Interrelationships among Water Quality Parameters in Recirculating Aquaculture System

Abstract

The study was conducted to investigate the relationships among important water quality parameters in Recirculating Aquaculture Systems (RAS) and hence predicts equation for determining some of the parameters in RAS. Wastewater was obtained from integrated pond of the University of Ibadan Fish farm and passed through bio-filtration treatment at different drying times: 24, 72 and 144hours. The filtrates that were analyzed for using standard procedure included Temperature, pH, Dissolved oxygen, Total ammonia-nitrogen, Nitrite-nitrogen and Nitrate-nitrogen. Statistical analysis (Correlation and Regression) was used to determine the relationships among the water quality parameters and predict equation. Some of the water quality parameters were significantly interdependent. Temperature had significant relationship with all the dependent parameters but with low co-efficient of determination except with DO where the co-efficient of determination is high (R2=0.502) and prediction equation D.O=26.469-0.784T. Temperature and pH used together had significant relationship with strong coefficient determination (0.514 and 0.405) in relation to DO and Nitrite-nitrogen respectively with prediction equations D.O=20.547-0.787T+0.821pH and NO2-N=0.478+0.035T-0.188pH. Though temperature is a good predictor of other water quality parameters, it is encouraged to use Temperature and pH for a more reliable prediction.