Abstract:
Moina macrocopa were exposed to different concentrations of unionized ammonia at
pH 7.0±0.43 and temperature of 25.3±0.38 °C in this study. Results show that mortality
increased with increasing unionized ammonia concentration. Complete mortality was
recorded at 3.6 X 10·1 mg NH3 L- 1
• The 24-hour LC50 and 48-hour LC50 values were
0.077 and 0.070 mg NH3 L- 1 respectively. As for chronic test, four concentrations were
experimented; control, environmental concentration (6.92 X 10-4 mg NH3 L-
1
), nonobserved
effective concentration (2.09 X 10·3 mg NH3 L- 1
) and 48-hour LC 10 (1.18 X
10·2 mg NH3 L- 1
). Average longevity, lethal time that causes 50% mortality (LT50), net
reproductive (Ro) and intrinsic rate of population increase (r) were reduced with the
increased concentration of test solutions. Mean generation time (T) at 6.92 X 10-4 mg
NH3 L-
1
was higher compared to control treatment and the value gradually decreased
with higher concentrations. These results suggest that toxicity of unionized ammonia
will cause negative impact to the present population of Moina macrocopa
