Comparison of the metabolism of two floodplain lakes of the Trombetas River (Pará, Brazil) based on a study of diel variation

The diel variation of temperature, pH, electrical conductivity, dissolved oxygen concentration and chlorophyll-a was investigated in Batata and Mussurá Lakes on the Trombetas River floodplain. The diel variation of temperature was distinct in both lakes. The water column of Batata lake was completely mixed after 22ºº hour and Mussurá lake developed a well stablished gradient of temperature (differences up to 5.6 °C between surface and depth) which persisted all over the period studied. The thermal behavior determined the diet variation of the other parameters studied, which presented a homogenous vertical distribution in Batata Lake and remained stratified in Mussurá Lake. Chlorophyll-a concentrations were considerably lower in Batata Lake (1.8 µg/l) than in Mussurá Lake (10.8 µg/l) and resulted in production values (measured by oxygen diel variation) of ca. 2.6 g O2*m⁻²*d⁻¹ the first and 18.2 g O2*m⁻²*d⁻¹ in the former one