Zooplankton community structure of Lake Edku, Egypt

Abstract

This research was designed to assess the impact of water quality on zooplankton community structure of Edku Wetland, Egypt. Zooplankton and water samples were collected seasonally from January to November 2004. Seven sampling stations were selected to represent different habitats of the Lake that were classified in this study to three distinct habitats; Body of the lake (BL), Drainage (D) and Lake-Sea Connection (LSC). Several physical and chemical parameters were studied, such as temperature, transparency, alkalinity, water pH, chlorosity, electrical conductivity, water depth, dissolved oxygen (DO), chemical oxygen demand (COD), biological oxygen demand (BOD) and water hardness. Zooplankton community is composed of 72 species dominated by three groups; Rotifera, Copepoda and Cladocera. These groups were representing 89.5%, 6.8% and 2.3% of total zooplankton density, respectively. The index of species abundance (ISA) and modified index of species abundance (MISA) showed that the small sized animals, such as Rotifera became the most dominant especially, genus Brachionus, which is considered as an indicator for organic pollution and eutrophication. Community ordination, trellis diagram and other biostatistical and multivariate analyses techniques showed that within the lake, similar ecological habitats have similar community structures for zooplankton and differ among different habitats. Comparing the present results with previous data of other researchers showed that zooplankton community shifted from dominance of Cladocera and large zooplankton species to rotifers and small zooplankton by increasing eutrophication.