Specific diversity and abundance of communities of microcrustaceans and rotifers in two ponds, Mokolo and Mopa in the city of (Bertoua, Cameroon)

Abstract

One of the major challenges of aquatic ecology is to understand how anthropization affects biodiversity and what the consequences on the functioning of hydrosystems. Physicochemical and zoolanktonic variables studied in two ponds (Mokolo and Mopa) in the city of Bertoua, with two sampling stations (surface and depth) per pond and data collected monthly from March 2016 to April 2017 (14 months) allowed us to appreciate the spatial and seasonal dynamics of zooplankton in relation to anthropogenic disturbances. Abiotic variables of the ponds show that they are highly anthropized with relatively high temperatures (> 23 °C), low water transparency (< 70 cm) despite the shallow depth of the ponds (< 170 cm), average oxygenation (> 50%) with hypoxia (< 35%) recorded in the rainy season, high mineralization of the waters, high levels of nutrients, organic matter and photosynthetic pigments (> 30 µg/L). These characteristics allow to classify these water bodies in the category of hypereutrophic ponds. Biological data show fairly diverse ponds with 63 species identified in Mokolo Pond representing 17.89% of the total abundance. In Mopa Pond, 75 species were identified representing 21.30% of the total abundance. This study allowed us to deduce that the structure and dynamics of microcrustaceans communities are under the control of different processes that interact simultaneously. It is mainly influenced by the season, predation and by the depth of sampling, the month and the station having no influence on this distribution.