Assessment of chlorophyll-a, chlorophyll-b and growth rate in freshwater green algae Pseudokirchneriella subcapitata exposed to cadmium and copper

Abstract

In this work, the effect on green algae Pseudokirchneriella subcapitata exposed to different concentrations of cadmium and copper was evaluated through growth rate and the chlorophyll-a, chlorophyll-b concentrations. The algae were exposed for 7 days to five different cadmium and copper concentration ranging from 1 to 1000 μg/l. Data show that cadmium was more toxic to Pseudokirchneriella subcapitata growth than copper, all treatments of cadmium inhibited Pseudokirchneriella subcapitata growth unlike copper, of which only the highest concentration tested (1000 and 100 μg Cu/l) inhibited the growth of algae cells. Regression analysis revealed that growth rate of Pseudokirchneriella subcapitata significantly decreased with increasing concentration of metals ions (Cd – R2=0.7, p < 0.001; Cu – R2=0.99, p < 0.001. Cadmium and copper had the significant adverse effect on the chlorophyll-a and chlorophyll-b concentrations of P.subcapitata cells (chlorophyll-a ANOVA, Cd: F= 10.8, p < 0.001; Cu: F=8.1 p < 0.001, chlorophyll-b ANOVA, Cd: F= 10.16, p < 0.001; Cu: F=10.06, p < 0.001). The results showed that chlorophyll-a and chlorophyll-b concentration were less sensitive to metals than the growth rate.