A comparison of the biofouling potential of field-collected and laboratory-cultured <i>Ulva</i>

The marine algae <i>Ulva</i> spp. are commonly used as model biofouling organisms. As biofouling studies are primarily conducted using field-collected specimens, factors including species identity, seasonal availability, and physiological status can hinder the replicability of the results. To address these limitations, a protocol was developed for the on-demand laboratory culture and release of <i>Ulva</i> zoospores. The biofouling potential of laboratory-cultured and field-collected <i>Ulva</i> blades was compared using a waterjet. No significant differences were found between field and laboratory-cultured samples in either spore adhesion (before waterjet) or the proportion of spores retained after waterjet exposure. However, there was significant variability within each session type in pre- and post-waterjet exposures, indicating that spore adhesion and retention levels vary significantly among trial runs. In addition, all our laboratory cultures were <i>Ulva</i> Clade C (LPP complex). In contrast, our field samples contained a mix of <i>Ulva</i> Clade C, <i>U. compressa</i> clade I, and <i>U. flexuosa</i> Clade D. This protocol for on-demand production of <i>Ulva</i> spores can improve biofouling research approaches, enables comparison of results across laboratories and regions, and accelerate the development of anti-biofouling strategies.