Tolerance and bioremediation potential of the macroalga Caulerpa prolifera to ultraviolet filters pollutants.

Ultraviolet filters (UVFs) as benzophenone-3 (BP-3; oxybenzone) and 4-methyl-benzylidene camphor (4-MBC; enzacamene) have recently been included among the Contaminants of Emerging Concern in marine ecosystems. The aim of this study was to investigate the tolerance and the remediation potential, in presence of BP-3 and 4-MBC, of the macroalga Caulerpa prolifera (Forsskål) Lamouroux, abundant in touristic coastal areas frequently affected by these contaminants. To the purpose, a manipulative aquarium experiment was conducted. Thalli of C. prolifera were exposed to BP-3 and 4-MBC for three weeks and the water concentration of such pollutants was estimated by ultra-performance liquid chromatography coupled with mass spectrometry, considering tanks with and without the macroalga. Moreover, the eventual changes in the algal performance and in its bacterial community composition were determined with and without UVFs. Finally, the enzymatic activity of two common biomarkers of algal stress (glutathione reductase and superoxide dismutase) was evaluated in relation to the treatment. The performance of C. prolifera appeared to be negatively affected by the UVFs, with a relevant reduction in its growth rates and an increase in its enzymatic activity, suggesting a stress condition. Nevertheless, no mortality events were observed. Moreover, a significant reduction in the UVF concentration was recorded in tanks with the alga, where some UVF degrading bacterial taxa were also found. According to these results, C. prolifera seem to play an active role in the absorption of BP-3 and 4-MBC, that in presence of the alga, also seem to undergo a degradation process mediated by its associated bacteria.