Relationships between climatic and abiotic parameters and the reproductive period of Macrobrachium birai LOBÃO, MELO &FERNANDES and M. petronioi MELO, LOBÃO & FERNANDES [DECAPODA, PALAEMONIDAE] of Branco River [CANANÉIA í SP í BRAZIL])

Abstract

In order to determine relationships between the reproductive cycles of Macrobrachium birai and M. petronioi population and the climatic periodism of the region and the behaviour of some limnological characteristics of the water of Branco River (Itapitangui - Cananéia - SP), 24°54'44"S and 47°58'30"W, biological aspects of the two species and physical and chemical data of the water were recorded during the period of October/1985 to March/1988 , through monthly samplings. The median values of the limnological characteristics were as follows: water temperature 22.0°C; water layer 57.7 cm; pH 6.8; color 50 mg/L; turbidity 4.9 FTU; conductivity 75 µS/cm; alcalinity 24.23 mg/L CaC0₃; ammonium 0.20 mg/L; nitrite 0.6 µg/L; nitrate 0.09 mg/L; phosphate 30 µg/L; silic 6.48 mg/L; total hardness 20.83 mg/L CaC0₃; calcium 3.37 mg/L; magnesium 3.0 mg/L; iron 0.48 mg/L; chloride 9.53 mg/L; dissolved oxygen 8.06 mg/L O₂; oxygen saturation 96%; oxidability 3.13 mg/L; bicarbonate 29.58 mg/L; total carbon dioxide 29.02 mg/L and free carbon dioxide 7.73 mg/L. It was also observed that M. birai presents nocturnal rhythm and reproduces during the summer when the values of some characteristics of water such as conductivity, alcalinity, total hardness and bicarbonate tend to diminish, and that M. petronioi has diurnal rhythm and reproduces in spring when the above parameters tend to have their values increased.