Dinâmica de variáveis limnológicas em reservatório durante período de estiagem prolongada, semiárido brasileiro

Abstract

In semi-arid regions, biological, physical and chemical characteristics of artificial reservoirs can be influenced by fluctuations in the water level, which are associated with climatic factors and the demand for water by the human population. Based on the foregoing the present study aimed to analyze the dynamics of limnological variables and the water quality of the Boqueirão reservoirs during prolonged dry season. Therefore, are used data from Aquatic Ecology Laboratory databases of the State University of Paraiba, period November/2005 to December/2012 and conducted monthly collections between October/2014 and September/2015 at a point near the bus, being measured physical parameters (water clarity, pH, temperature, turbidity, electrical conductivity, total dissolved solids and water volume of the reservoir), chemical (dissolved oxygen, total phosphorus, soluble reactive phosphorus, nitrate, nitrite, N-ammoniacal and total nitrogen) and biological (chlorophyll -a). During the dry season the reservoir had water with temperatures ranging between 23.06 and 26.70 ° C, pH ranging from slightly acid to alkaline, high conductivity and total dissolved solids concentrations, soluble reactive phosphorus and N-ammoniacal. Positive and significant correlations were observed between total nitrogen, water temperature and the volume of the reservoir. Negative and significant correlations were observed between the reservoir volume and pH, electrical conductivity, total dissolved solids, turbidity, total phosphorus, soluble reactive phosphorus and n-ammoniac. It was found that the reduction of the tank volume, favored the concentration of nutrients and therefore the growth of algal biomass with the beginning of the dry period. There was also a significant reduction in water transparency, which interfered in the dynamics of phytoplankton in the last months of the dry season.