This study assessed the effects of physical and chemical stresses on marine algae cells Tetraselmis suecica and its implications on ultrafiltration (UF) performance. It was found that physical stress did not have significant effect on membrane fouling performance. Chemical stress by chlorination significantly lysed algae cells and reduced membrane fouling. Physical and chemical stresses increased the low molecular weight organics fractions which have no obvious effect on UF membrane fouling due to its low membrane rejection. However, this reduced the reverse osmosis feed quality significantly. Results indicate the importance of appropriate management of physical and chemical stress parameters in desalination plants.