Physiological and biochemical responses of the marine dinoflagellate Prorocentrum minimum exposed to the oxidizing biocide chlorine

다국어 초록 (Multilingual Abstract)

Toxic effects of the commonly used biocide chlorine (Cl<SUB>2</SUB>) on the marine dinoflagellate Prorocentrum minimum were assessed using growth-, pigment- and enzyme activity-based endpoints. Cell count, chlorophyll a levels, carotenoids, and chlorophyll autofluorescence were monitored up to 72h after exposure to Cl<SUB>2</SUB>, and these parameters showed a dose- and time-dependent decrease. The 72-h median effective concentration (EC<SUB>50</SUB>) based on growth rate was 1.177mgL<SUP>-1</SUP>. Cl<SUB>2</SUB> dose above 0.5mgL<SUP>-1</SUP> were toxic to P. minimum after 6-h exposure to Cl<SUB>2</SUB>; the effect increased with increase in exposure time as revealed by a significant reduction in growth rate and decreased chlorophyll fluorescence. Moreover, the activities of antioxidant enzymes, including superoxide dismutase and catalase, were altered proportionally with increasing Cl<SUB>2</SUB> dose. The results of this study show that Cl<SUB>2</SUB> concentrations as observed in power-plant discharges and in drinking-water systems cause physiological and biochemical damage to the microalgae.