اثرات سرب و كادميم بر تراكم و رشد ويژه جمعيت آنتنمنشعب آب شيرين Daphnia magna

Effects of lead and cadmium on population density and specific growth rate of fresh water cladoceran Daphnia magna

در اين مطالعه تاثير چهار غلظت فلز سرب (صفر، 15، 6/48 و 150 ميكروگرم بر ليتر) و چهار غلظت فلز كادميم (صفر، 1/2، 3/7 و 6/2 ميكروگرم بر ليتر) و با غلظت هاي جلبكي كم (105×2 سلول در هر ميلي ليتر)و زياد (105×6 سلول در هر ميلي ليتر) از Scenedesmus quadricauda بر ميزان تراكم، رشد ويژه و زمان دو برابر شدن جمعيت آنتن منشعب آب شيرين Daphnia magna در شرايط آزمايشگاهي بررسي شد. آزمايش در قالب يك طرح كاملا تصادفي به مدت 21 روز انجام گرديد. نتايج نشان داد كه افزايش فلز سرب و كادميم باعث كاهش معني داري در تراكم و رشد ويژه جمعيت D. magnaمي شود (0/05.

In this study, the effects of four different concentrations of lead (0, 15, 48.6 and 150 μg/L) and four different concentrations of cadmium (0, 1.2, 3.7 and 6.2 μg/L) with low (2×105 cell/ml) and high (6×105 cell/ml) algal concentrations of Scenedesmus quadricauda on the density, specific growth rate (SGR) and doubling time (Dt) of fresh water cladoceran Daphnia magna were investigated. The experiment was carried out as a completly random design for 21 days with three replications. Results showed that the density and SGR were increased when concentrations of lead and cadmium decrease significantly (p<0.05). For lead and cadmium the maximum population density (144 ind./250 ml), maximum SGR (0.16 /day) and minimum Dt (4.3 days) were obtained at 0 concentration of lead and cadmium in high algal density (6×105 cell/ml). In overall, the increasing lead and cadmium concentrations was decreasing of population density and specific growth rate in D. magna.