Marine biofouling is a worldwide problem which costs billions of pounds each year in purchasing and applying the antifouling products in order to clean the fouled surfaces and to repair the damages caused by fouling organisms. Recent immersion panel trials and examination of the fouling literature have revealed the marine green macroalga Ulothrix flacca to be a major pioneering fouling organism on toxic surfaces. Despite its importance, virtually nothing is known about this alga in a fouling context. The present study addressed this issue and attempted to provide a better understanding of its biology, its fouling role and aspects of its resistance to current antifouling biocides and heavy metals. The results of these studies on U.flacca could lead to further research in order to find alternative antifouling products with a lower environmental cost.