EFFECTS OF HEAVY METAL ON Tetraselmis chuii

We determined the toxic effects of seven metals. copper (Cu), manganese (Mn). zinc (Zn), cobalt (Co). molybdate (Mo), lead (Pb), and cadmium (Cd) on the microalgae Tefraselmis chuii (Butcher, 1959). We exposed 50 mL of cultivated microalgae (f/2 Gaillard) in the exponential growth phase. with three replicates, to concentrations of 0 (control). 0.1, 1.0, 5.0, 10, 25. and 50 g L of each metal for 72 hours. The cellular count was recorded daily to evaluate any potential lethal effects. An increase in cellular density was seen in the control treatment. All treatments exposed to metals showed a logarithmic increase in cell density within 48 hours, with a cellular decrease that became evident later on. This study result with an insignificant decrease at low concentrations of Cd, Pb, and Cu at 24 hour was probably attributed to their use as micronutrients at these low concentrations. The most lethal effect was observed with Cd treatment, which killed 50% of the microalgae population at a concentration of 0.62 mu g L-1. In this study, this concentration was three times lower than that of lead and mercury. while being ten times lower than that of cobalt and molybdate. To elucidate the adverse effects on seawater environments, the microalgae Tetraselmis chuii is recommended as a model species.