EVALUATION OF IMPACT ON WATER QUALITY DUE TO THE SEMI INTENSIVE PRODUCTION OF TROUT (Oncorhynchus mykiss) IN FLOATING CAGES IN THE ARAPA LAKE - PUNO

Abstract

This research was developed in the Arapa lake, located in Puno, physicochemical parameters and a simplified mathematical model for the phosphorus were evaluated. Experimental design "BACI" (Before-After-Control-Impact) was used to assess the impact on water quality. During the "After-Impact" period, 70000 trouts were farmed every 3 months; then the food consumed and increased biomass was registered for each batch of trout farmed. In this period significant difference in acidity, carbon dioxide, phosphates and electrical conductivity was expressed.

Total suspended solids showed a decrease. Alkalinity, pH and dissolved oxygen remained constant. Product of the digestion of food 611 kg of phosphorus were discharged into the Arapa lake; then the simplified mathematical model was established to determine the evolution of dissolved phosphorus versus time. From de 611 kg of phosphorus discharged into the Arapa lake, 246 kg were directed to accumulate in sediment and 365 kg were dissolving in the entire volume of water. The concentration of phosphorus in the Arapa lake increased with trout farming activity, reaching values of 32.79 mg/m3 of PO4-P to classify it as eutrophic lake as rated by Vollenweider