Impact of Fish Farm Management on Physico-chemical Properties of Water and Sediments in earthen ponds

Abstract

The study was conducted in two fish farms located at El-Rayed area, Kafer El-Sheikh governorate, Egypt, to assess the impact of management on water and sediments characteristics. The two farms had different feeding regimes; the first farm uses pelleted feed, while the second one receives organic fertilization, was replicated in four ponds (8400m 2 each). Water samples were collected monthly and sediment at the beginning and the end of experimental period to determine both water and sediment quality. The results revealed that there were no differences in water in temperature, electrical conductivity and total hardness between the two farms. While, noted significant differences were observed in water pH, dissolved oxygen (DO), secchi disk, total alkalinity, orthophosphate, nitrogen component (ammonia, nitrate and nitrite) and chlorophyll "a". Concerning physical parameters of sediment, an increase in organic matter content in surface layer was observed compared the subsurface layer especially in fertilizer fish farm. The differences in sediment pH were insignificant. The changes in sand and clay percentage in surface layer were higher than the subsurface layer. Chemical properties of sediment changed in terms of salinity and ions content, leaching from the surface to the subsurface layer. Salinity and different ions were decreased in the surface layer of the two fish farms by the end of the experiment. The surface layer in the fertilizer fish farm contained a higher percentage of nutrients nitrogen, phosphorous and potassium compared the feed fish farm. Water quality in fish farms is greatly influenced by feed management and fertilizer inputs which in turn affect sediment quality in ponds. Key word: Fish farms, water quality, sediment quality, physical-chemical properties. INTRODUCTION Decisions regarding fertilization and supplementary feeding are especially important because they are major determinants of nutrient for fish growth and major causes of water quality problems. Fish ponds have resulted in