THE INFLUENCE OF FLOATING MEADOWS AND HYDROLOGICAL CYCLE ON THE MAIN ABIOTIC CHARACTERISTICS OF A TROPICAL OXBOW LAKE

Abstract

Temperature, dissolved oxygen, pH, electrical conductivity, and transparency were studied in the littoral and limnetic zones of Lagoa do Infernão, one of the several oxbow lakes of the Rio Mogi-Guaçu (São Paulo, Brazil). The objective of this study was to evaluate the influence of the floating meadows wich occur in the littoral zone, and the hydrological cycle on the principal abiotic characteristics of the water column. The results demonstrated that the aquatic macrophy1e stands directly influence the vertical profiles of temperature and dissolved oxygen in the littoral zone. On the other hand, they do not exert a direct influence on pH values and e1ectrical conductivity of the water. The principal determinant of these characteristics in the system as a whole is variation in water level: during the rainy season, in allocktonous material from floodes areas modified the limnological characteristics.