Abstract
Chlorination is a widespread fouling control practice in water intake structures of power plants and desalination plants. Chlorine dioxide is used as an alternative to chlorine gas and sodium hypochlorite for controlling biofilms and biofouling. In this study, the physiological responses of two macroalgal species Ulva reticulata and Hypnea musciformis to chlorine dioxide treatment was studied under laboratory conditions. The algal samples were exposed to 0.05, 0.1 and 0.5 mg l(-1) of chlorine dioxide for 5 days. The chlorophyll-a, carotenoid content and total polyphenol levels were analysed. The algal extracts were also analysed using GC-MS to understand the changes in the biochemical profile of the algae after treated with chlorine dioxide. Results indicated an increase in chlorophyll-a, carotenoid and total polyphenol content during initial exposure duration and further treatment showed a decrease in these parameters. The chlorine dioxide treatment also affected the fatty acids composition of the macroalgae. The physiological responses observed in this study indicate that chlorine dioxide as an antifouling biocide has toxic effects on these macroalgae.