Limnology of a coastal clear-water stream of the Atlantic Rain Forest, Southeast Brazil
Da Silva Vieira, Martiniana; Eichbaum Esteves, Katharina
published: May 29, 2002
ArtNo. ESP141015402005, Price: 29.00 €
Water temperature, pH, conductivity, color, total suspended solids, total pigments, turbidity, NO2-N, NO3-N, PO43-NH4N, dissolved oxygen, consumed oxygen, alkalinity, total hardness, SiO2, total Fe, Ca2+, Mg2+, Na+, K+, Cl- were determined monthly from January/1995 to May/1996 in the Pedra Branca river, at five different altitudes (120 m, 80 m, 50 m, 30 m, 15 m). Land use and geomorphology were analyzed in each subcatchment using aerial photographs. Results showed that this river is oligotrophic, since most nutrients occurred in very low concentrations. The cationic order of dominance was Na+ >K+ >Mg2+ >Ca2+ and the anionic Cl- >HCO3-; salinity varied between 0.37-0.39 meq/L. An Analysis of Variance with Repeated Measures applied to the data showed that Ca2+, alkalinity, color, turbidity and nutrients did not show significant effects of altitude and season (P<0.05), while total fe, conductivity, ph, sio2 and TSS only showed effects of altitude. Total hardness and Mg2+ showed significant effects of altitude and season with interaction (P<0.05). it was concluded that some physical and chemical variables of pedra branca river such as dissolved oxygen, k+, Na+ consumed oxygen, total pigments and water temperature are strongly influenced by physiographical features such as altitude and climate. Maps indicated that these conditions probably represent the original state of a clear-water river of the Atlantic rain forest, as only primary forest was observed without any anthropogenic influences.