How changes in water quality under the influence of land-based trout farms shape chemism of the recipient streams-case study from Serbia

Abstract

A total of eight trout farms with different production capacities located in highland regions of Serbia were selected for testing of their influence on water parameters of the recipient streams at 46 sites seven times in the course of a year. All of the trout farms can be divided into two groups with respect to the relationship of the values of the parameters recorded at their outlets and downstream sites and those recorded at the control sites. The study showed that trout farms most often cause a statistically significant increase in the contribution of fine particulate organic matter (FPOM %), in the concentrations of NH3, NH4+, and PO43- and in the values of total phosphorous (P-t) and water temperature (t(w)). On the other hand, they cause a statistically significant decrease in the values of dissolved oxygen. In our study, the parameter defined as the ratio of the annual production of a trout farm to the minimal water discharge (Pr/Q(min)) showed a high degree of correlation with the majority of analysed parameters, proven to be a good predictive model for testing the farm's influence on the recipient stream.