## 3 Results and Discussion
### Environmental Relevance  
No information regarding the presence or levels of DCOIT throughout tropical and subtropical zones has been reported in literature. However, DCOIT has been detected in coastal waters of the temperate climate zone in the northern hemisphere, such as Greece [13], Japan [37] or Sweden [38], reaching a maximum of 3.7 \(\upmu\)g L\({}^{-1}\) reported in a Spanish marina [39]. Since this level is above the LOEC value determined for the DCOIT exposure in the fertilization bioassay and above both LOEC values determined in the embryotoxicity test with DCOIT and SiNC-DCOIT, adverse effects on the reproduction of bivalves may occur. In the other hand, the statistical predicted no effect concentration (PNEC) based on L/E/IC 50 values of DCOIT was recently set on 0.2 \(\upmu\)g L\({}^{-1}\)[40], one order of magnitude higher comparatively to the EC\({}_{50}\) of DCOIT on _P. perna_ fertilization. Thus, environmental concentrations of DCOIT may critically impair natural populations of this species, indicating potential ecological risks worldwide. [PERSON] et al. also shown that the viability of haemocytes of mussels of _P. perna_ are affected by DCOIT exposure as early as 24 h of exposure [41]. It is important to emphasize that the lowest exposure concentration of DCOIT (with environmental relevance) of the present study also caused a reduction on the air survival capacity of _P. perna_ mussels by 45%. Since the natural populations of _P. perna_ mussels inhabits intertidal rocky shores, a continuous exposure, particularly close to marinas or harbors, may cause incapacity of mussels to properly cope with the presence of DCOIT. Thus, a hypothetical decline of the established populations caused by the continuous exposure  
Figure 4: Results of the juvenile mussel survival-in-air after exposition to DCOIT, SiNC-DCOIT and SiNC. Concentration is expressed as DCOIT content (\(\upmu\)g DCOIT L\({}^{-1}\)) in the case of SiNC-DCOIT. Asterisks (*) indicate significant differences relative to the control (\(p<0.05\)). Data are presented as average \(\pm\) standard deviation (SD).  
to DCOIT can have a negative socioeconomic impact in mid and low-income countries. In Brazil, for instance, _P. perna_ mussels has both ecological and economical relevance [42], and many natural populations and mussel farms are located close to marinas, being under potential influence of AF compounds, including DCOIT.  
In this sense, deleterious levels of DCOIT can foster technological developments to control the biocidal leaching from maritime coatings with environmental and economic benefits for the maritime industry. Recently, [PERSON] et al. [40] demonstrated that the encapsulation of DCOIT was able to promote a 25-fold decrease on the marine hazard of DCOIT in temperate ecosystems shown by the increase of the PNEC values from 0.2 to 5 \(\upmu\)g L\({}^{-1}\) on the conventional DCOIT and SiNC-DCOIT, respectively [40]. In the same direction, the present study demonstrated for the first time the promising antifouling efficacy of the novel nanostructured biocide in early life stages of the mussel _P. perna_ together with the reduced toxicity on non-target stages of this neotropical species compared with the conventional DCOIT. These results are explained by the slow and controlled release of biocide in time, as recently demonstrated by [PERSON] et al. [12] in artificial saltwater. Since this is the first ecotoxicological study ever conducted in a tropical species, future research should focus on the holistic assessment of the fate, behavior, toxicity and hazard on the tropical environment of this novel nanoadditive for maritime coatings to avoid the same mistakes of the past when conventional biocides entered in the market without an appropriate assessment of their effects on the environment.