EFFECTS OF LOW WATER PH ON LEAD TOXICITY TO EARLY-LIFE STAGES OF THE COMMON CARP (CYPRINUS-CARPIO)

Carp eggs were exposed immediately after fertilization to Pb concentrations of 0.12 to 0.96 mumol 1(-1) at water pH 7.5 and 5.6. At regular intervals mortality, the incidence of spinal cord deformation, heart rate, body movements, hatching success, and whole body concentration of K, Na, Mg, Ca, and Pb were assessed. At pH 7.5, Pb increased heart rate, and decreased body movements, while at pH 5.6, Pb also reduced hatching success, caused spinal cord deformation, decreased net Ca2+ uptake, and increased mortality of the larvae, in a concentration-dependent manner. In controls of pH 5.6 no significant changes of any of the above parameters were observed when compared to controls at pH 7.5.