The impact of agricultural drains on water quality and Phyto- zooplankton communities in fish farms, Egypt.

This study was carried out on two fish farms in Kafr El-Sheikh and Sharkia governorates during 2011. The water supply sources of these farms were El-Gharbia and El-Wady drains respectively. The mean values of physico-chemical parameters of water in El-khashaa and Abbassa fish farms were: water temperature (24.66 and 24.95 ℃); pH (9.23 and 8.67); transparency (12.12 and 15.24 cm); DO (5.36 and 6.3 mg/l ); total alkalinity (330.9 and 340.3 mg/l) and total hardness (689.5 and 260.0 mg/l), respectively. The major nutrient concentrations (N P) at the main feeder were much higher than the corresponding values at fish farms. Nitrogen concentrations analysis indicated the highest values of NH3-N over NO3-N in the selected fish ponds (1.94 and 1.22 mg/l respectively). Phytoplankton in the present study were represented by four groups; Chlorophyceae, Cyanophyceae, Bacillariophyceae and Euglenophyceae, where Chlorophyceae dominated other groups. Zooplankton were represented by four groups; Rotifera, Copepoda, Ostracoda and Cladocera. Rotifera and Cladocera were the dominant groups. Results indicated that the drainage water affects physical, chemical and biological characteristics of fish farms.