Calibration of physicochemical parameters in aquaculture. A case study of tilapia breeding in Mozambique

Abstract

This paper discusses the adequacy of methods used in monitoring the aquatic environment in aquaculture. It is assumed that the strategy of controlling each of the environmental parameters by observing their compliance with the technical limits established in aquaculture is not sufficient to highlight all the aspects that may compromise the quality of the process. Therefore, the univariate methods that are usually used in water monitoring in aquaculture cannot show aspects of the process derived from the joint variability between the parameters. Thus, a multivariate method for monitoring the aquatic environment in aquaculture based on Hotelling’s T2 chart was proposed in this paper. Data on four physicochemical parameters (oxygen, temperature, pH and transparency) were collected from four aquatic species breeding ponds at the company Aquapesca in Mozambique, located in southeastern Africa. The correlation structure evidenced in the four physicochemical parameters analyzed showed a strong and positive relationship between temperature and pH, oxygen and transparency are inversely correlated. This correlation structure indicates that a possible reduction in water temperature also reduces the pH and vice versa, while a reduction in transparency implies an increase in dissolved oxygen. The multivariate method used shows the relationship between the parameters and the strategies to manage them, as well as the control strategy of the multivariate structure through Hotelling’s T2 chart, pointing out and correcting all the aspects that may compromise the quality of the breeding of the species in aquaculture.