Effect of sodium dodecyl sulfate and three commercial detergents on the growth and physiological parameters of the filamentous green alga Cladophora sp.

Surfactants are pollutants of environmental concern. Released in large volumes into aquatic environments, they have detrimental effects on the growth and physiological functions of living organisms. This study aimed to determine physiological effects of sodium dodecyl sulfate (SDS) and three commercial detergents on filamentous alga Cladophora sp. It followed the methodological guidelines of the Organisation for Economic Cooperation and Development (OECD) to test seven concentrations of SDS (0, 0.1, 1, 5, 10, 50, and 100 mg/L) and six concentrations of commercial detergents (0, 1, 15, 30, 45, and 60 mg/L) using three replicates in a fully randomized design. At the end of the exposure period, we assessed growth inhibition and physiological functions related to cellular lipoperoxidation—a process where lipids in the cell membrane are damaged by free radicals—and the production of photosynthetic pigments, proteins, carbohydrates, and lipids. The results showed that increasing concentrations of SDS and detergents caused a reduction in both growth and protein content; growth decreased significantly from a concentration of 1 mg/L for all detergents while proteins decreased by up to 82.2% at the highest SDS concentration. In general, the production of pigments (chlorophyll-a, chlorophyll-b, and carotenoids), thiobarbituric acid reactive substances (TBARS), carbohydrates, and lipids increased with rising concentrations of SDS and commercial detergents, with the effect being more significant in some commercial detergents. TBARS increased up to 6-fold at the 100 mg/L concentration. The species showed an imbalance between oxidative and physiological processes, with different responses depending on the type of surfactant. Given that surfactants are common pollutants in the waters of poor and developing countries, these results suggest that understudied species, such as filamentous algae, may be at risk, even at sublethal concentrations due to the physiological stress induced by the pollutant.