Structural and Functional Changes in River Microbial Communities After Dairy Wastewater Discharge

ABSTRACTThe introduction of an integration approach for management of the water basins, including assessment and control of stream water quality and sediment quality, as well as regulation of the pollutant influx in the water receiver, is necessary. The changes in the microbial communities, as a response to the chronic discharge of untreated dairy wastewater, were followed in river and in depth, in three river components “stream water—sediment water—sediments”. The water quality of Leva River decreased after dairy wastewater discharge as the microbial communities reacted with structural and functional changes, related with enhancement of aerobic heterotrophs and the values of total dehydrogenase activity and phosphatase activity index. The result was a decrease of organic matter and nutrients in the stream water in Station 4. However, an improvement of river water quality was not ascertained according to the Bulgarian State Standard. The applied ecological theory for r/K- strategists showed that in the st...