Movimentos de massas d’água através de derivadores lagrangianos e implicações para o entendimento de processos ecológicos

Abstract

Physical, chemical and biological processes that occur in aquatic ecosystems are strongly dependent of hydrodynamic. Process responsible for horizontal and vertical dispersion are important points for the comprehension of nutrient cycle, substances dispersion, primary productivity and others ecological process. In despite of many studies have been done in others country, few studies were made in continental Brazilian aquatic ecosystems. During many years, lagrangian drifters have been used in oceanography to understand ocean water current. The purpose of this work was: (1) development of the lagrangian drifters adapted to continental ecosystems; (2) development of termistor chain to understand the vertical thermal structure; (3) use of drifters to understand biochemical process and; (4) understand the density currents and the influence of the dam to the water circulation in the reservoir. Experiments were carried out in APM Manso reservoir, located near Cuiaba city, Mato Grosso. Our studies showed: (1) most of movements in the surface layer were wind induced; (2) current was influenced by turbines suction (direct influence) and by return current from the dam (indirect influence); (3) advective ovements were predominant in intermediary region of the reservoir. It indicates that small temporal variation in the initial condition could be as important as small spatial variation; (4) the interaction among river and reservoir water engendered the Kelvin-Helmholtz instability. It causes vertical mixing of deep water that can increase phytoplankton density.