Water characterization of Igarapés used in fish farming in Manaus and Iranduba, Amazonas, Brazil

Abstract

The objective was to study the impacts of the implementation of fish farming projects (fish breeding), the quality of water effluents from these enterprises, in upland streams on properties in the municipalities of Manaus and Iranduba. We chose to monitor some physical-chemical attributes such as turbidity, dissolved oxygen, chlorophyll-a, ammonia, nitrite, nitrate and phosphorus because they are able to establish a relationship between fish farming and the loss of environmental quality of water. For this study, 16 sample units were analyzed, with two collection points each, upstream and downstream in the fish farming enterprises in uplands of continuous land (continuous flow), in two different periods in the year 2016 and 2017. The main variables studied in the analysis stage of an aquatic ecosystem, including fishing grounds, they can be: water temperature, pH, turbidity, concentration of nutrients (nitrite, nitrate and ammonia, total phosphorus), dissolved oxygen, chlorophyll. There was no significant difference in temperature, dissolved oxygen, ammonia and nitrate. There was a significant difference for the depth, turbidity and nitrite parameters. There was a significant difference for phosphorus and pH and no difference was observed for chlorophyll-a. The analyzed parameters were sufficient to demonstrate that the fish farming activity in Igarapé alters turbidity, nitrite and phosphorus and pH. Based on these parameters, better control of water quality in fish farming in Igarapé is suggested as water flow and better quality of the feed offered to fish.