Water Quality and Plankton Population Abundance Affected by Earthen Ponds Management

Abstract

The study was conducted in two earthen ponds fish farming systems located at (El-Rayed area- Kafer El-Shiak governmentEgypt); namely, feed and fertilizer fish farming systems. Each system was replicated in four ponds (8000m2 each), to determine water quality, phytoplankton and zooplankton abundance. Nile tilapia (Orechromis niloticus); mullet (Mugil cephalus) and catfish (Clarias garipinus) were cultured in each pond at initial weight of 2, 30 and 50 g, respectively. The present study aimed to evaluate two fish farming systems differing in pond management procedures in the Nile Delta regions. Results apparent insignificant differences between the two fish farming systems in terms of water temperature (ranged 12.7 to 30.9°C from winter to summer months), salinity, EC and total hardness. Whilst, fertilizer fish farm had significantly high levels of pH, DO, secchi disc, total alkalinity, orthophosphate, TAN, NO2, NO3, algal abundance and chlorophyll “a” n water compared to those of feed fish farm. Significant increase (P<0.05) in phytoplankton and zooplankton abundance were observed in fertilizer fish farm compared to feed fish farm, this was due the high organic manure inputs to pond water during all seasons including winter at one ton per feddan every 10 days.