Comparative toxicity of alternative antifouling biocides on embryos and larvae of marine invertebrates

This study evaluates the impact of commonly used "booster" biocides (chlorothalonil, Sea-Nine 211, dichlofluanid, tolylfluanid and Irgarol 1051) on early developmental stages of marine invertebrates of commercial and ecological relevance. Toxicity tests were conducted with embryos and larvae of the bivalve Mytilus edulis, the sea-urchin Paracentrotus lividus and the ascidian Ciona intestinalis. Toxicity was quantified in terms of the EC50 (median effective concentration) and EC10 reducing embryogenesis success, larval growth and larval settlement by 50% and 10% respectively. The EC10 and EC50 for chlorothalonil ranged from 2 to 108 and from 25 to 159 nM; for Sea-Nine 211 values were 6-204 and 38-372 nM; for dichlofluanid effective concentrations were 95-830 and 244-4311 nM; tolylfluanid yielded values between 99-631 and 213-2839 nM; and Irgarol 1051 was the least toxic compound showing values from 3145 to >25600 and from 6076 to >25600 nM. Those biocides may be ranked in the following order from highest to lowest toxicity to embryos and larvae of M. edulis, P. lividus and C. intestinalis: chlorothalonil>Sea-Nine 211>dichlofluanid=tolylfluanid>Irgarol 1051. The registered effective concentrations were compared to worst-case environmental concentrations reported in literature in order to evaluate the risk posed by these biocides to those invertebrate species. Our data support that chlorothalonil, Sea-Nine 211 and dichlofluanid predicted levels in marinas represent a threat to M. edulis, P. lividus, and C. intestinalis populations, whilst Irgarol 1051 showed no toxic effects on the biological responses tested here at worst-case environmental concentrations.