables were analyse using standard methods, while the zooplankton collected were identified using appropriate references. The physico-chemical results showed that the waters were slightly acidic (6.58±0.02 CU), weakly mineralized (21.89±0.35 µS/cm), moderately oxygenated (58.3±4.48%) and subject to high levels of organic pollution. A total of 70 zooplankton taxa were identified, belonging to 22 families and 44 genera. The Chydoridae family (21 taxa) was the most diverse group. Most of the other taxa were monospecific (Rotifers and Ostracods). Alonella sp. was the only omnipresent species, while Acroperus sp.1, Acroperus sp.2, Chydorus sp. 2 and Kurzia sp. were the only regular species. Despite the low species abundance obtained during the long seasons (dry and rainy), the diversity of species in dry season increased than in rainy season. The results of the correlations between biological and physico-chemical variables showed that temperature, electrical conductivity and organic matter have a strong influence on abundance and taxonomic diversity. This study further confirms the impact of human activities on aquatic environments and their resources.