Ecotoxicological study of the antifouling biocide DCOIT (SEA-NINE™) in Neotropical marine invertebrates

Author(s)

Bruno Galvão de Campos

• Document type: Doctoral Thesis
• Press: São Vicente. 2022-04-03.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. São Vicente
• Defense date: 2022-03-11
• Advisor: Denis Moledo de Souza Abessa

Abstract

After the ban on the tributyltin-based antifouling paints, DCOIT (4,5-Dichloro-2- octylisothiazol-3(2H)-one) has become one of the most used antifouling biocide. Besides being considered a pseudo persistent contaminant in areas with Hight traffic of vessels and toxic to non-target species, the bioaccumulation and trophic transfer of DCOIT in marine organisms remains unknown. The present study is divided into three chapters which: I) presented, as a critical review, a comprehensive compilation of toxicological and environmental data of the more commons biocides, and further used such information in an ecological risk assessment (ERA) of the 11 EU approved antifouling biocides (PT21), which indicated that DCOIT, diuron, dichlofluanid, chlorothalonil, CuSCN, Cu2O, medetomidine, and zineb pose risk for the coastal ecosystems. II) evaluated the degradation of DCOIT, Irgarol, Diuron, and Dichlofluanid during a sediment spiking equilibrium phase of 24 hours in three different time points and concentrations through kinetic degradation models, resulting in the following half-lives: DCOIT and Diuron: < 5 h; dichlofluanid < 2 h; and Irgarol < 6h. The results also indicated that apart from dichlofluanid, the antifouling biocides have shown that in 6 hours of equilibrium the rate of degradation is reduced dramatically. III) Investigated the sublethal effects (biochemical, cellular, and histopathological) of environmentally relevant concentrations of DCOIT on the neotropical oyster Crassostrea brasiliana exposed to increasing concentrations of DCOIT. This study showed that DCOIT causes negative effects on C. brasiliana at all analyzed levels of biological organization. IV) Evaluated the water and whole sediment toxicity of DCOIT in the following species: Perna perna (bivalve), Echinometra lucunter (sea-urchin) Artemia sp (crustacean), Nitrocra sp (copepod) and Tiburonella viscanna (amphipod). The toxicity data were used to calculate endpoints of environmental hazard and risk which were compared to values obtained for temperate species, revealing that tropical pelagic organisms were in avarage 1.7-fold more sensitive to DCOIT compared to non-tropical species. For sediment, based on the environmental concentrations and toxic thresholds, DCOIT possibly presents environmental risk in Korea, Japan, Spain, Malaysia, Indonesia, Vietnam, and Brazil. V) Investigated the bioaccumulation, biomagnification, and trophic transfer of DCOIT and SiNC-DCOIT (a nanoengineered and environmentally friendly alternative of DCOIT) from the marine microalgae Tetraselmis chuii to the mussel Mytilus galloprovincialis during uptake of 24h and depuration of 72h, which showed that the mussels rapidly internalized and metabolized both DCOIT and SiNC-DCOIT, being considered non-bioaccumulative. Yet, food exposure treatment indicated that DCOIT and SiNC-DCOIT can transfer up a food chain with biomagnification capabilities. VI) assessed short and long-term sub-lethal effects of nanostructured and soluble forms of AF biocides (DCOIT; Ag; SiNC-DCOIT; SiNC-DCOIT Ag) and the “empty” nanocapsule (SiNC) on juveniles of Crassostrea gigas after 96 h and 14 days of exposure, indicating that the SiNC-DCOIT presented a lower toxicity profile compared to the free biocide. Overall our results generated important ecotoxicological data for regulatory context that will enable more accurate predictions of risk to the marine environment. The results also indicated that coastal areas close to ports and marinas are hotspots of antifouling contamination being considered the most threatened locations, thus requiring rigorous control of the release rates and strict regulation on these areas (AU)

• FAPESP's process: 17/10211-0 - Ecotoxicological study of the anti-fouling biocide Sea-Nine in neotropical marine invertebrates.
• Grantee: Bruno Galvão de Campos
• Support Opportunities: Scholarships in Brazil - Doctorate