Zooplankton structure and biodiversity in the Ghrib dam lake ( w. Ain Defla) .

Abstract

The structure and functioning of aquatic fauna; Zooplankton from the Ghrib dam lake was studied. This study aims primarily to determine the quality of the lake water, through its physicochemical and biological composition, and to know the composition and structure of zooplankton in the Ghrib dam lake in space and time with changes in environmental conditions. For this, we carried out monthly samples during the year 2016 at six stations in the lake. So the spatiotemporal results of the physicochemical parameters revealed changes in the quality of the lake water from one season to the next. The dissolved oxygen content in the water in our study environments is closely linked to the thermal regime of the lake. Temperature influences both the solubility of oxygen in water and the biological activity (photosynthesis and respiration), thus influencing the short-term oxygen concentration balance. the oxygen deficit in the summer season is due to an increase in salinity values. It is also possible that the relationship between the amplitude of variations of oxygen and nitrate is an indirect relationship and that the direct relationship would be with phosphorus. According to the surface water quality grid (SEQ-Water), we classified the waters of Lake Ghrib from average to very good. The results of the taxonomic structure of the zooplankton population allowed us to count 26 apartment taxa in 3 groups, the most important of which is the rotifers with a high abundance of rotifers particularly K. quadrata. The zooplanktonic stand structure depends on many physicochemical factors in Lake Ghrib, and undergoes several changes during the study period. The results reported in this study indicate that the parameter changes resulted in marked seasonal changes in the composition of the rotifer community.