Effect of Ionic Copper Toxicity on the Growth of Green Alga, Selenastrum capricornutum

The growth of Selenastrum capricornutum in culture was investigated as a function of ionic copper concentrations to verify the toxicity and physiological variation. In a <TEX>$Cu^{++}$</TEX> excess culture (E: <TEX>$Cu^{++}$</TEX> of <TEX>$130{mu}g/l$</TEX>), the growth rate (K)(0.32) was lower than that of the control culture (C: <TEX>$Cu^{++}$</TEX> of <TEX>$0.065{mu}g/l$</TEX>) (0.61) after 8 days and the exponential growth rate (<TEX>$R_E$</TEX>) was also found to be lower in culture E (1.1) than culture C (2.9). On the contrary, the K of S. capricornutum in trace <TEX>$Cu^{++}$</TEX> culture (<TEX>$T_1$</TEX> and <TEX>$T_2$</TEX>, 0.72) after 6 days tended to be more increased than culture C (0.68). From 8 to 14 days of culture, the amounts of chlorophyllls a and b were increased in culture C (chlorophyll a, <TEX>$106->126{mu}g/g$</TEX> dry wt; chlorophyll b, <TEX>$158->208{mu}g/g$</TEX> dry wt; chlorophyll b were decreased in culture E (chlorophyll a, <TEX>$309->235{mu}g/g$</TEX> dry wt; chlorophyll b, <TEX>$405->352{mu}g/g$</TEX> dry wt). The amounts of chlorophylls in ionic copper trace culture (<TEX>$T_1$</TEX> and <TEX>$T_2$</TEX>) [(chl a/b) of <TEX>$T_1$</TEX>: <TEX>$384/620;{mu}g/g$</TEX> dry wt; (chl a/b) of <TEX>$T^2$</TEX>:<TEX>$320/467{mu}g/g$</TEX> dry wt] were increased more than the culture C(<TEX>$260/387{mu}g/g$</TEX> dry wt). Howeveer, when photosynthetic rates were normalized to the dry weight of algae, the control culture continued to showed higher values than the treated culture (<TEX>$T_1$</TEX>). An appropriate amount of ionic copper (<TEX>$T_1:;26;{mu}g/l$</TEX>) stimulated the grwoth of S. capricornutum than the ionic copper content of <TEX>$13;{mu}g/l$</TEX> (<TEX>$T_2$</TEX>), while the excess amount of ionic copper (<TEX>$130;{mu}g/l$</TEX>) resulted in the highest toxicity to the growth of S. capricornutum.