Preliminary evaluation of the toxic effects of the antifouling biocide Sea-Nine 211 in the soft coral Sarcophyton cf. glaucum (Octocorallia, Alcyonacea) based on PAM fluorometry and biomarkers

Sea-Nine 211 is a new biocide specifically formulated for antifouling paints and being considered to have a low environmental impact. Even with a short environmental half-life, this compound can cause toxic effects on marine organisms. This study used PAM fluorometry and biomarkers of oxidative stress (GST, CAT and LPO) to monitor potential toxic effects of Sea-Nine 211 on fragments of the soft coral Sarcophyton cf. glaucum. After exposure to concentrations of 1-100 μg/l for 72 h, CAT activity was inhibited under the two highest concentrations, being in accordance with the activity of GST. LPO activity (as TBARS) and photosynthetic efficiency of endosymbiotic zooxanthellae were not significantly affected. These results show that PAM fluorometry alone cannot detect the full effects of Sea-Nine 211 on Sarcophyton cf. glaucum and should be used together with other biomarkers. This holobiont driven approach to evaluate chemical toxicity in photosynthetic corals is therefore recommended for biocides which are not photosystem II inhibitors