Spatio-temporal distribution and composition of zooplankton in Wadi Hanifah stream Riyadh (Saudi Arabia) and Abu Zabaal lakes (Egypt)

Information of biological communities is important to assess the qualities of aquatic systems receiving wastewater. Zooplankton communities have a cosmopolitan distribution, short life cycle and high sensitivity to pollutants, which make them useful as biological indicators of the aquatic environment. In this study, the physicochemical variables and zooplankton community structure of two different aquatic habitats receiving municipal sewage in Egypt and Saudi Arabia were investigated. Average electrical conductivity was recorded as 8346 and 4398 muS/cm, respectively from Abu Zabaal lakes (AZ lakes) and Wadi Hanifah (WH streams). The highest concentration of total ammonia, nitrite, nitrate and orthophosphate were recorded in WH. A total of 43 and 19 taxa and species of zooplankton were recorded in AZ lakes and WH streams, respectively. The standing crops of total zooplankton were much higher in WH streams (av. 5325 Ind. L-1) as compared with AZ lakes (av. 5325 Ind. L-1). Rotifers dominated amongst the zooplankton in AZ lakes with a contribution of 67.2%, while protozoa was the abundant group at WH streams and contributed 78.9% of the total zooplankton density. Brachionus plicatilis and Synchaeta oblongs were the most abundant rotifer species at lakes, while Brachionus calyciflorus, Keratella cochlearis and Testudinella patina were abundant at streams. It is concluded that low/reduced in zooplankton diversity at Wadi Hanifah streams may be induced by sewage and others domestic pollutant discharged in it.